Determination of tuberculosis in animals. Tuberculosis of small animals and birds

1.2. TUBERCULOSIS in animals

Tuberculosis(Latin, English - Tuberculosis) - a severe chronic disease of animals of many species and humans, characterized by the formation of various organs specific nodules - tubercles that undergo caseous necrosis and calcification (see color insert).

IsT orical information, distribution, degree of danger T and and damage. Tuberculosis has been known since ancient times. Signs of illness in humans were described by Hippocrates in IV century BC The term “tuberculosis” was first used by the French physician Lenek (1819); the contagiousness of the disease was proven by J. A. Villemin (1865). The causative agent of tuberculosis was discovered by R. Koch (1882), and he was the first to produce (1890) the allergen - tuberculin. In 1924, A. Calmette and S. Guerin produced the BCG vaccine ( BCG - Bacterium Calmette - Guerin , Calmette-Guerin bacterium) for specific prevention tuberculosis in humans.

Animal tuberculosis is common in many regions of the world; only in developed countries in Europe and North America has it been almost eliminated. The danger level of tuberculosis for humans increases: at the end XX - early XXI V. The global epidemic situation regarding tuberculosis has worsened significantly.

The disease causes serious economic damage to livestock production, which is associated with a decrease in productivity, premature culling and slaughter of animals, lengthy and expensive anti-epizootic measures and other costs.

The causative agent of the disease. The causative agent of tuberculosis is Mycobacterium tuberculosis. The Mycobacterium genus includes more than 30 different species of pathogenic and non-pathogenic microorganisms. Tuberculosis is caused by 3 pathogenic types:

1) Mycobacterium tuberculosis (human species) causes disease in humans. Pigs, cats, dogs, cattle, fur-bearing animals are also susceptible to it, but birds (except parrots) are not susceptible;

2) Mycobacterium bovis (bovine species) causes disease in all types of agricultural and wild animals, including fur-bearing animals, as well as humans. Birds are not susceptible;

3) Mycobacterium avium (avian species) causes disease in domestic and wild birds; pigs are also susceptible; Animals of other species and humans are rarely infected.

In terms of morphology and cultural properties, mycobacteria of the listed species are largely similar to each other. These are thin straight, often slightly curved rods 0.8...5.5 µm long, located singly or in groups in smears. Mycobacteria are strict aerobes, nonmotile, do not form spores, acid-alcohol-resistant; are stained bright red by the Ziehl-Neelsen method, while other microflora are blue. They are cultivated on glycerin MPA, MPB, egg and synthetic media. Mycobacteria of the human species grow in 20...30 days, of the bovine species - 20...60 days, of the avian species - 10...20 days. If there is no growth, it is recommended to keep the crops in a thermostat for 3 months. The species of the causative agent of tuberculosis is determined by the characteristics of their growth on artificial nutrient media and the pathogenicity of certain types of the causative agent of tuberculosis for laboratory animals of various species. The main properties of mycobacteria are given in Table 1.2.

1.2. Basic properties of mycobacteria

Legend: “+” - there is growth; “-” - no growth; “±” - some crops grow under these conditions, others do not.

In nature, in addition to tuberculosis, there are opportunistic atypical and saprophytic mycobacteria. Animals infected with them may react to mammalian tuberculin, which causes difficulties in the allergic diagnosis of tuberculosis.

Mycobacteria are very resistant to chemicals and various environmental factors. M. bovis in soil and manure remains viable for up to 4 years, M. avium - up to 10 years or more. In products obtained from sick animals, the tuberculosis pathogen persists: in milk for up to 19 days, in butter for up to 300 days, in cheese for 145...200 days, in frozen meat for up to 1 year, in salted meat for 60 days. In the corpses of cattle and birds, mycobacteria persist from 3...6 to 12 months. According to various authors, in a wet state, Mycobacterium tuberculosis dies at 50°C after 12 hours, at 60°C after 1 hour, at 70°C after 30 minutes, at 90°C after 1 minute, at 100°C instantly.

The best disinfectants are a 3% alkaline solution of formaldehyde (exposure 1 hour), a suspension of bleach containing 5% active chlorine, a 10% solution of iodine monochloride, a 20% suspension of freshly slaked lime (calcium hydroxide), a 5% solution of hypochloride calcium, 1% solution of glutaraldehyde and other drugs.

Epizootology. Many species of domestic and wild animals are susceptible to tuberculosis, including fur-bearing animals and birds (more than 55 species of mammals and about 50 species of birds). Cattle, pigs, and chickens are more sensitive to tuberculosis. Dogs, cats, ducks, and geese get sick less often, with the exception of horses, sheep, and donkeys. The source of the infectious agent is sick animals that secrete mycobacteria in feces, sputum, milk, and in case of damage to the genitourinary tract - with sperm. The causative agent of tuberculosis can persist in the body for a long time in the form of L-forms. Such animals often remain undetected sources of the causative agent of tuberculosis. Under unfavorable conditions, L-forms of mycobacteria can revert to their original form (the classical form of mycobacteria) and become the cause of tuberculosis.

Transmission factors for the causative agent of tuberculosis can be feed, water, pastures, bedding, manure, etc., contaminated with secretions of sick animals. Young animals become infected mainly through milk and skim milk obtained from sick animals. Intrauterine infection of calves is possible. Animals can become infected through contact with people with tuberculosis, especially milkmaids and calves. During the stalled period, adult cattle are infected mainly by aerogenic means, and on pastures - by nutritional means; pigs - nutritionally when feeding them undisinfected kitchen waste from hospitals, tuberculosis dispensaries or when in contact with sick birds. Dogs, cats - from sick people or when eating milk, meat from sick cows.

The massive spread of tuberculosis on farms is facilitated by factors that reduce the resistance of animals. These include: inadequate feeding, increased milk production without compensation for essential microelements, vitamins, and amino acids that are vital for the body; lack of regular exercise in the fresh air, cramped and damp rooms, unsanitary conditions for keeping animals.

Pathogenesis. Having penetrated the body with food or inhaled air, tuberculous mycobacteria enter the lungs or other organs through the lymphogenous and hematogenous routes. At the site where the bacteria are localized, an inflammatory process develops, followed by the formation of tuberculous nodules - tubercles the size of a lentil grain, grayish in color, and round in shape. In the center of the tubercle, dead cells under the influence of mycobacterial toxins turn into a curdled mass. In a benign course of the disease, the primary focus undergoes calcification, is surrounded by connective tissue, and further development of the infectious process stops. With a decrease in resistance, the process of encapsulation of the pathogen in the primary focus is weakly expressed, the walls of the tuberculous nodule melt, and mycobacteria enter healthy tissue, which leads to the formation of many new similar tuberculous nodules (miliary tuberculosis). Small tuberculous nodules can merge with each other, forming large tuberculous foci.

From such tuberculosis foci, mycobacterium tuberculosis can enter the blood, which leads to the generalization of the process and the development of tuberculosis foci of different sizes in various organs (liver, spleen, kidneys, etc.). With a generalized form of tuberculosis and extensive damage to the lungs, exhaustion and death of the animal occur.

Course and clinical manifestation. The duration of the incubation period for tuberculosis ranges from 2 to 6 weeks. Tuberculosis in animals is chronic or latent, so clinical signs of the disease may appear several months or years after infection. Animals infected with tuberculosis are detected mainly by allergic and serological research methods. Tuberculous lesions are usually detected only during post-mortem examination of organs, and the appearance of clinically pronounced forms indicates a long course of the disease. Clinical signs of tuberculosis are very diverse even in the same animal. Based on the location of the pathological process, pulmonary and intestinal forms of tuberculosis are distinguished; There are also lesions of the udder, serous integument (pearly mussel), genital form and generalized tuberculosis.

In cattle, tuberculosis most often affects the lungs and the tuberculosis process occurs chronically, in young animals - acutely and subacutely. Pulmonary tuberculosis is characterized by a strong dry cough, which gets worse when the animal stands up or inhales cold air; the temperature can rise to 39.5...40°C. Appetite and productivity are not reduced in the initial period. As the disease progresses, signs of inflammation of the lungs and pleura appear. The cough becomes painful, breathing is difficult and accompanied by groans. Wheezing can be heard in the chest, and areas of dullness can be heard on percussion.

Damage to the mammary gland is characterized by an enlargement of the superior lymph nodes, which become dense, lumpy, and inactive. When milking, watery milk mixed with blood or curdled mass is released. When the genital organs are damaged in cows, increased sexual heat and barrenness are noted, and orchitis in bulls. In generalized tuberculosis, superficially located The lymph nodes(mandibular, retropharyngeal, superior, knee folds) increase and become tuberous.

Tuberculosis in pigs is asymptomatic. Sometimes there is an increase in the mandibular and retropharyngeal lymph nodes. With extensive lung damage, coughing, vomiting, and difficulty breathing occur.

Sheep suffer from tuberculosis very rarely, goats - somewhat more often, but both are asymptomatic. With a highly pronounced process, the clinical signs in goats are similar to those in cattle.

In horses, the disease is rarely recorded, mainly in farms where cattle are unfavorable for tuberculosis. If the lungs are affected, a weak cough is noted, fast fatiguability; in the intestinal form - colic, diarrhea, followed by constipation, polyuria.

In birds (usually chickens, geese, ducks, turkeys), tuberculosis is chronic with unclear clinical signs. Sick chickens are inactive and quickly lose weight. The comb and earrings are pale, wrinkled, and atrophy of the pectoral muscles occurs. Prolonged debilitating diarrhea is possible. Birds die from exhaustion.

In fur-bearing animals (foxes, mink, nutria), tuberculosis most often affects young animals. Patients experience weakness and exhaustion; if the lungs are affected - cough, shortness of breath; in the intestinal form - profuse diarrhea.

Clinical signs of the disease in dogs and cats are uncommon; emaciation is observed, and if the lungs are affected, difficulty breathing and coughing are observed. Death occurs due to complete exhaustion.

Pathological signs. Tuberculosis is characterized by the presence in different organs and tissues of the animal of specific nodules (tubercules) the size of a millet grain to chicken egg and more.

In cattle suffering from long-term tuberculosis, the lymph nodes of the chest cavity are affected in 100% of cases, the lungs in 99%, the intestines in 10%, and other organs and tissues less frequently. Also characteristic are cavities in the lungs, formed during the disintegration of caseous masses and during the expansion of large bronchi. The bronchial and mediastinal lymph nodes are enlarged, dense, and riddled with tuberculous nodules. With intestinal tuberculosis, gray-yellow tubercles or round ulcers are found on the mucous membrane, oval shape with roller-like raised edges. Mesenteric lymph nodes are enlarged, compacted, with signs of cheesy degeneration.

In birds, tuberculous lesions are more often found in the liver and spleen, which are usually sharply enlarged, flabby in consistency, and contain numerous tubercles.

Diagnosis and differential diagnosis. The diagnosis is established based on the analysis of epizootic data, clinical signs and the results of allergic, pathological, histological, bacteriological and biological studies.

The clinical method for diagnosing tuberculosis is of limited value, since at the onset of the disease there may be no clinical signs at all. The main method of intravital diagnosis of tuberculosis is an allergic study.

For the study, an allergen is used - tuberculin - a sterile filtrate of killed cultures of the causative agent of tuberculosis of two types: dry purified (PPD) tuberculin for mammals and PPD tuberculin for birds. The latter is prepared from the causative agent of avian tuberculosis and is used to diagnose tuberculosis in birds and pigs.

The main method of intravital diagnosis of tuberculosis in animals is an allergic study using an intradermal tuberculin test. In horses, an eye examination method (ophthalmic test) is used. If necessary, it is also carried out in cattle simultaneously with an intradermal test.

Cattle (buffaloes) are subjected to tuberculinization from the age of 2 months, camels from the age of 12 months, deer and sika deer from the age of 6 months, fur-bearing animals and birds from the age of 6 months. If necessary, sheep, dogs and cats are examined.

With the intradermal method of tuberculinization, the drug is administered to cattle, buffalo, zebu cattle, deer (deer) - in the middle of the neck, bulls - into the sub-tail fold, camels - into the skin of the abdominal wall or into the groin area at the level of the horizontal line of the ischial tuberosity, pigs - in the area of ​​the outer surface of the ear 2 cm from its base, in goats - in the thickness of the lower eyelid; dogs, monkeys and fur animals(except minks) - to the area inner surface thigh or elbow crease; minkam - intrapalpebrally into the upper eyelid; for cats - in the area of ​​the inner surface of the ear; kuram—in the beard; for turkeys - in the submandibular earring; for geese and ducks - in the submandibular fold; for male pheasants - into the cavernous bodies of the head; peacocks, parrots, pigeons, cranes, herons, storks, flamingos - in the area of ​​the outer side of the lower leg, 1...2 cm above the ankle joint.

Before tuberculin is administered, the fur (hair) at the injection site is trimmed (feathers are plucked), and the skin is treated with 70% ethyl alcohol.

Accounting and assessment of the reaction to intradermal injection of tuberculin is carried out in cattle, buffaloes, zebu cattle, camels and deer after 72 hours; in goats, sheep, pigs, dogs, cats, monkeys, fur-bearing animals after 48 hours; in birds after 30...36 hours. In areas unfavorable for tuberculosis, cattle and camels are allowed to re-inject tuberculin 72 hours after the first injection in the same dose and in the same place. The response to repeated administration is recorded and assessed after 24 hours.

When taking into account the intradermal reaction, the site of tuberculin injection is palpated in each animal under study; in minks, the eyelids of the left and right eyes are visually compared.

If thickening of the skin is detected at the site of tuberculin injection in cattle, buffaloes, zebu cattle, camels, and deer, the thickness of the fold in millimeters is measured using a cutimeter and the magnitude of its thickening is determined by comparing it with the thickness of the fold of unchanged skin near the site of tuberculin injection.

Animals are considered tuberculin-responsive:

cattle and camels - when the skin fold thickens by 3 mm or more after the first injection of tuberculin and by 4 mm after repeated administration; buffalos, zebu cattle and deer - when the skin fold thickens by 3 mm;

stud bulls, sheep, goats, pigs, dogs, cats, monkeys, fur-bearing animals, birds - in case of swelling at the site of tuberculin injection.

Intradermal tuberculin test is a highly specific reaction to tuberculosis. However, it depends on the general immunoreactivity of the body. In animals of low fatness, old, deep-pregnant animals, as well as with a generalized tuberculosis process, the reaction to tuberculin may be weakly expressed or not manifested (anergy).

It should also be taken into account that nonspecific (para- and pseudoallergic) reactions to tuberculin for mammals are sometimes possible, due to sensitization of the body by mycobacteria of the avian species, the causative agent of paratuberculosis and atypical mycobacteria, as well as other reasons. To differentiate nonspecific reactions, a simultaneous allergy test is used, which is carried out simultaneously with tuberculin for mammals and a complex allergen from atypical mycobacteria (CAM). If the intradermal reaction to the introduction of CAM is more intense than to mammalian tuberculin, the reaction is considered nonspecific, and material from such animals is examined for tuberculosis using laboratory methods.

Tuberculinization by eye method carried out twice with an interval of 5...6 days. Tuberculin (3...5 drops) is applied with an eye pipette to the conjunctiva of the lower eyelid or to the cornea of ​​the eye. The reaction is taken into account after the first administration after 6, 9, 12 and 24 hours, after the second - after 3, 4, 6, 9, 12 hours. It is considered positive if internal corner the eyes begin to separate mucopurulent secretions, hyperemia and swelling of the conjunctiva appear.

If animals that react to tuberculin are detected for the first time in a prosperous farm, to clarify the diagnosis, 3...5 animals with the most pronounced reactions to tuberculin are slaughtered and internal organs and lymph nodes are examined. In the absence of changes typical for tuberculosis, pieces of organs and lymph nodes are selected and sent to a veterinary laboratory for bacteriological examination.

The diagnosis of tuberculosis is considered established: 1) when a culture of the tuberculosis pathogen is isolated or 2) when a positive result of a biological test is obtained; 3) in cattle, in addition, the diagnosis is considered established when detected in organs or tissues pathological changes, typical for tuberculosis.

Immunity and specific prevention. In case of tuberculosis, phagocytosis is incomplete, non-sterile immunity is formed, as a result of which it has no protective value. Specific prevention with the BCG vaccine is possible, but in most countries farm animals are not vaccinated against tuberculosis.

Prevention. Prevention and control measures against animal tuberculosis are carried out in accordance with the current Sanitary and Veterinary Rules. In prosperous farms, farms are stocked with healthy animals from tuberculosis-free farms; feed is purchased only from prosperous farms.

Newly received animals are examined for tuberculosis during a 30-day quarantine period. The skim milk supplied for feeding young animals is pasteurized, and the collected food waste is subjected to heat treatment. People with tuberculosis are not allowed to serve animals. Livestock premises are periodically disinfected, rodents and ticks are destroyed, and the feeding and living conditions of animals are improved.

For preventive purposes, routine diagnostic tests of animals for tuberculosis are carried out annually. Cows and sires are examined 2 times a year: in the spring, before being put out to pasture, and in the fall, before placing livestock in winter housing, and young cattle (starting from 2 months of age) and fattening groups - once a year; horses, mules, donkeys, sheep and goats - depending on the epizootic situation; all adult sows and young animals after weaning in all breeding farms, poultry stations - once a year. Animals owned by citizens are tested for tuberculosis at the same time this work is carried out on farms.

Treatment. Animals with tuberculosis are sent for slaughter. In herds, on farms, in populated areas, where the disease has already been established, animals that react to tuberculin are recognized as having tuberculosis and are also sent for slaughter within 2 weeks.

Control measures. When animals that react to tuberculin are identified in safe farms, they are further examined by performing an ophthalmic test or an intravenous tuberculin test; reacting animals are subjected to control slaughter; material from killed animals is sent to a veterinary laboratory for bacteriological testing for tuberculosis. When tuberculosis is detected, farms (farms, brigades, departments), as well as populated areas, are declared unfavorable for this disease, restrictions are introduced into them and an action plan is drawn up to improve the health of the affected area (farm).

The degree of disadvantage in cattle herds is determined taking into account the prevalence of the disease: limited - when a double tuberculin test detects up to 15% of sick animals from the population in the herd or on the farm; significant - when more than 15% of sick animals are detected.

The improvement of the health of cattle herds unfavorable for tuberculosis is carried out in the following ways: 1) systematically perform diagnostic studies with the isolation of sick animals or entire unfavorable groups with their subsequent slaughter; 2) simultaneously carry out a complete replacement of the population of a dysfunctional herd (farm) with healthy animals.

In both cases, it is mandatory to carry out a set of organizational, economic, veterinary and sanitary measures provided for in the instructions.

A one-time complete replacement of the livestock is carried out when tuberculosis is first established in a district, region, republic, and when the disease is significant in the herd (the disease is more than 15% of the livestock).

After the premises are cleared of livestock, they are disinfected and undergo veterinary and sanitary repairs. For disinfection on farms, the following are used: a suspension or clarified solution of bleach (5% active chlorine), a 1% aqueous solution of glutaraldehyde, a 3% alkaline solution of formaldehyde, a 5% solution of sodium phenolate. For aerosol disinfection, a 40% solution of formaldehyde is used with an exposure of 1 hour. Pastures where sick animals were grazed can be used after 2 months in the southern regions and after 4 months in the rest of the country.

After completion of veterinary and sanitary measures, final disinfection of all premises of the farm and laboratory testing of the quality of disinfection, restrictions are lifted from the unfavorable farm.

If less than 15% of the herd is infected with tuberculosis, recovery can be carried out by systematic research and slaughter of sick animals. All animals from 2 months of age are examined every 45...60 days with a double intradermal tuberculin test. At the same time, other species of animals (including dogs and cats) on the farm are tested for tuberculosis. Animals that react to tuberculin are recognized as sick, marked, isolated and slaughtered within 15 days.

When receiving two in a row throughout the herd negative results animal studies are subject to a 6-month follow-up period, during which two studies are carried out with an interval of 3 months. Upon receiving negative results of control studies and carrying out a set of veterinary and sanitary measures, the farm (herd) is declared free from tuberculosis.

If during a control study animals that react to tuberculin are isolated, they are all subjected to diagnostic slaughter. If pathological changes characteristic of tuberculosis are detected, further studies are carried out every 30...45 days, as indicated above.

Upon receipt of negative results of allergic and laboratory tests, the herd is declared free from tuberculosis and restrictions are lifted. Before restrictions are lifted, a set of veterinary and sanitary measures are carried out.

When tuberculosis in pigs (bovine or human pathogen) is detected in pig farms, all animals that react to tuberculin, including pregnant sows, boars, and fattening livestock, are sent for slaughter. Upon completion of farrowing and fattening, all animals on the farm are handed over for slaughter - no later than 6 months from the date of diagnosis of tuberculosis. After carrying out a set of veterinary and sanitary measures, restrictions on the farm are lifted.

When tuberculosis is diagnosed in horses, sheep and goats, all reacting animals are killed; the remaining livestock is examined: horses - by ophthalmic test, and sheep and goats - by intradermal test every 45...60 days until a single negative result is obtained, after which the animals of the corresponding group are recognized as healthy.

When tuberculosis is diagnosed in fur-bearing animals, they are subjected to a clinical examination, sick females along with their offspring are isolated. During the period of maturation of the skins, the animals are fed tubazide daily in a therapeutic dose. After slaughter, the skins are used without restrictions; for the rest of the animals in the disadvantaged group, tubazide is added to the feed in prophylactic dose. Minks are vaccinated with the BCG vaccine for preventive purposes; a fur farm is considered healthy if during the season from whelping to slaughter no changes in organs and tissues typical of tuberculosis are found in dead or killed animals; restrictions on the farm are lifted after carrying out veterinary and sanitary measures.

In poultry farms, when tuberculosis is diagnosed, all the birds from a dysfunctional poultry house (workshop) are handed over for slaughter, appropriate veterinary and sanitary measures are carried out, and after restrictions are lifted, a new flock of healthy pullets is formed. Eggs from birds from a dysfunctional poultry house (workshop) are not allowed for incubation and are used in bakery and confectionery production.

Control questions and tasks. 1. Epizootological features, etiology, course and forms of clinical manifestations of tuberculosis in animals of different species. 2. What requirements for the prevention of tuberculosis in animals and humans are imposed on animal owners, farm managers, local (district) SES centers and local doctors of rural (village) clinics (outpatient clinics), as well as veterinary specialists of agricultural enterprises? 3. Who and by what methods carries out epizootological control of the well-being of farms for tuberculosis? 4. Name the methods and means for specific diagnosis of tuberculosis in animals of different species. 5. What to do if a routine diagnostic test reveals several animals that react positively to tuberculin? When is a diagnosis of tuberculosis considered established? 6. In what cases is a simultaneous allergy test performed? Method of implementation and interpretation of its results. 7. What restrictive measures are carried out in areas where animals are unfavorable for tuberculosis? 8. Who declares a farm unfavorable for this disease and on the basis of what documents? 9. Draw up plans for health-improving measures in herds of cattle, pigs, sheep, goats, fur-bearing animals and poultry that are unaffected by tuberculosis. 10. What measures should be taken when tuberculosis is detected in the personal backyards of citizens?

Not everyone knows that not only humans, but also most domestic animals are susceptible to tuberculosis. This infectious disease involves several types of pathogens. And cattle are susceptible to several at once: human, bovine and avian. Moreover, if a cow does become infected, it quickly infects all surrounding animals and can be dangerous to humans. Therefore, it is so important to have at least a general idea of ​​how the disease develops, what its symptoms are and how to prevent it.

History of origin

Tuberculosis in cows is a widespread infectious disease in the world, the causative agent of which is Koch's bacillus (a special microbacterium). The disease usually affects the lungs, sometimes it develops in other internal organs. It appears in the form of small nodules that gradually cause tissue necrosis and can be fatal. Tuberculosis is transmitted by airborne droplets. People, birds, and domestic animals, including cattle, can be exposed to it.

Despite the fact that today the problem of the spread of the disease is extremely relevant, the history of tuberculosis is quite long. Officially confirmed sources indicate that signs of this disease were found during studies of ancient mummies from Egyptian pyramids. That is, this find proves that the disease existed several thousand years ago.

A little later in his works, Hippocrates described the symptoms of the disease, highlighting among them:

• severe cough with blood;
• hemorrhage in the lung area;
• general weakness and rapid exhaustion.

The scientist made assumptions that the disease was contagious, but never found reliable evidence for his theory. But, in 1865, the French scientist Jean-Antoine Villemin began studying the disease. He filled in some gaps in Hippocratic theory by proving that tuberculosis is an infectious disease. In addition, he proved that some animals are also susceptible to the disease, and accurately described the routes of transmission of infection from animal to animal and to humans.

A little later, the German scientist Robert Koch discovered that the causative agent of the disease was a group of microbacteria Mycobacterium tuberculosis, which was later called Koch's bacillus. Moreover, this group involves division into species, in accordance with the organism that is most susceptible to its action. This is how bovine, human, poultry, pork and other varieties are distinguished.

Reference. In 1902, the first case of bovine tuberculosis being transmitted to humans was officially recorded. This proved that regardless of the type, the pathogen can still cause disease in other species. This fact is another confirmation that tuberculosis in cows is an extremely serious and dangerous disease that requires immediate action.

Causes

There are many reasons why tuberculosis can develop. The causative agent of the disease is transmitted by airborne droplets. Therefore, if one cow is already sick, the infection quickly spreads to the entire herd. This happens especially often and at a rapid pace if cows are kept in a cramped barn, with a minimum amount of free space for each individual.

An animal can also become ill when kept in a stall where a sick individual was previously located. According to the results of the research, it was revealed that Mycobacterium bovis, the causative agent of tuberculosis in cows, is capable of living in soil for 2 years, but it dies in water only after 5 months. In manure and straw that is poured into stalls, the infection survives for several years. It is not affected by sub-zero temperatures and other climatic conditions. Therefore, there are quite a lot of infection options. Livestock can bring the bacteria from pastures, common watering places, and become infected from other domestic animals. Even animal care tools and staff clothing can cause illness.

Contributing factors for the development of the disease are dirt and unsanitary conditions in the premises, inadequate feeding, and too close housing. Often the cause of disease in cattle is also a person who has the disease in an open form.

Important! IN in some cases Another cause of tuberculosis is insufficient treatment of the newly acquired premises in which animals are planned to be kept. Microbacteria of the disease can live in the soil under the floor or in the pasture. Accordingly, healthy animals coming into contact with them quickly become infected and spread the infection.

Symptoms

When a pathogen enters a cow’s body, it goes through an incubation period, which can last from 2 to 6 weeks. At the end of this period, the infection begins to develop. In this case, the disease in cattle most often develops latently. This means that symptoms indicating a pathogenic condition may appear only after a few months or a couple of years.

Depending on the location of the infection by microbacteria, tuberculosis in cows is divided into several types. The most common among them are:

• pulmonary tuberculosis;
• intestinal variant;
• udder damage;
• infection inside the uterus;
• generalized form. It involves the dissemination of infection through the blood, as a result of which it affects several organs or systems at once.

The location of the source of the disease also determines how contagious the animal is. With tuberculosis of the udder, uterus, and intestines, pathogens are released into the environment with feces or milk. Accordingly, the spread of the disease among other individuals or even the spread to humans can be traced. In some cases, an active type of infection is also observed in pulmonary tuberculosis. But more often it passes latently.

The main problem in diagnosing the disease in cattle is that in adults it is mostly hidden. Acute form infections can be traced only in young cows.

In general, the following changes in an animal may be symptoms of tuberculosis:

• frequent or constant shortness of breath;
• sudden weight loss and loss of appetite;
• dry skin and decreased elasticity;
• constantly elevated temperature. Typically it ranges from 39 to 40.5 degrees;
• cough with mucus. A careful examination of mucous secretions may reveal tissue remains that have undergone necrosis;
• if you listen to the animal’s chest, you can detect clearly defined wheezing in it;
• a sharp increase in the retropharyngeal glands, which is accompanied by copious secretion of saliva and mucus from the nose. Severe swelling may also be accompanied by suffocation.

Specific symptoms

There are also a number specific symptoms, which can be traced only with a certain type of tuberculosis. Thus, if the pleura of the lungs is damaged, the cow will react sharply to pressure between the ribs due to pain.

If the udder becomes infected, it swells significantly in the back. In this case, the swollen area becomes hard and also causes painful sensations when pressed. Milk containing blood particles may be released from the nipples. Also in this case, the superior lymph node will be greatly enlarged. Individual nipples may be wrinkled and deformed.

If the focus of the disease is concentrated in the intestines, the animal experiences periodic diarrhea, which gradually develops into permanent diarrhea. Against the background of indigestion, general exhaustion of the body with weight loss quickly develops. Impurities of blood and pus can be observed in the stool.

Damage to the uterus or genital organs of a cow is often accompanied by abortion and infertility. In males, infection of the genital organs with tuberculosis causes them to become swollen and inflamed.

The main symptom of the generalized type of disease is inflammation and an increase in the size of all lymph nodes on the body of livestock. When inflamed, they harden and cause severe pain to the animal when pressing on them with your fingers. The easiest places to palpate are the cervical, suprauterine, parotid, inguinal and knee fold nodes. At serious development diseases they grow to such an extent that they can be seen even during an external examination.

Also, although extremely rare, brain tuberculosis can be traced in cattle. Usually it is a consequence of a generalized form. This process is accompanied by frequent paralysis, anxiety of the animal, and severe agitation.

But it is worth noting that in cows, the disease without symptoms can last for years, so external signs are a rather unreliable way to identify the disease.

Diagnostics

Diagnosis of tuberculosis in large and medium-sized farms is carried out periodically on a regular basis. The main method of such diagnosis is allergic testing - teberculinization. To implement this, the animal is injected with a solution of PPD tuberculin with sterile pathogens that are grown under artificial conditions. This drug can be administered to individuals older than 2 months. The test does not affect pregnancy in cattle and can be carried out at any stage.

The whole procedure goes as follows:

1. A small area of ​​skin is cut off on the infra-tail fold of bulls, in the middle of the neck of a cow, or in the area of ​​the shoulder blade of young animals. After this, it is treated with 70% ethyl alcohol.
2. The drug is injected into the prepared area with a syringe at a dose of 0.2 ml.
3. Then the animal is left alone for 72 hours.
4. At the end of the specified term, diagnostic results are carried out, according to which the animal is classified as responding to tuberculin or not responding.

Diagnostic results

Evaluation of the results of injection is carried out by external examination and palpation. If swelling is found at the injection site, it is measured. If the skin fold increases by 3 mm or more, the individual is considered responsive. An increase in skin temperature in the injection area and painful sensations in the animal are also considered a positive result.

If the results are ambiguous, a repeat sample is allowed. In this case, a specialist will carry out the inspection within 24 hours. Using this method involves administering tuberculin to the entire farm population, without exception. The procedure is carried out twice a year, in spring and autumn.

It is worth noting that during allergy testing, controversial results may arise. They are caused by the activity of another type of microbacteria. Therefore, tuberculinization is sometimes supplemented with an eye or intravenous test. During an eye test, tuberculin in a volume of 3-5 drops is injected under the lower eyelid and into the conjunctival sac of the animal. A positive reaction is considered to be the occurrence of purulent conjunctivitis 8-9 hours after the injection.

The second method involves injecting the drug into a vein. At the same time, the cow’s temperature is measured every 3 hours. If the value rises by 0.9 degrees or more compared to the original value, it means that a human or bovine type pathogen is present in the body.

A positive and pronounced reaction to any of the tests using tuberculin requires a pathological examination. To do this, several individuals with such indicators are selected for diagnostic slaughter. Next, specialists examine the internal organs and tissues of the animals. If signs of pathological changes inherent in tuberculosis have been identified, the exact type of pathogen is determined and further measures are determined. If no damage is detected, a sample is taken for bacteriological examination in the laboratory.

Treatment

To date, there is no effective veterinary medicine against tuberculosis in cattle. Therefore, it is not possible to cure infected cows. Depending on the identified results, a farm may be classified as prosperous or unfavorable.

By decision of the district administration, a number of restrictions are imposed on a disadvantaged herd that prevent further dissemination diseases. In addition, such a farm is assigned a specialist who is responsible for the clear and steady implementation of measures to suppress the development of infection.

Health work in the herd is carried out in two main ways:

1. Frequent periodic samples and laboratory tests, during which all infected individuals on the farm are isolated. Then they are sent for slaughter.
2. Complete replacement of the herd with healthy animals with accompanying work on disinfection of the holding area.

The first method involves periodic checks with an interval of 60 days and the culling of individuals that react positively. Recovery is carried out until all animals from the dysfunctional herd show a negative result. In this case, restrictions on the farm are lifted, and the herd is considered healthy.

The second method is used if the percentage of cows that reacted positively is 15% or more of the total livestock of the farm. In this case, the farm is quarantined and the following measures are taken:

1. All examinations are stopped.
2. All livestock kept on the farm, including young animals, are sold for slaughter.
3. Milk obtained from animals is boiled in full at a temperature of 90 degrees for 5 minutes.
4. All premises in which livestock were kept are cleaned of dirt, feed, and manure. After this, the floor covering is removed, and the freed area is treated with a solution of formaldehyde and caustic salt. For every square meter of area, at least 1 liter of liquid should be consumed. This mixture can also be replaced with a lime solution with a concentration of 5% active chlorine.
5. Old flooring and all garbage from the site are collected and transported outside the farm.
6. If the floor was laid directly on the ground, and not on a cement base, upper layer soil, 15-20 cm thick, must be selected and taken to the place indicated by the veterinary inspector.
7. Manure is also transported there. If necessary, it can be used again, but not earlier than after 2 years of storage.
8. All equipment used to service livestock is also subject to disposal.

Upon completion of all the above work, the premises are restored, floors are laid, and feeders are installed. Next comes their re-processing. After disinfection is completed, samples are taken from the farm for the presence of pathogens. If confirmation is received that all infection was destroyed during the cleaning process, the quarantine from the farm is removed. At the same time, the owner is free to start a new herd. To do this, he makes purchases from farms that are listed as safe by the veterinary service.

At the same time, the new herd is again tested with tuberculin. The first time a sample is taken 15 days before removal from a safe farm. The second time the test is carried out after 15 days of living in new conditions. The third and fourth involve control checks every 30-45 days.

In addition to the farm itself, quarantine is also imposed on the pasture on which the disadvantaged herd was grazed. Animals are allowed there again no earlier than after 2 years.

Prevention

From all of the above, it follows that high-quality preventive measures are the only effective means protection of cattle from tuberculosis. For the purpose of prevention, farm owners should:

1. Observe hygiene standards when keeping, feeding, and transporting livestock.
2. Pay careful attention to the feed preparation process. Purchase only from reliable, verified sources.
3. Register all purchased animals at the regional veterinary institution.
4. Within 30 days, quarantine the purchased livestock and request testing from the veterinary service.
5. Closely monitor the condition of all livestock and, if available, the slightest symptoms the occurrence of illness, seek help from a veterinary institution.
6. Pasture, purchase, transportation, sale, sale of dairy and meat products must be carried out only after obtaining permission from the veterinary department.
7. Organize a survey of the entire livestock twice a year, in spring and autumn.
8. Examine yourself for the presence of pathogens in the body.
9. It is obligatory to hand over for slaughter within 2 weeks all cows that were rejected by the veterinary department.
10. Do not allow people who have tested positive to work.
11. When purchasing a farm plot with already built premises for keeping animals, carry out a thorough treatment with disinfectants. The same must be done with all the equipment available on the farm.

In addition, quite often young cattle become infected with tuberculosis while drinking skim milk or regular milk. Therefore, to avoid infection, dairy products must be pasteurized before serving to animals.

Also an important preventive point is periodic disinfection of the premises in which cows are kept. Additionally, it is necessary to constantly combat emerging rodents.

Conclusion

Tuberculosis can cause the loss of the entire livestock of a farm, thereby negating all the many years of work of its owner. In addition, humans can also become infected from infected animals. That is why it is necessary to approach with all responsibility the observance of preventive measures on the farm, and if detected, even the slightest sign illness, immediately seek help from a veterinary service. Attempts to solve the problem yourself can provoke a large-scale epidemic.

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Ministry of Agriculture and Food of the Republic of Belarus

EE "Vitebsk Order of the Badge of Honor" State Academy of Veterinary Medicine

Department of Epizootology and Infectious Animal Diseases

Tuberculosis of farm animals

VITEBSK 2010

Definition of disease

Tuberculosis is a chronic infectious disease of most species of animals and humans, characterized by progressive emaciation and the formation in organs and tissues of specific nodules - tubercles, prone to cheesy necrosis and calcification. Historical background. The disease has been known since ancient times. Hippocrates in the 4th century. BC e. described the clinical signs of tuberculosis in humans. The name of the disease “tuberculosis” was introduced by K. Lenek (1819). The contagious nature of the disease was proven by J. A. Villemin in 1865. The causative agent of tuberculosis was discovered by R. Koch in 1882, and in 1890 he developed a method for producing tuberculin. Bacteriologist A. Calmette and veterinarian S. Guerin in 1924 produced the BCG vaccine (BCG - Bacillus Calmette - Guerin) for the specific prevention of tuberculosis in humans. Tuberculin was first proposed for the diagnosis of tuberculosis in animals by R. G. Gutman in 1891.

Spread of the disease

Tuberculosis is common in many countries of the world. In developed countries of Europe and North America, the disease has been virtually eliminated. In the Republic of Belarus, tuberculosis is not widespread (1-3 unfavorable points for tuberculosis in cattle are registered annually). However, the problem of tuberculosis remains relevant to this day.

Economic damage

The disease causes great economic damage, which, when tuberculosis occurs, consists of the costs of carrying out quarantine or restrictive measures, and slaughtering productive animals that react to tuberculin. Large costs are also associated with carrying out preventive measures, including annual allergic tests of animals in tuberculosis-free farms. The social significance of tuberculosis is enormous. Every year, about 10 million people worldwide fall ill, of whom 3.5 million die from this disease. The epidemiological situation regarding tuberculosis is difficult in the Republic of Belarus. In this regard, it is believed that tuberculosis is more a medical problem than a veterinary one, and the disease itself is classified as an anthropozoonosis. An entire branch of medicine deals with this disease - phthisiology (from the gr. phthisis - exhaustion, consumption).

Etiology

The causative agent of tuberculosis belongs to the genus Mycobacterium, which includes both pathogenic and non-pathogenic (atypical) species of mycobacteria. Tuberculosis in mammals is caused by M. tuberculosis (human species), M. bovis (bovine species), and in birds - M. avium (avian species). M. bovis causes tuberculosis in cattle, pigs, mink, deer and humans. M. tuberculosis is pathogenic for humans and pigs, and can infect cattle, but the disease in this case proceeds latently, usually without visible changes in the body. M. avium causes disease in birds and can cause tuberculosis-like lymphadenitis in pigs. M. murium causes disease in mice, M poikilotermorum - in cold-blooded animals, M. paratuberculosis - paratuberculosis in cattle. Non-pathogenic mycobacteria are widespread in nature; when they enter an animal’s body, they cause sensitization, which manifests itself in the form of paraallergic reactions to tuberculin. Morphologically, the causative agents of tuberculosis are rods 0.6 microns in width and 1-6 microns in length, immobile, do not form spores or capsules, aerobes have a well-developed cell wall. This is the basis of the Ziehl-Neelsen differential staining method, as a result of which mycobacteria are stained ruby ​​red, and all other microorganisms are blue. Tuberculosis pathogens grow slowly when cultured from pathological material. Colonies of bovine Mycobacterium tuberculosis appear only after 20-60 days, and avian ones - 15-30 days after sowing. It is recommended to keep the crops in a thermostat in the absence of mycobacterial growth for at least three months. To isolate tuberculosis pathogens, complex solid nutrient media are used: Levenshtein-Jensen, Gelberg, Petragnani, FLST-Zl, VKGidr. The causative agent of human tuberculosis forms polymorphic colonies, often having a cream color, but in most cases it cannot be distinguished from M. bovis by the appearance of the colonies. M. avium grows in the form of smooth, shiny, often turban-like colonies that emulsify well in aqueous solutions (S-form colonies). The species of mycobacteria is determined by biochemical properties and the degree of pathogenicity for laboratory animals. The pathogenicity of mycobacteria for laboratory animals is determined by subcutaneous or intravenous administration 1 mg (wet weight) of bacterial mass of a 3-4 week culture to three rabbits, three guinea pigs and three chickens. Under the influence of unfavorable factors (antibiotics, lysozyme, etc.), the causative agent of tuberculosis may lose the ability to synthesize the peptidoglycan skeleton of the cell wall, resulting in the formation of L-forms (transformed mycobacteria) with low virulence and capable of surviving in unfavorable conditions. L-forms of mycobacteria can persist for a long time in animals and humans. Transformed mycobacteria in some cases are capable of reverting to the classical forms of the pathogen, causing a relapse of the disease; to identify them, a special Shkolnikova medium, VKG medium with a growth stimulator, is used. The presence of waxy substances in the shell of mycobacteria determines the high stability of mycobacteria in the external environment. Mycobacteria persist in soil for up to 5 years; in manure, litter - up to 1.5 years; in water - up to 10 months, in feces, on pastures, frozen meat - up to a year; in butter, cheeses - up to 10 months. In milk, when heated to +85 °C, the pathogen dies after 30 minutes, and when boiled, after 5 minutes. Pasteurization of milk from cows reacting to tuberculin is carried out at +90 °C for 5 minutes, at +85 °C for 30 minutes. The most effective disinfectants are a 3% alkaline solution of formaldehyde and 5% solutions of chlorine-containing drugs. It is recommended to use Vitan, KDP (combined surface disinfectant), Belstril, Glutex and other agents for tuberculosis.

Epizootological data

More than 55 species of mammals and about 25 species of birds are susceptible to tuberculosis. Most often, cattle, pigs, and poultry - chickens suffer from tuberculosis. Goats, dogs, ducks and geese get sick less often. Sheep, horses and cats are very rarely affected by tuberculosis. Of the wild animals, deer are the most likely to get sick. Susceptibility to tuberculosis depends on the level of the animal’s immune status and the degree of negative impact of various stress factors on its body (hypothermia, low level feeding, microclimate disturbance, etc.). A higher susceptibility to tuberculosis has been established in highly productive animals and black-and-white breeds of cattle. Relative resistance to tuberculosis has been established in beef breeds of cattle. An important issue is the susceptibility of different species of animals and humans to different types of mycobacteria. Animals infected with avian Mycobacterium tuberculosis may respond to mammalian tuberculin. People can become infected with all types of mycobacterium tuberculosis, but more commonly human and less commonly bovine. When people become infected with avian mycobacteria, an acute onset of the disease is sometimes observed. Tuberculosis in dogs and cats can be caused by all three types of mycobacteria. The source of the infectious agent is animals with tuberculosis, and less often humans. Mycobacteria are excreted from the body in sputum, exhaled air, feces, milk, and rarely in urine and semen. The intensity of the division of the pathogen with various secretions and excreta depends on the location and nature of the tuberculosis process. Transmission factors include air, feed, water, bedding, manure and other objects contaminated with the pathogen. Infection of animals occurs through nutritional and aerogenic routes. The disease spreads slowly among animals, with massive re-infection occurring within 1-2 years. Epizootic situation regarding tuberculosis in the Republic of Belarus in the present time is characterized by the presence of single disadvantaged points per year. A peculiarity of the epizootic situation regarding tuberculosis and the republic is that the bulk of reacting animals are identified in farms that are free from tuberculosis. Tuberculosis in animals occurs in the form of enzootics, the infection rate of animals can reach 40-80%, sick animals die in in rare cases.

Pathogenesis

In a resistant organism, having penetrated the lungs or other organs, mycobacteria multiply and cause tissue irritation and inflammation. At the site of the future tubercle, leukocytes appear around tuberculous mycobacteria. They phagocytose and partially destroy microbes, but at the same time die themselves. Subsequently, cells such as monocytes and histiocytes multiply in this area, which begin to absorb mycobacteria and, in turn, become necrotic, but along the periphery of the inflammatory focus these cells differentiate into lymphoid, epithelioid and giant. In a typical tubercle in the center there is a necrotic area in the form of a structureless oxyphilic mass with fragments of nuclei and often with particles of lime. This area is limited by granulation tissue, consisting of two zones: the inner zone of epithelioid and individual giant cells and the outer zone of lymphoid cells. Exudate is deposited between the cells and fibrin coagulates. An avascular tuberculous nodule is formed, which is subsequently encapsulated. Due to lack of inflow nutrients and under the influence of bacterial toxins, the tissue cells in the tubercle die and a curdled mass is formed, impregnated with lime salts. Tuberculosis bacteria in such a nodule can die, and sometimes persist for a long time. In this case, the disease does not manifest itself clinically, and the animal appears healthy in appearance. If the body’s resistance is reduced, the capsule is not formed or is not strong enough, the pathogen is primary focus penetrates into the surrounding tissues, where new nodules form. They merge with each other, forming large tuberculous foci. The pathogen can enter the blood, which leads to a generalization of the process with the development of tubercles in various organs and tissues. In cattle, the serous membranes may be affected with the formation of dense shiny growths (pearly mussel). In the generalized form of tuberculosis in sick animals, gas exchange is disrupted, anemia develops, hematopoietic processes are inhibited, and exhaustion and death of the animal occur.

Course and symptoms of the disease

Clinically, tuberculosis in animals currently practically does not manifest itself, since the infectious process with tuberculosis develops slowly, and thanks to regularly scheduled allergic tests, sick animals are identified early stages diseases when clinical signs do not have time to develop. Duration incubation period for tuberculosis it is 2-6 weeks. The course of the disease is chronic or latent. There are generalized, pulmonary, intestinal and genital forms of the disease. There may be damage to the udder, genitals and serous membranes (pearl oyster). With the pulmonary form in cattle, a rare, but painful cough, shortness of breath, decreased appetite, decreased productivity and nutritional status. Damage to the udder is characterized by an increase in the supra-udder lymph nodes, and in the udder parenchyma - the formation of dense, painless foci. Milk is watery and contains blood or a curdled mass. The genital form is manifested by increased sexual heat, barrenness, and in bulls - orchitis. In the generalized form of tuberculosis, the superficial lymph nodes are enlarged, lumpy, and inactive. In pigs the disease is asymptomatic. An increase in the submandibular and retropharyngeal lymph nodes may be observed. Tuberculosis in small cattle is predominantly asymptomatic.

Pathological changes

Characteristic of tuberculosis is the formation in various organs and tissues of a sick animal of specific nodules (tubercules) the size of a millet grain to a chicken egg or more. They can form in almost all organs and tissues, except horny ones. However, in cattle the following are most often affected: lymph nodes of the chest cavity - in 100%, lungs - in 99%, liver - in 8%, spleen - in 5%, udder - in 3%, intestines - in 1% of cases.

In the lungs, tubercles are most often found along the blunt edge of the diaphragmatic lobe. The tubercles are dense, grayish or grayish-yellow in color with a cheesy mass in the center (caseous necrosis), partially or completely calcified, surrounded by a connective tissue capsule. The liver, kidneys, spleen and mammary gland are affected in the generalized tuberculosis process. Tuberculous changes in the serous integument of the thoracic and abdominal cavities (pearly mussel) are also recorded in generalized tuberculosis in cattle. No pathological changes are found in cattle sick with tuberculosis if they are infected with mycobacteria of human and avian species. In pigs, tuberculous lesions are most often found in the lymph nodes of the mesentery and head, less often in other organs. In horses, tuberculous changes are more often found in the lymph nodes of the mesentery of the head, mediastinal and less often in other lymph nodes.

Diagnostics

It should be carried out comprehensively, taking into account epizootological data, clinical signs, results of allergic studies, pathological autopsy and laboratory tests. Epizootological and clinical diagnostic methods are poorly informative. The pathoanatomical method in cattle (only in this type of animal) provides grounds for making a final diagnosis of tuberculosis (by commission), when pathological changes in organs and tissues typical for tuberculosis are detected. The diagnosis of tuberculosis based on the pathological method cannot be established in other animal species due to the atypicality of their pathological changes. The main method of intravital diagnosis of tuberculosis is allergic, for which the following tuberculins are used:

PPD tuberculin for mammals, which is produced in two types: in the form of a standard solution and dry tuberculin. In the form of a standard PPD solution, tuberculin for mammals is a sterile filtrate of a culture of the causative agent of bovine tuberculosis and its waste products grown on a synthetic Soton nutrient medium. Dry PPD tuberculin for mammals is a sterile filtrate of a culture of the causative agent of bovine tuberculosis and its waste products, grown on a synthetic Soton nutrient medium and subjected to lyophilic drying. There are: intradermal, palpebral (in the thickness of the eyelid) and ocular tuberculin tests. When carrying out intradermal tuberculinization, animals are examined for tuberculosis starting from two months of age. Cows are examined regardless of the period of pregnancy. Females of other animal species - 1-2 weeks after birth. Animals are not allowed to be examined within 3 weeks after vaccination against infectious diseases. Before the introduction of tuberculin, the hair of the animals is cut off, the skin is treated with 70% ethyl alcohol - 1 ml per treatment. Tuberculin is administered intradermally, in a dose of 0.2 ml, to a large cattle-in in the middle of the neck, at the intersection of the longitudinal and transverse lines, to the bulls in the sub-caudal fold. For pigs - injected in the area of ​​the outer surface of the ear, 2-3 cm from its base, while tuberculin for mammals is injected into the skin of one ear, and tuberculin for birds is injected into the skin of the other ear. For pigs aged 2-3 months, it is better to inject tuberculin with a needle-free injector into the skin of the lumbar region, left and right, 5-8 cm from the spine. In goats and sheep, tuberculin is administered palpebrally (into the thickness of the lower eyelid), departing from the edge by 1.5-2 cm (in a dose of 0.2 ml). Accounting for the results of tuberculinization: in cattle - after 72 hours; in pigs, sheep and goats - after 48 hours. In cattle, the site of tuberculin injection is palpated. When a swelling is detected, regardless of its nature, its thickening is determined by comparing it with the thickness of the fold of unchanged skin near the site of tuberculin injection. Thickening of the skin fold is measured with a cutimeter. In sheep and goats, when reading the palpebral tuberculin test, the eyelids of the left and right eyes are compared. In other animal species (pigs, etc.), the site of tuberculin injection is palpated and inspected. Based on the results of recording the reaction, animals are divided into:

responsive to tuberculin;

not responding to tuberculin.

The following are considered responsive: cattle (except bulls) - when the skin fold thickens by 3 mm or more, regardless of the nature of the swelling (swelling, pain, increased local temperature). In bulls (oxen), goats, sheep, pigs - when a noticeable swelling forms at the site of tuberculin injection. In farms that are unfavorable for tuberculosis in cattle, including those belonging to the population, it is allowed to use a double tuberculin test for a more complete identification of sick animals. In these cases, for animals that do not respond to the first injection of tuberculin, the drug is administered to the same place and in the same dose after 72 hours, i.e., when the reaction is read. The response to repeated administration of tuberculin is taken into account after 24 hours and assessed as above. The ocular tuberculin test is used to diagnose tuberculosis in horses. In cattle, it is used only simultaneously with intradermal testing in farms unaffected by tuberculosis for additional identification of infected animals. The ocular tuberculin test is carried out twice with an interval of 5-6 days between the first and second administration of tuberculin. Tuberculin in an amount of 3-5 drops is applied with a pipette to the conjunctiva with the lower eyelid retracted. Recording and evaluation of the reaction is carried out 3, 6, 9 and 12 hours after repeated administration of tuberculin. In animals reacting to tuberculin, the following is noted: hyperemia and possible swelling of the conjunctiva, accumulation of m conjunctival sac purulent and mucopurulent secretion and its flow out from the inner corner of the eye in the form of a cord. In the republic, an intravenous allergy test is not used to diagnose tuberculosis due to the possible sensitization of the animal body after its use. When responsive animals are identified in a tuberculosis-free farm, a simultaneous test with KAM or PPD-tuberculin for birds is carried out to differentiate paraallergic reactions to tuberculin. PPD-tuberculin for mammals and CAM are injected intradermally into symmetrical areas of the neck from different sides. When taking into account the reaction after 72 hours, the intensity of the reactions is compared. A reaction only to tuberculin for mammals or a more intense one to this drug is assessed as “+”. A reaction with the same thickening of the skin fold is assessed as "=", and with a more pronounced reaction to an allergen from non-tuberculous mycobacteria as "-". Statistical processing of the results is carried out in accordance with the current instructions. When cattle are infected with atypical mycobacteria, the number of animals reacting with a “-” score is 2-6 times greater than the number of animals with a “+” and “=” score. A significant number of animals with a sample score of "+" and "=" indicates the likelihood of infection with the causative agent of bovine or bovine tuberculosis human species, and therefore such animals must be submitted for diagnostic slaughter. The reliability of the simultaneous test is 77-100%. If, during routine allergy studies in tuberculosis-free farms, animals that react to tuberculin are identified, then the animals with the most pronounced reactions (5-10 animals) are subjected to diagnostic slaughter. In the absence of characteristic pathological changes, material is taken from the killed animals for bacteriological examination. For bacteriological examination, lymph nodes from mammals are sent to the laboratory: retropharyngeal, submandibular, bronchial, mediastinal, portal, mesenteric, taken in the area of ​​the ileocecal junction and ileum; pieces of organs with changes suspicious for tuberculosis. Paired lymph nodes are cut out from both sides of the carcass, indicating their name on the label, which is packaged with the sample. Carcasses (corpses) of birds and small animals are sent to the laboratory as a whole for research. Samples of pathological material selected for bacteriological examination are delivered to the laboratory fresh or frozen. Preservation of samples with a 30% sterile aqueous solution of chemically pure glycerin is allowed. The laboratory conducts bacteriological examination of the material, including microscopy, isolation of pure culture and infection of laboratory animals. For microscopic examination 2 smears are prepared from each organ and lymph node and stained with Ziehl-Neelsen. For fluorescence microscopy, smears are stained with a mixture of fluorochromes. Pathological material for cultural and biological studies is processed by the Gone-Levenshtein-Sumiyoshi method or the Alikaeva method. For the cultivation of Mycobacterium tuberculosis, solid egg, Levenstein-Jensen, Gelberg and Petragnani nutrient media are used. Biological research (bioassay) is used to detect the causative agent of a disease in the material under study and determine its species. Guinea pigs, rabbits and chickens are used for bioassays. The diagnosis of tuberculosis is considered definitively established in one of the following cases:

when changes typical of tuberculosis are detected in organs and tissues (only in cattle);

when isolating a culture of the causative agent of tuberculosis of bovine or human species;

upon receipt of positive results from a biological test.

In addition, methods for diagnosing tuberculosis using ELISA and PCR have been developed, allowing for intravital diagnosis of the disease by examining blood or bronchial mucus, as well as using the VKG medium with subsequent differentiation of mycobacteria grown on it.

Differential diagnosis

Animals with tuberculosis are not treated and are subjected to forced slaughter.

Immunity and specific prevention.

The immune system for tuberculosis is not sterile. The BCG vaccine is only allowed for immunization of fur-bearing animals. There are no specific preventive measures for other animal species.

Measures to prevent and eliminate the disease

tuberculosis agricultural animal disease

To prevent tuberculosis, it is necessary to comply with veterinary and sanitary rules for keeping, feeding and exploiting animals.

II Animals should be purchased only from farms that are free from tuberculosis (TB in cattle for at least 4 years, in pigs for at least a year). Imported animals are quarantined for 30 days with mandatory allergy testing for tuberculosis. Animals can be introduced into the herd only if negative results of allergic tests are obtained in all animals. Adult cattle (cows, sires, heifers older than one year) are routinely subjected to allergy testing twice a year (spring and autumn), and young cattle over two months of age. Sows and boars in breeding organizations are examined once a year, other species of susceptible animals - depending on the epizootic situation. Birds older than 2 years of original lines and ancestral flocks at breeding factories and breeding poultry stations are examined once a year. Identification of animals (birds) reacting to tuberculin on a tuberculosis-free farm is a sign of suspicion of tuberculosis, and in such cases the following measures are taken. If up to 10 animals reacting to tuberculin are detected on a farm, they are slaughtered, followed by examination of internal organs and tissues. If more than 10 animals reacting to tuberculin are isolated, at least 5 animals with the most pronounced reactions to tuberculin are slaughtered, followed by examination of internal organs and tissues. If visible changes typical of tuberculosis are detected in at least one carcass, the diagnosis is considered established, the responders are recognized as sick, and the farm is declared unfavorable for tuberculosis. It is also necessary to regularly thoroughly disinfect the premises. When tuberculosis in cattle is established on a dysfunctional farm, quarantine is introduced; for other types of animals, restrictions are imposed. Quarantine measures include a ban on: the import and export, with the exception of slaughter, of animals from a dysfunctional economy (farm); removal of feed; carrying out various events associated with the accumulation of animals; regrouping of animals without the permission of veterinary specialists; use of sick animals for herd reproduction; sale of sick animals to the public; export of untreated milk. Improving the health of a herd that is unfavorable due to bovine tuberculosis can be carried out in several ways: completely replacing the unfavorable herd; systematic diagnostic studies; accelerated method. The choice of healing method depends on the well-being or degree of disadvantage of the area. Tuberculosis-free areas are areas where there have been no cases of tuberculosis in animals for 4 years or more. Unfavorable areas are those areas where up to 10% of sick animals are detected; with limited spread of tuberculosis - up to 25%; with significant distribution - more than 25%. When the disease is detected in cattle in a prosperous area or when tuberculosis is significantly widespread, recovery is carried out by completely replacing the livestock. All animals, including the young animals assigned to them, are sent for slaughter within 6 months. Cows and heifers are not inseminated. IN dysfunctional farms for tuberculosis in cattle located in disadvantaged areas, when up to 25% of the livestock becomes ill on a farm, recovery is carried out by removing from the herd and slaughtering sick animals identified during systematic studies of disadvantaged livestock. In this case, all animals on a dysfunctional farm are examined every 60 days with an intradermal tuberculin test until two consecutive negative results are obtained, the reacting animals are sent for slaughter within 15 days, and the premises are disinfected. If a double negative result is obtained in a row, the animals are left under control observation for 6 months. During this period, two control studies with a tuberculin test are carried out with an interval of three months. If the results of these studies are negative, taking into account the implementation of a set of veterinary, sanitary and economic measures, the herd is considered healthy. If the improvement of the farm is not achieved by the specified method within two years, then the method of completely replacing the dysfunctional livestock with healthy livestock is used. After boiling, milk (cream) from cows that react to tuberculin is used as animal feed, and from non-responding animals it is pasteurized at +90 °C for 5 minutes or at a temperature of +85 °C for 30 minutes. Calves from animals reacting to tuberculin are sent for slaughter. Before they are placed under controlled observation, heifers and bull calves born from cows that do not respond to tuberculin are kept in a separate group, raised, not tested for tuberculosis, and then slaughtered. It is prohibited to keep heifers obtained from cows from a dysfunctional farm for reproduction. Young animals obtained from cows during the control observation period are kept isolated from adult cattle. If the farm is recognized as healthy, the young animals are raised as usual. At complexes for raising heifers, producing beef and in other fattening organizations, when tuberculosis is established, all animals of the disadvantaged group are branded with the letter “T” and handed over for slaughter for 30 days. The remaining livestock is examined every 60 days for tuberculosis using the allergic method or the issue of selling all the animals of the complex (farm) for meat is decided. During the summer grazing period, livestock are removed from dysfunctional farms and camps are carried out. Healthy livestock may be brought into premises that previously housed sick animals (unhealthy livestock) only after thorough mechanical cleaning, soil removal, sanitary repairs, three-time disinfection of premises, walking yards, as well as disinfestation and deratization. Manure is subjected to biothermal disinfection or kept in piles for at least two years; the use of other disinfection methods is allowed. In the absence of pathological changes characteristic of tuberculosis and negative results of bacteriological studies, the herd is considered recovered from tuberculosis. In pig farms where pigs are infected with mycobacteria of bovine or human species, all reacting pigs, including pregnant sows, boars, and fattening livestock are immediately slaughtered. Non-responsive pregnant sows are donated after weaning their piglets. A period of 6 months is allotted for eliminating the outbreak of tuberculosis in pigs. Restrictions are lifted after final veterinary and sanitary measures. When avian mycobacteria or atypical mycobacteria are isolated from pigs, reacting animals are sent for slaughter. Horses and small cattle are tested for allergies every 60 days until a negative result is obtained for the entire group of animals. Reactive animals are sent for slaughter.

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Chlamydia is a zooanthroponotic, infectious disease of animals, the causes and conditions of its occurrence, economic damage from it. Development, course and symptoms of the disease, pathological changes. Diagnosis, prevention and treatment of chlamydia.

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History of discovery and scope of distribution, economic damage caused by the plague. Pathogens of the disease, etiology, course and symptoms. Pathological changes and diagnosis of plague. Development of measures for the prevention and elimination of the disease.

Tuberculosis is an infectious, chronic disease of all species of animals and humans, characterized by the formation of specific nodules in various organs that undergo caseous necrosis and calcification.

Historical reference. Tuberculosis has been known to mankind since ancient times. Hippocrates (4th century BC) described the clinical signs of tuberculosis in humans and recommended treatment methods. The term “tuberculosis” was first used by the French physician Lenek (1819) in 1869. Villemin established the infectiousness of tuberculosis.
The causative agent of the disease was discovered by R. Koch in 1882. In 1890, he produced the diagnostic drug tuberculin.

In 1924 And Calmette and S. Guerin produced the BCG vaccine for the specific prevention of tuberculosis in humans.
Tuberculosis is registered in many countries of the world. In Russia, the prevalence of tuberculosis among animals is insignificant.
Eradication of tuberculosis is a serious problem and is especially urgent because the disease is zoonotic and anthropozoonotic.

Economic damage. Tuberculosis causes great economic damage to livestock production, which is associated with a decrease in productivity, premature culling and delivery of animals for slaughter, lengthy and expensive anti-epizootic measures and other material costs.

The causative agent of the disease-Mycobacterium tuberculosis, a rod from 0.5 to 8µ long, often bent at an angle, sometimes appears in the form of grains located in one line. The microbe is a strict aerobe, non-motile, does not form spores, acid-resistant, and also alcohol- and antimorphine-resistant. The acid-fastness of the tuberculosis bacillus is used to differentiate it from other non-acid-fast bacteria. The tuberculosis bacillus contains fatty wax and therefore does not accept paint well, but, being colored with carbolfuchsin when heated, it retains this paint better than other microorganisms. When smears are treated with a weak solution of sulfuric acid, tuberculosis bacteria are not discolored (they are stained magenta red), but other microbes are discolored (Ziehl-Neelsen method). In smears they are located singly or in groups.

There are three known types of tuberculosis bacillus: human (humanus), bovine (bovines), avian (avium), which are varieties of the same species. Under certain conditions, they can sometimes change, turning into other types. Most often there is a transition from the bull type to the human type. In 1937, Wales isolated a special type of bacteria from the field mouse, called the Oxford strain. This strain is close to the bovine type. Other scientists consider it the fourth type of tuberculosis bacillus - mouse.

The main difference between the types is their unequal virulence for individual species of animals and humans.

Mycobacterium tuberculosis (human species) causes tuberculosis in humans. TO this species Pigs, cats, dogs, cattle, and fur-bearing animals are also susceptible to mycobacteria, but birds (with the exception of parrots) are not susceptible.

Micobacterium bovis (bovine species) causes tuberculosis in all types of agricultural and wild animals, including fur-bearing animals, as well as humans. Birds are not susceptible to this type of mycobacteria.

Mycobacterium avium (avian species) causes tuberculosis in domestic and wild birds; pigs are susceptible to this type of mycobacterium; Animals of other species and humans are rarely infected.
In nature (in peat and soil) there are opportunistic atypical and saprophytic mycobacteria, which in their morphological and cultural properties are close to avian mycobacteria.

Animals infected with such mycobacteria can react to tuberculin for mammals, which is used by practical veterinarians when carrying out planned anti-epizootic measures, which causes certain difficulties when carrying out allergic diagnosis of tuberculosis.

Due to the content of fatty wax elements, the tuberculosis bacillus is very resistant to the external environment and to the effects of disinfectants. In air-dried pieces of affected lungs, microbes remain virulent for 200 days, and in soil and manure they remain viable for up to 4 years, and in birds for up to 10 years. Sunlight disinfects bacteria in sputum after only 72 hours. In products obtained from sick animals, the tuberculosis pathogen persists: in milk for up to 19 days, in butter for up to 300 days, in cheese for 145-200 days, in frozen meat for up to 1 year, in salted meat for 60 days. In the carcasses of cattle and birds, mycobacteria persist from 3 to 12 months.
Heat has a detrimental effect on tuberculosis bacteria. Heating milk to 55° kills them after 4 hours, to 85° kills them after 30 minutes; when milk is boiled, mycobacteria die after 3-5 minutes.

Chemicals have a detrimental effect on bacteria over relatively long periods of time: a 5% solution of carbolic acid - after 24 hours, a 5% formaldehyde solution - after 12 hours, a solution containing 5% active chlorine - after 3 hours.
The best disinfectants are a 3% alkaline solution of formaldehyde (exposure 1 hour), a suspension of bleach containing 5% active chlorine, a 10% solution of iodine monochloride, a 20% suspension of freshly slaked lime, a 5% solution of hypochloride calcium, 1% solution of glutaraldehyde and other drugs.

Epizootological data. More than 55 species of domestic and wild animals and about 25 species of birds are susceptible to tuberculosis. The most susceptible are cattle and pigs, fur-bearing animals are minks, and chickens are among birds. Less commonly, goats, dogs, birds, ducks and geese get sick with tuberculosis. Sheep, horses, and cats very rarely get sick.
The main source of infectious agents for tuberculosis are sick animals. They excrete bacteria in feces, sputum, milk, and when infected genitourinary tract- with sperm. In cattle with pulmonary tuberculosis, there may be up to 100,000 tuberculosis bacteria in 1 g of sputum. When coughing, part of the sputum is sprayed into the air, and part is swallowed by animals and comes out with feces. A cow with tuberculosis is capable of excreting an average of 37 million tuberculosis bacteria per day in feces. The excretions of animals sick with tuberculosis contaminate the environment: premises, walking yards, pastures, watering places.

Factors of transmission of the infectious agent can be feed, water, bedding, manure, etc.

Infection with tuberculosis occurs more often during the stall period when animals are kept in crowded conditions. Young animals become infected mainly through milk and skimmed milk obtained from sick animals. Intrauterine infection of calves is possible. Animals can become infected through contact with people with tuberculosis, especially milkmaids and calves who do not undergo annual medical examinations. On pasture, infection is less common, since bacteria die under the influence of sun rays, but if the summer is rainy and cold, then mass overinfection of animals is possible in the pasture. During the stall period, adult cattle are infected mainly by aerogenous means, while on pasture they become infected through nutritional means; pigs become infected by feeding them undisinfected kitchen waste from hospitals, tuberculosis dispensaries, or by contact with sick birds. Dogs and cats - from sick people open form tuberculosis or from eating milk and meat from sick cows.

Poor living conditions, inadequate feeding, and excessive exploitation reduce the resistance of animals to tuberculosis. Abrupt transitions from one living conditions to another, replacement of feed, lack of regular exercise in the fresh air, crowded and damp rooms and other unsanitary conditions for keeping animals also have a negative impact.

In beef cattle kept in the steppes, the incidence of tuberculosis is insignificant. However, as soon as cattle are deprived of the conditions to which they are accustomed, resistance to tuberculosis drops and the cattle get sick.

In herds, tuberculosis usually spreads slowly, with massive re-infection of livestock occurring over several months. The comparatively slow spread of tuberculosis is explained, on the one hand, by the length of the incubation period, and on the other, by the fact that not all sick animals are active bacteria excretors.

Most often, a certain number (sometimes significant) of sick animals is detected in the spring, when the veterinary service carries out routine tuberculinization on farms, but sometimes livestock is re-infected on pasture, especially if the summer is damp and cold.

Pathogenesis. Having penetrated the animal's body with inhaled air or through the digestive tract, tuberculosis bacteria enter the lungs or other organs through the lymphogenous and hematogenous routes. At the site of localization of tuberculosis bacteria, an inflammatory process develops, followed by the formation of tuberculosis nodules, tubercles the size of a lentil grain, grayish in color, and round in shape. In the center of the tubercle, dead cells are converted into a curdled mass under the influence of mycobacterial toxins.
Depending on the resistance of the organism and the virulence of the bacteria, the tuberculosis process can be benign or malignant.

In a resistant organism, tuberculosis bacteria are surrounded by epithelioid cells, from which giant cells are subsequently formed. This entire group of cells is surrounded by a ring of lymphocytes. Exudate is deposited between the cells and fibrin coagulates. The developing avascular tuberculous tubercle (granuloma) is encapsulated. Tissue cells in the tubercle die due to the lack of influx of nutrients, and under the influence of bacterial toxins, a curdled mass is formed, impregnated with lime salts. With such a benign course of the disease, in such an encapsulated focus, tuberculosis bacteria in Eventually may die and further development of the infectious process stops.

In cattle, tuberculosis of the serous membranes (pleura, peritoneum) - “pearl oyster” - is quite often observed. In this form of the disease, inflammation from the very beginning is productive. Tuberculous tubercles undergo fibrinous degeneration and turn into dense shiny growths.

In an organism with reduced resistance, the process of delimitation and localization of the tuberculosis pathogen is weakly expressed. Due to insufficient encapsulation, melting of the walls of tuberculous nodules occurs. Mycobacteria enter healthy tissue, which leads to the formation of new small (miliary) nodules. The latter merge with each other and form large tuberculous foci. If the cheesy mass is released from these foci, for example in the lungs through the bronchi, then cavities are formed. The pathogen spreads through the lymphatic vessels; When it enters the circulatory system, bacteremia occurs in the animal’s body. Bacteria are spread throughout the body, the process generalizes, and many organs are affected (liver, kidneys, spleen, etc.).

The resistance of an animal's body depends not only on its initial state, but also on the conditions in which it is located. If available on the farm favorable conditions feeding and maintenance that increase the body's resistance, the beginning development of the tuberculosis process can be delayed at a certain stage. Even large tuberculosis foci can be subject to encapsulation and calcification in the body of animals. Immuring the causative agent of tuberculosis either leads to the suppression of its reproduction, or ends in the death of the pathogen, and then the body of the sick animal recovers.

In the case of generalization of the tuberculosis process and extensive lung damage, gas exchange is disrupted, toxins of tuberculosis bacteria reduce erythropoiesis, which causes anemia. If this is accompanied by intestinal lesions, accompanied by impaired absorption of nutrients, then the animal suffers exhaustion and death.

Course and symptoms of the disease. The duration of the incubation period for tuberculosis ranges from two to six weeks. Tuberculosis in animals is chronic or latent, so clinical signs of the disease may appear several months or even years after infection.

The onset of tuberculosis in animals in private household plots, peasant farms and agricultural enterprises is determined during routine diagnostic tests for tuberculosis (tuberculinization) by veterinary specialists based on the presence of positive allergic reactions.
When animals that react positively are sent for diagnostic slaughter, and during post-mortem examination of organs and lymph nodes, signs characteristic of tuberculosis are found.

Conventionally, active, or open, tuberculosis is distinguished when tuberculosis bacteria with bronchial mucus, excreted in feces or milk, and latent tuberculosis, when the bacteria are so isolated in the tuberculosis focus that they are not excreted.

When the intestines, udder and uterus are affected, the tuberculosis process is always open; when the lungs are affected - not always, but very often. Based on the location of the pathological process, pulmonary and intestinal forms of tuberculosis are distinguished; In addition, animals also have lesions of the udder, serous integument (pearl mussel), genital form and generalized tuberculosis. The course of the disease in individual animals is generally similar, but there are some peculiarities.

In cattle Tuberculosis is mostly chronic or latent. In young animals - acute and subacute. Clinical signs of the disease are: increased body temperature (39.5-40°C), moist cough, especially in the morning. The mucus released when you cough sometimes contains pieces of dead tissue. Sick animals experience shortness of breath. Auscultation of the chest in the lung area reveals wet or dry rales. If an animal's pleura is affected by the tuberculosis process, the animal will experience pain when pressing between the ribs. A sick animal loses weight. The skin becomes dry and loses elasticity.

With generalized tuberculosis, the lymph nodes (submandibular, retropharyngeal, parotid, cervical, prescapular, inguinal, knee fold, suprauterine) become enlarged. When palpated, the affected lymph nodes are dense, sometimes lumpy, and painful. An enlargement of the mediastinal nodes leads to compression of the esophagus, and this disrupts the belching process and causes chronic swelling of the rumen.

If the udder of animals with tuberculosis is affected, then part of it, usually the back, swells, becomes painful and hard. Milk mixed with blood or curdled mass is squeezed out of the nipples.

When the intestines are affected, intermittent diarrhea is initially observed, which then becomes constant. A sick animal develops cachexia. Damage to the uterus and vagina is accompanied by abortion, nymphomania, barrenness. A glassy discharge mixed with pus is released from the vagina. Damage to the genital organs in bulls is complicated by orchitis. A pearl oyster on the pleura can be identified by auscultation.

The tuberculosis process, as a rule, progresses slowly. The disease can last for many years. Some sick animals recover, and in cases where the primary complex becomes sterile, the animal loses sensitivity to tuberculin. Most animals with tuberculosis appearance and general condition are no different from healthy ones. Tuberculosis lesions are found only at slaughter.

Horses suffer from tuberculosis relatively rarely, mainly on farms where cattle suffer from tuberculosis, and the disease most often occurs latently. If the tuberculosis process is severely expressed, severe emaciation of the animal is noted, although the appetite for a long time may persist. When the lungs are affected, a weak cough appears, and the horse quickly gets tired of working. In some cases, there have been cases of damage to the nasal mucosa with the presence of nodules and ulcers.

Young horses have tuberculosis of the intestines and mesenteric lymph nodes. In this case, we notice poor appetite and colic appears. Constipation gives way to severe diarrhea. Equine tuberculosis is characterized by polyuria, the amount of urine excreted increases 3-4 times.

Porcine tuberculosis observed in farms where there are cattle or poultry with tuberculosis. The disease in pigs is predominantly asymptomatic. The most characteristic clinical signs are enlargement of the submandibular, retropharyngeal and cervical lymph nodes. Sometimes abscesses form in these nodes, after opening which fistulas remain, from which a purulent-curdled mass is released. If the lungs are affected, coughing and vomiting, difficulty breathing are observed, and if the intestines are affected, diarrhea occurs. Sick pigs lose weight quickly.

In sheep and goats Tuberculosis basically proceeds in the same way as in cattle. More often the disease is asymptomatic. With a highly expressed tuberculosis process, patients experience coughing, nasal discharge, and emaciation. In goats, udder damage is characterized by the formation of hard, lumpy swellings, sometimes reaching a significant size.

Avian tuberculosis. Chickens get sick more often, geese and turkey ducks much less often. The disease is chronic with very unclear clinical signs. Sick chickens become lethargic and lose weight while maintaining their appetite. The crest becomes pale and wrinkled, the bird is inactive, egg production decreases, and the pectoral muscles atrophy. Generalization of the tuberculosis process is accompanied by damage intestinal tract. Vomiting and diarrhea are observed, causing severe exhaustion of the bird. Sometimes bones and joints are affected, and lameness is noted. A sick bird develops anemia: the number of red blood cells drops to 1 million, the hemoglobin content to 35%.

Canine tuberculosis. In dogs, tuberculosis is characterized by low-grade fever, decreased appetite, lethargy, and gradual emaciation of the animal. There is a cough and nasal discharge. If the intestines are affected, diarrhea occurs. Due to tuberculosis, dogs may develop synovitis and deforming osteoarthritis. Death occurs from complete exhaustion.

Camel tuberculosis. The cervical and submandibular lymph nodes are affected; There is a cough, increased sweating, and rapid fatigue.

From fur-bearing animals Silver-black foxes, minks and nutria are susceptible to tuberculosis. Young animals get sick more often. The disease is predominantly chronic; weakness, lethargy, and progressive emaciation are noted. When the lungs are affected, coughing, difficulty and rapid breathing are observed. If the intestines are affected, diarrhea and, less commonly, constipation appear. Liver damage may be accompanied by jaundice. Foxes sometimes develop non-healing ulcers on the skin of their necks.

Pathological changes. In large and small cattle, tuberculosis most often affects the lungs and bronchial-mediastinal lymph nodes.

According to P.I. Kokurichev (1950), in cattle with tuberculosis, the lymph nodes of the chest cavity are affected in 100% of cases, the lungs in 99% of cases; other organs - rarely: liver - 8%, spleen - 5%, udder - 3%, intestines - 1%.

When opening the lungs, dense foci of reddish-gray or yellowish color. The contents of the lesions are cheesy or calcareous. Sometimes the lesions look like purulent foci surrounded by a thin connective tissue capsule. Around such foci are scattered nodules of various sizes, from a pinhead to a millet grain. The presence of cavities surrounded by a dense capsule is also characteristic. Tuberculous foci can be detected, although much less frequently, also in other parenchymal organs, in bone marrow and bones. The pleura is also affected, and sometimes fusion of its leaves is observed. The so-called pearl mussel is characterized by the formation of small tuberculous nodules on the serous membranes of the chest and abdominal cavities with the simultaneous proliferation of connective tissue. A cluster of dense nodes looks like cauliflower. On a section of the lymph nodes affected by tuberculosis, a curdled degeneration is detected. On the mucous membrane of the pharynx, small intestine and cecum, individual tubercles and ulcers of various sizes are observed, having a hard bottom, they are covered with a dry cheesy mass.

When autopsying the corpses of adult horses that died from tuberculosis, changes are found mainly in the lungs, often in the form of a miliary process. In foals, damage to the mesenteric lymph nodes is noted. The latter are enlarged, and numerous cheesy-purulent foci are found in them. Nodes and ulcers are found on the intestinal mucosa. If the liver and spleen are affected by the tuberculosis process, they can be enlarged several times. In horses, damage to the serous membranes (pearl oyster) is also observed.

When autopsying birds that have died from tuberculosis, specific lesions are often found in the liver and spleen in chickens, and in the lungs in geese and ducks.
The liver and spleen are usually sharply enlarged, have a flabby consistency and contain numerous tubercles located both in the depths and along the periphery of the organ. Tuberculosis focuses different sizes are sometimes found in large quantities in the small and large intestines, where they are located in the mucous membrane and submucosal layer. There may be ulcers of various sizes on the mucous membrane. The lymph nodes of the mesentery are enlarged and contain caseous masses. In rare cases, tuberculosis lesions are found in the kidneys and bones.

Diagnosis Tuberculosis is diagnosed comprehensively, taking into account epizootic data, clinical signs and the results of allergic, pathological, histological, bacteriological and biological studies.

The clinical diagnostic method is of limited value, since in large animal species this method can be used to identify very few patients with tuberculosis.

The main method of intravital diagnosis of tuberculosis is allergic. Allows you to identify patients with any form of tuberculosis, regardless of whether the animal has clinical signs of the disease or not.

To diagnose tuberculosis in cattle, buffaloes, pigs, goats, sheep, horses, camels, dogs, monkeys and fur-bearing animals, tuberculin is used - a sterile filtrate of killed cultures of the tuberculosis pathogen of two types: dry purified (PPD) tuberculin for mammals and PPD - tuberculin for birds. Tuberculin PPD for birds is prepared from the causative agent of avian tuberculosis and is used for the diagnosis of tuberculosis in birds and pigs.

The main intravital method for diagnosing tuberculosis in animals is an allergic intradermal tuberculin test. In horses, camels, and buffaloes, diagnosis is carried out using the eye method (ophthalmic test). If necessary, an ophthalmic test is also carried out in cattle simultaneously with an intradermal test.

Tuberculinization is subjected to:

• cattle (buffaloes) twice a year: in the spring, before pasture, and in the fall, before putting the cattle into winter housing, and young cattle from 2 months of age, cattle of fattening groups - once a year;
• horses, mules, donkeys, sheep and goats - depending on the epizootic situation;
• all adult sows, as well as young animals after weaning in all breeding farms - once a year, and on other pig farms - depending on the epizootic situation;
• adult birds (over two years old) of original lines and ancestral flocks at breeding factories and breeding poultry stations - once a year.

Animals belonging to citizens living on the territory of farms or in individual settlements are examined for tuberculosis simultaneously with tuberculinization on the farm.

With the intradermal method of tuberculinization, tuberculin is injected into the middle of the neck of cattle, buffalo, zebu, deer (deer) in the middle of the neck, in bulls - under the tail fold, in camels - in the area of ​​the outer surface of the ear 2 cm from its base, in goats - in the thickness lower eyelid; for dogs, monkeys and fur-bearing animals (except minks) - in the area of ​​the inner thigh or elbow fold; minkam - intrapalpebrally into the upper eyelid; for cats - in the area of ​​the inner surface of the ear; for chickens - in the beard; for turkeys - in the submandibular earring; for geese, ducks - in the submandibular fold; for male pheasants - in the cavernous bodies of the head; peacocks, parrots, pigeons, cranes, herons, storks, flamingos - in the area of ​​the outer side of the lower leg 1...2 cm above the ankle joint.

Before tuberculin is administered, the fur (hair) at the injection site is trimmed (feathers are plucked), and the skin is treated with 70% ethyl alcohol.

Reading of the reaction to intradermal injection of tuberculin is carried out in cattle, buffaloes, zebu cattle, camels and deer in 72 hours; in goats, sheep, pigs, dogs, cats, monkeys, fur-bearing animals in 48 hours; in a bird in 30-36 hours. In areas unaffected by tuberculosis, cattle and camels are allowed to re-inject tuberculin 72 hours after the first injection in the same dose and in the same place. The response to repeated administration is recorded and assessed after 24 hours.

When taking into account the intradermal reaction, the site of tuberculin injection is palpated in each animal under study; in minks, the eyelids of the left and right eyes are visually compared.

If, during reading, thickening of the skin is detected at the site of tuberculin injection in cattle, buffalos, zebu cattle, camels, deer, we take a cutimeter and measure the thickness of the fold in millimeters and determine the magnitude of its thickening, comparing it with the thickness of the fold of unchanged skin near the site of tuberculin injection.

Animals are considered tuberculin responsive:

• cattle (except bulls), buffalo, zebu, camels, deer, deer, antelope - with thickening of the skin fold by 3mm or more regardless of the nature of the swelling (swelling, pain, increased local temperature);
• bulls, sheep, goats, elephants, rhinoceroses, hippopotamuses, pigs, dogs, wolves and other representatives of carnivores, birds, dolphins, cats - when swelling forms at the site of tuberculin injection.

Intradermal tuberculin test - a highly specific reaction to tuberculosis. At the same time, it depends on the general immunoreactivity of the body. In old, deep-pregnant animals, in animals with low fatness, as well as in generalized tuberculosis, the reaction to tuberculosis may be weakly expressed or absent altogether (anergy).

Veterinary specialists conducting tuberculinization should keep in mind that sometimes nonspecific (para- and pseudo-allergic) reactions to tuberculin for mammals are possible, due to sensitization of the body by avian mycobacteria, pathogens of paratuberculosis and atypical mycobacteria, as well as other reasons. To differentiate nonspecific reactions, a simultaneous allergy test is used, which is carried out simultaneously with tuberculin for mammals and a complex allergen from atypical bacteria (CAM). If, when reading the reaction, the intradermal reaction to the administration of CAM is more intense than to tuberculin for mammals, veterinary specialists consider the reaction to be nonspecific; material from such animals is examined for tuberculosis using laboratory methods.
Tuberculinization by the eye method (ophthalmic test) is used to diagnose tuberculosis in horses and other representatives of equids.

In cattle, this method can only be used simultaneously with an intradermal tuberculin test for additional identification of infected animals in farms unaffected by tuberculosis or when selecting animals for diagnostic slaughter. The diagnosis of tuberculosis during pathological examination is most often confirmed in animals that react simultaneously when examined in each of the samples.

Ocular tuberculinization is carried out twice with an interval of 5-6 days between administrations. Tuberculin in an amount of 3-5 drops is applied with a pipette or syringe without a needle to the conjunctiva of the lower eyelid or to the surface of the cornea with the lower eyelid retracted.

Animals that responded to the first injection of tuberculin are not given the drug again.

The results of the ophthalmic test are recorded after 6,9,12, and 24 hours after the first and 3,6,9 and 12 hours after repeated administration of tuberculin. Positive reaction characterized by the formation of mucopurulent or purulent secretion accumulating in the conjunctival sac or flowing in the form of a cord from the inner corner of the eye, hyperemia and swelling of the conjunctiva. When taking into account the reaction, it is necessary to retract the lower eyelid and inspect the conjunctival sac, since the reaction may be limited to the short-term formation of purulent secretion in the form of grains.

Short-term hyperemia and lacrimation with the formation of a small amount of mucous secretion, as well as the absence of any changes, are assessed as a negative reaction.

If, during routine tuberculinization in a prosperous farm, animals that react to tuberculin are identified for the first time, then in order to clarify the diagnosis, under the supervision of specialists from the state veterinary network, a commission diagnostic slaughter of 3-5 animals with the most pronounced reactions to tuberculin is carried out and the internal organs and lymph nodes are examined. If pathological changes typical of tuberculosis are detected in at least one of the killed animals, the diagnosis is considered established.

If changes in organs and tissues characteristic of tuberculosis are not found in killed animals, material is taken for bacteriological examination with a bioassay. When mycobacterium tuberculosis of bovine or human species is isolated from material from killed animals or with a positive bioassay, the diagnosis is also considered established;

Immunity and specific prevention.

The emergence and development of the tuberculosis process is accompanied by irritation of the central nervous system. This causes an increase in the body's specific sensitivity to tuberculosis bacteria and their toxins. Increased sensitivity, or allergy, is detected several days or weeks after bacteria enter the body and marks not only the emergence of an infectious process, but also the beginning of the formation of a certain degree of non-sterile immunity.
In tuberculosis, phagocytosis is rarely complete; bacteria multiply in neutrophils and macrophages. Agglutinins, precipitins and complement-fixing antibodies also play a minor role in immunity. In the process of evolution, the body has developed the ability to isolate (immine) the pathogen in granulomas-tubercules. The degree of this ability, depending on many factors, including the virulence of the pathogen, can be different, and this determines the outcome of the disease. Infectious (non-sterile immunity) continues as long as tuberculosis bacteria are in the body; with their release or death, immunity also ceases.

For specific prevention of tuberculosis in medical practice, the BCG vaccine, made by Calmette and Guerin (1924) from a culture of bovine mycobacteria, is widely used.

Specific prevention of tuberculosis with the BCG vaccine is possible, but in most countries farm animals are not vaccinated against tuberculosis.

Prevention. Prevention and control measures against tuberculosis are carried out in accordance with current sanitary (SP 3.1 093-96) and veterinary rules (VP ​​13.3 1325-96).

Animal owners, farm managers, regardless of their form of ownership, peasant farm owners and others are obliged to:

• if you have or purchase animals, register them at a veterinary institution, obtain a registration number in the form of a tag and monitor its safety;
• purchase, sale, slaughter, pasture, placement on pastures and all other movements and regroupings of animals, sale of livestock products must be carried out only with the knowledge and permission of the state veterinary service authorities;
• equip the necessary veterinary and sanitary facilities;
• take precautions when preparing feed to prevent infection;
• quarantine newly arrived animals for 30 days for veterinary research and treatment;
• promptly inform the veterinary service about all cases of illness in animals with suspected tuberculosis (loss of fatness, signs of pneumonia, enlarged superficial lymph nodes);
• provide, at the request of veterinary specialists, all necessary information about purchased animals and create conditions for their examination, research and treatment;
• comply with zoohygienic and veterinary requirements when transporting, keeping and feeding animals, and constructing livestock facilities;
• carry out timely delivery of sick animals or complete elimination of all unfavorable livestock as directed by veterinary specialists;
• ensure the implementation of restrictive, organizational, economic, special and sanitary measures provided for in these rules to prevent tuberculosis in animals, as well as to eliminate an epizootic outbreak in the event of its occurrence, with the allocation of the necessary material, technical and financial resources.

Treatment. Animals with tuberculosis are sent for slaughter. In herds, on farms, in populated areas where the disease has already been established, animals that react to tuberculin are recognized as having tuberculosis and sent for slaughter within 2 weeks.

Content:

Tuberculosis is a highly contagious, chronic bacterial disease that affects all types of warm-blooded animals, wild birds, and poultry. Belongs to the group of anthropozoonoses. Poses danger to humans. The disease is characterized by the formation of specific nodules (tubercles) on the skin and in various internal organs, which undergo caseous necrosis and calcification. Everyone gets tuberculosis age groups agricultural and domestic animals. The disease causes great economic damage to farms. Treatment has not been developed, so all efforts in the fight against tuberculosis must be directed towards prevention.

Description of the pathogen

Mycobacteria that cause tuberculosis have the form of oblong, motionless rods bent at an angle, the length of which ranges from 0.5 to 8 nm. In smears they are located in separate small groups.

Mycobacteria are acid-alcohol-resistant strict anaerobes, that is, their development occurs without access to oxygen. They do not form spores or capsules. They do not have cilia, flagella, or other devices for movement.

The infectious disease in animals is caused by several serotypes of bacteria. The genus Mycobacteria includes more than 30 different species of pathogenic and non-pathogenic microorganisms. In terms of morphology and cultural properties, pathogenic mycobacteria of all types are largely similar to each other.

Important! IN natural environment In addition to tuberculosis, there are also opportunistic atypical, saprophytic mycobacteria. Animals infected with them can react to mammalian tuberculin, which causes certain difficulties in making a diagnosis, namely in the allergic diagnosis of tuberculosis.

The species of tuberculosis is determined by the peculiarity of their growth on nutrient culture media, as well as by the degree of pathogenicity of individual types of pathogen on laboratory animals of various species.

Tuberculosis affects all types of domestic, wild, and farm animals, regardless of breed or age. The disease is of a natural focal nature. Mycobacteria affect cats, dogs, cattle, rabbits, sheep, goats, fur-bearing animals, poultry, and rodents. Wild birds are less susceptible to this infection.

Thus, bovine tuberculosis is provoked by the bovine species (M. bovis). The bacterium, having penetrated the cow’s body, causes the development of serious systemic and functional disorders.

It is also worth noting that large horned agricultural animals (cattle) become ill when tuberculin bacilli enter their bodies human type(Mycobacterium tuberculosis). In this case, the infection occurs with less pronounced clinical symptoms.

The morphological and functional characteristics of both species are identical. The bacteria are anaerobic, form small chains, and are less often presented in the form of individual individuals. Frozen meat lasts for more than a year.

How do animals get infected?

Domestic, wild, and farm animals can become infected with tuberculosis through direct contact with infected individuals that are latent bacteria carriers.

Mycobacteria remain in the body for a long period of time in the form of £-forms. At the same time, infected individuals often remain an undetected source of the tuberculosis pathogen. Under unfavorable conditions, £-forms of mycobacteria can revert to the classical form. Therefore, virus carriers in whom the disease manifests itself up to a certain point without obvious clinical symptoms, become a potential cause of tuberculosis.

The main factors for the transmission of mycobacteria are:

• infected feed, drinking water;
• pastures, litter, manure;
• household items, equipment, clothing of farm workers.

Infection of young cattle mainly occurs through milk, dairy products, reverse, which were obtained from individuals infected with tuberculin bacilli.

The causative agent of tuberculosis enters the body mainly through damaged mucous membranes of the respiratory tract, as well as through the digestive tract. Tuberculosis in cattle is transmitted by aerogenic, nutritional routes. Transplacental (intrauterine) infection is possible. Small calves can become infected with mycobacteria through colostrum and mother's milk.

The risk group includes:

Tuberculosis can affect agricultural animals that receive an unbalanced diet, low-quality feed, or meat products of dubious origin that have not undergone preliminary testing. heat treatment.

The risk of infection increases if cattle and other types of warm-blooded animals are kept in unfavorable conditions in crowded group housing. Lack of properly equipped walking areas, normal temperature regime, ventilation, cold, dampness, high humidity in the premises, and other mistakes made when keeping agricultural and domestic animals can also cause infection.

Individuals infected with mycobacteria (sick, latent virus carriers) release the causative agent of tuberculosis with urine, milk, sputum, feces, and sperm into the external environment.

Outbreaks of the disease are recorded regardless of the time of year. At the same time, animals most often suffer from tuberculosis in the spring and summer.

The infectious process of tuberculosis develops slowly - over months or even years. Infection with the causative agent of tuberculosis and the spread of the disease are facilitated by: inadequate feeding, crowded keeping of animals, dampness, cold, drafts in the room, unsanitary conditions of keeping animals.

Pathogenesis

After entering the body of infected animals, mycobacteria are carried through the bloodstream and lymphogenous route to various internal organs and systems. Not only the lungs are affected, but also the liver, spleen, kidneys, and regional lymph nodes.

In this case, the greatest localization of tuberculin bacilli is noted in the lungs. Acute inflammation develops in the places where they are located. Destructive and degenerative processes occur in tissues. When autopsying animal corpses, extensive lesions and necrotic areas are visible in the lungs.

Tuberculosis is characterized by the formation of specific tubercle nodules in the tissues of organs. They have a dense consistency, round shape, and light gray color. In size they can be compared to lentil grains. In the center of the tubercle, dead cellular structures are converted into a curdled mass under the influence of mycobacterial endotoxins.

Tuberculosis occurs predominantly chronically in adult animals, and acutely or subacutely in young animals. Moreover, the duration of the incubation period depends on the body’s resistance, immune potential, and individual physiological characteristics. From the moment of infection until the first clinical symptoms appear, it can take from several days to 5–6 weeks.

In some cases, the first manifestations of tuberculosis in animals are observed 3–5 months after infection. Depending on the resistance, persistence of the organism and the virulence of the bacteria, the tuberculosis process in a cow or goat can be benign or malignant.

In a benign course of infection, tuberculosis bacteria are gradually surrounded by epithelioid cells, from which giant cell structures are subsequently formed. This entire group of cells is surrounded by a ring of lymphocytes. Exudate is deposited between them and fibrin coagulates. The developing tuberculous granuloma is encapsulated.

Tissue cells in the tubercle gradually die due to lack of nutrient supply. As the disease progresses, under the influence of endotoxins produced by mycobacteria, a curdled mass impregnated with lime salts is formed. In a benign course of the disease in an encapsulated lesion, tuberculosis bacteria most often die, and the further development of the infectious process stops.

Forms of tuberculosis and clinical symptoms

If an animal suffers from tuberculosis, the symptoms depend on the primary site of entry of the bacteria and the location of the pathogen. Based on the location of the pathological process, pulmonary and intestinal forms of bacterial disease are distinguished. Less commonly, large and small cattle are diagnosed with lesions of the udder, serous integument (pearly mussel), genital form or generalized tuberculosis. Very often this disease in cows occurs latently.

In cattle, tuberculosis most often affects the lungs. This form of the disease is characterized by a strong dry cough, which intensifies when inhaling cold air. On initial stage the temperature may be normal or rise to 39.5–40 °C. Appetite and productivity are preserved.

As the infection progresses, signs of inflammation of the lungs and pleura appear in tuberculosis. The cough becomes painful, breathing is shallow, rapid, difficult, accompanied by wheezing and groaning. Sputum is produced. In this case, coughing attacks intensify in the morning or at night. During percussion, wheezing and areas of dullness can be clearly heard in the chest.

If the lungs or pleura are affected by the tuberculosis process, upon palpation or pressure between the ribs the animal will experience severe pain. Infected individuals quickly lose weight and appear emaciated. The skin becomes dry and loses elasticity. If the mediastinal lymph nodes become enlarged, this will invariably lead to compression of the esophagus. The belching process is disrupted, and chronic swelling of the rumen occurs.

Important! With generalized tuberculosis and extensive lesions of the lungs, infected animals die due to severe intoxication, dysfunction of the respiratory center, and severe exhaustion.

In case of damage to the mammary gland, an increase in the suprauterine lymph nodes is noted, which acquire a dense consistency, become lumpy, and inactive. The back of the udder is most often affected. The mammary gland turns red, swells, and becomes painful. When milking, a curd mass, watery milk, which contains bloody clots, inclusions, threads, and fibrin clots, is released from the milk bags.

When the genital organs are damaged in cows, increased sexual heat, barrenness, mucus, and a foul-smelling green thick mass are secreted. Orchitis and uveitis are observed in bulls.

With a generalized form of infection, the mandibular, retropharyngeal, and suprauterine lymph nodes become painful and increase in size.

Diagnosis of tuberculosis

As a rule, the onset of the disease can be detected in agricultural animals (cows, goats, pigs) during a routine examination, in the process of diagnostic studies. The diagnosis of suspected tuberculosis is made on the basis of epidemiological information for the region. Anamnesis data and clinical manifestations are taken into account.

For the study, an allergen is used - tuberculin, which is a sterile filtrate of killed cultures of the causative agent of tuberculosis of two types: dry purified (PPD) tuberculin for mammals and PPD tuberculin for birds.

The main method of intravital diagnosis of tuberculosis in animals is an allergic study with an intradermal tuberculin test. Cattle are subjected to tuberculinization starting from two months of age. In some cases, in cattle, simultaneously with an intradermal test, an ophthalmic test is performed with an interval of 5–6 days.

With the intradermal method of tuberculinization, the drug is injected into the middle of the neck of cows, and into the sub-tail fold of bulls. Before administering tuberculin, the hair at the injection site is cut off, and the skin is treated with 70% ethyl alcohol.

If thickening of the skin is detected at the site of allergen injection in cattle, the thickness of the fold in mm is measured using a cutimeter. The magnitude of its thickening is determined by comparing it with the thickness of the fold of unchanged skin near the site of injection of a specific allergen.

Animals are considered responsive to tuberculin if the skin fold thickens by 3 mm or more after the first administration of tuberculin, and by 4 mm after repeated administration.

Given the similarity of clinical symptoms, if tuberculosis is suspected, differential diagnosis is carried out.

If animals reacting to tuberculin were first identified in prosperous farms, to clarify the diagnosis, 3–5 animals with the most pronounced reactions to tuberculin are slaughtered. After slaughter, internal organs and lymph nodes are examined. If there are no changes typical for tuberculosis, pieces of organs and tissues are selected. The material is sent to the veterinary laboratory for bacteriological research.

In the affected organs, specific compactions, nodules (tubercles) are noticeable, and there are necrotic areas. Lymph nodes are enlarged and have a lumpy consistency. Pathological processes are noted in the lungs, liver, spleen, and other internal organs.

Treatment, prevention

Treatment of animals diagnosed with any form of tuberculosis is not provided. Sick individuals are sent for slaughter. Corpses are disposed of in accordance with established sanitary and hygienic standards. In herds, on farms, in populated areas where the fact of the disease has already been registered, animals that react to tuberculin are recognized as having tuberculosis and sent for slaughter within two weeks.

Cattle are subjected to tuberculinization twice a year. Poultry, fur-bearing animals - once every 12 months. Horses, goats - depending on the epizootological situation in the regions.

Important! Veterinarians determine the degree of disadvantage in cattle herds taking into account the prevalence of bacterial disease. Limited - when a double tuberculin test detects up to 15% of sick animals from the livestock in a herd or on a farm. Significant degree - if more than 15–17% of infected individuals are identified.

If less than 15% of the herd has tuberculosis, recovery can be carried out by systematic research and slaughter of sick individuals. All animals, starting from 2 months of age, are examined every 45–55 days with a double intradermal tuberculin test.

At the same time, animals of other species (including dogs and cats) on the farm are subjected to research. Individuals that react to tuberculin are considered sick. They are marked, isolated and sent to slaughter within two weeks.

In case of significant population coverage (over 15% of the herd), cows are completely replaced. All sick animals are killed and subsequently disposed of. Dairy products are subject to mandatory disinfection by heating for half an hour at 85 degrees. It is prohibited to breed cows. There is a complete ban on artificial and natural insemination. Over the next 6–7 months, the remaining animals need to be sent to slaughter.

If during a control study animals that react to tuberculin are isolated, they are all subjected to diagnostic slaughter. If pathological changes characteristic of tuberculosis are detected, further research carried out every 33–46 days.

Upon receipt of negative results from allergic, serological, and laboratory tests, the herd is declared tuberculosis-free and restrictions are lifted. Before lifting quarantine, a set of veterinary and sanitary measures are carried out.

Prevention and control measures against tuberculosis on farms and large livestock farms are carried out in accordance with current sanitary and veterinary rules (SP 3.1 093-96 and VP 13.3 1325-96). Instructions for preventive measures provide veterinary clinics, centers of the region.

To prevent infection, it is necessary to comply with sanitary and hygienic standards and monitor the epizootological situation in the region.