Topic: Anaerobic dysentery of lambs. Course and clinical manifestation

Anaerobic dysentery lambs (Dysenteria anaerobica agnorum) is an acute toxic-infectious disease of lambs in the first days of life, accompanied by general toxemia, diarrhea, rapid dehydration, acute catarrhal-hemorrhagic and hemorrhagic-ulcerative enteritis and rapid death of animals.

Historical reference. In Russia, mass diseases of lambs with diarrhea, observed in large sheep farms, were first described at the end of the last century under the name “widespread diarrhea of ​​lambs.” So, P.N. Kuleshov, P. Nikolsky and Berezov described dysentery in lambs as bloody diarrhea in 1885. The disease they described was repeated annually for a number of years during the mass lambing period, when out of 100 lambs born daily during the mass lambing period, about 70 fell ill with diarrhea; from 30 to 50 of them died. Delling and Geiger (1922), when studying the etiology, isolated the pathogen and gave the name of the disease. Lamb dysentery is widespread, mostly in areas where fine-wool sheep are raised, and causes economic damage due to the death of lambs.

Etiology. Pathogen – Cl. Perfringens type B is a stationary short, thick stick with chopped or slightly rounded ends, 4-6µ long and 1.5µ wide. In smears, the rods are usually arranged singly, in pairs, and sometimes in the form of a chain. Cl perfringens stains well with all aniline dyes, and in smears from young cultures it stains positively according to Gram, and from old cultures - weakly or negatively.

Like all capsular microorganisms, Cl. Perfringes forms a capsule in the body of animals. The microorganism belongs to the spore-forming microbes. The spores are located in the center of the stick or near its end. The spores are oval in shape, their diameter is slightly wider than the diameter of the rod.

Spore forms of the microbe in the soil will remain viable for up to 4 years and can withstand boiling for 5-9 minutes. At a temperature of 90°C -30 minutes. It persists in manure for 3-5 days. Creolin 5% kills the microbe in less than 3 minutes, milk of lime (10-20%), 1-2% sodium hydroxide solution and 3% Lysol destroy the pathogen within one minute, 2-3% carbolic acid and 96° alcohol - for 3 minutes.

Epizootological data. Since dysentery affects lambs in the first days of their life, the disease appears during the period of mass lambing, which in sheep farms usually coincides with the beginning of spring.

Dysentery in lambs usually begins with isolated cases; gradually the number of patients increases, reaching a maximum by the 10th or 15th day from the time the first cases of the disease appeared. A study of the dynamics of the disease shows that dysentery in most cases affects lambs aged 1-5 days. Disease in lambs older than 6 day-old occurs much less frequently.

Repeating annually dysfunctional farms, dysentery in lambs can cause isolated or widespread diseases in different years.

The source of infection is:

• Sick animals that excrete the pathogen in their feces.
• Healthy adult sheep are carriers of the bacilli, in whose intestines the pathogen multiplies and is periodically released into the external environment with feces, contaminating the sheepfold area, bedding, equipment and all objects that newborn lambs come into contact with.

Disputes may long time persist in the soil, which determines the stationary (enzootic) nature of anaerobic dysentery. The disease is not contagious.

Infection of lambs occurs through the nutritional route when:

• sucking on the udder of lactating sheep, contaminated with infected manure and excrement;
• when licking infected objects in the shed (feeder, bedding, equipment, etc.);
• The greatest danger is posed by the corpses of dead lambs not being collected in time and the places where they lay not being disinfected.

Causes of anaerobic dysentery in lambs:

• incomplete vaccination coverage of the entire population of ewes;
• decreased activity in the formation of colostral immunity due to low fatness of matronly ewes.

Depending on the factors contributing to the occurrence of the disease, in some sheep farms the disease is registered annually, in others it may not occur for a number of years.

Massive disease of lambs with anaerobic dysentery is mainly caused by factors that weaken the body's resistance. The most important of them is improper feeding and temperature violations.

Irrational and insufficient feeding of ewes during pregnancy is often the cause of congenital weakness of newborns. This suggests that during the period of fetal formation, the ewe’s body must be provided with the necessary amount of proteins, carbohydrates, fats, minerals and vitamins, on which the stability of a newborn lamb depends.

Cooling newborn lambs is one of the the most important conditions, contributing to the occurrence of dysentery in lambs. Cooling of the body causes a number of pathological changes in the blood, vascular endothelium and in various organs and fabrics. As a result of destruction shaped elements blood and its coagulation, blockage of small vessels occurs, which entails a deterioration in the blood supply to one or another part of the organ. This creates favorable soil for the proliferation of invading microbes in the affected areas that cause the disease.

When cooling, interstitial metabolism is sharply disrupted, immunobiological protective devices body.

Factors contributing to the occurrence of the disease include unsatisfactory conditions for keeping lambs and crowded sheds.

In dysfunctional farms, the incidence of anaerobic dysentery in lambs varies from year to year - from isolated cases to 14-29% of lambs from a dysfunctional flock; mortality can reach 100%.

Pathogenesis. The disease develops as a type of intestinal intoxication. The pathogen enters the body of newborn lambs through the mother's contaminated nipples. Once in the intestines, the pathogen begins to multiply, releasing a specific toxin (mainly β-toxin), which leads to necrotic changes in the mucous membrane, including the formation of ulcers, and is absorbed in large quantities into the blood, affecting almost all organs. Absorbed through the damaged intestinal wall, toxins and products of necrotic decay of the mucous membrane poison the lamb’s body, causing acute toxicosis syndrome. Dystrophic processes and circulatory disorders in parenchymal organs are also a consequence of toxicosis.

Clinical signs. Dysentery affects lambs in most cases in the first 3 days after birth. Less common cases of disease are observed in lambs on the 5-6th day. Incubation period does not exceed 5-6 hours.

The course of the disease can be hyperacute, acute, subacute and occasionally chronic.

In case of hyperacute flow lambs die suddenly, without sufficiently pronounced clinical signs diseases. At the same time, sick lambs show signs of damage nervous system– convulsions, loss of coordination of movements. In some sick lambs, shortly before death, the feces become liquid and bloody.

In the acute course of the disease in sick lambs, we note a depressed illness, diarrhea, feces mixed with blood and gas bubbles appear. The feces subsequently become thick, dark and mixed with mucus. Such a sick lamb stands bent over, with disheveled hair, a retracted belly and weakly reacts to its surroundings. The fur around the anus and on the tail is stained with feces and stuck together. Sometimes at the beginning of the disease there is an increase in body temperature to 40-43°C. The lambs' breathing and pulse are increased. The disease lasts from several hours to 1-3 days.

In subacute course In anaerobic dysentery, the disease takes on a protracted nature with less pronounced symptoms. In some lambs the disease can last up to 3 weeks. At clinical examination such a lamb, we note that the sick lamb lies in a state of prostration, due to diarrhea - exhausted. The stool is initially liquid, yellow or green, but later becomes thicker, black, mixed with blood, gas bubbles and mucus. Sick lambs strain, the spine is arched, the stomach is retracted, the wool is tousled. Sick lambs are depressed, refuse to suckle milk, and often go to bed. The lambs' breathing and pulse are increased. Body temperature at the onset of illness in some lambs can rise to 42°C. Subsequently, we note exhaustion and death in such lambs.

IN in rare cases the disease can take chronic course.

In some lambs, a chronic course of the disease is sometimes observed, in which the lambs recover slowly, lagging behind in growth and development. Subsequently, death sometimes occurs from complications due to intestinal ulcerations.

Pathological changes. The fatness of the corpse is below average. Hairline in the area of ​​​​the buttocks and tail is stained with liquid feces. Visible mucous membranes are anemic. Superficial The lymph nodes slightly swollen. In the abdominal, thoracic and pericardial cavities there is an accumulation of a small amount of light serous, sometimes reddish, transudate.

The most striking changes are found in the small intestine. Serosa diffusely or focally reddened, in places covered with easily removable grayish-yellowish films of fibrin. Mucous membrane small intestine, especially ileum, along the entire length or its individual segments, swollen, edematous, reddened, and in places ulcerated. The edges of the ulcers are fringed. The bottom is bright or dark red. The mesenteric and portal lymph nodes are sharply enlarged, juicy on section, dark red in color, riddled with hemorrhages (a picture of acute serous-hemorrhagic lymphadenitis). The mesenteric tissue is infiltrated with serous exudate.

The spleen is without visible changes, sometimes slight swelling is noted. The liver has a flabby consistency, is slightly enlarged, unevenly colored: areas of dark red alternate with areas of light gray or grayish yellowish color, against which small hemorrhages are clearly visible (acute congestive hyperemia, granular and fatty degeneration). In the kidneys there are phenomena of congestive hyperemia, granular and, less commonly, fatty degeneration. The heart is somewhat enlarged due to the right part, the cardiac muscle is flabby, gray-red in color, sometimes with a yellowish tint. The lungs are swollen, in a state of acute congestive hyperemia.

Diagnosis for anaerobic dysentery is based on the analysis of epizootic, clinical data, pathological changes, the presence of hemorrhagic enteritis in dead lambs or necrotic ulcers on the intestinal wall and results laboratory research. A fresh corpse (no later than 3 hours after death) or fresh sections of the affected intestine with contents, blood from the heart and pieces of parenchymal organs are sent to the laboratory.

Differential diagnosis. Anaerobic dysentery of lambs must be differentiated from, and.

Lambs aged 1-5 days are affected by colibacillosis; sometimes older lambs are affected. Necrotic inflammation and ulcers of the mucous membrane are absent, the spleen is enlarged in size. During bacteriological examination, E. coli is isolated.

Older lambs suffer from salmonellosis. Upon autopsy, we note inflammation of the mucous membrane and small intestines, but do not find ulcers characteristic of dysentery. The spleen is greatly enlarged in size. In some cases, salmonellosis is accompanied by lung damage. With bacteriological examination, it is possible to isolate a paratyphoid culture from parenchymal organs and from the blood of the heart.

Coccidiosis, unlike dysentery, mainly affects older young animals. The incubation period for coccidiosis can be longer - from 6 days to 3 weeks. Main sign coccidiosis - profuse diarrhea. The stool is often mixed with blood. When autopsying animals that have died from coccidiosis, lesions are found mainly in the large intestine. A characteristic symptom of coccidiosis is thickening of the intestinal wall. It is always possible to detect in the intestinal contents a large number of coccidia.

Immunity. With anaerobic dysentery, as with other clostridioses, antitoxic immunity is formed - recovered animals acquire stable immunity to re-infection. Lambs obtained from vaccinated ewes develop colostral immunity, which lasts up to 2 months.

Prevention. For pregnant ewes, especially in the last third of pregnancy, when the most intensive growth of the fetus occurs, animal owners must provide complete feeding. In the shed premises, strictly observe veterinary and sanitary parameters, avoiding dampness, drafts and dirt. In many sheep-raising areas, mass lambing often occurs during the period of unstable spring weather, when the cold and snowfalls have not yet stopped. Newly born lambs (especially merino lambs) will be very sensitive to low temperatures and are easily susceptible to colds and other diseases, leading to significant losses of young animals.

Hence the need arises to prepare appropriate premises for pregnant sheep and young animals. Premises for winter housing of sheep and lambing must be insulated. In the absence of insulated sheepfolds, it is necessary to have a special room - a warming house, where the queens with their offspring are transferred for the first time after lambing. Before placing sheep in stalls, the premises should be thoroughly cleaned and disinfected. Lambed sheep and newborn lambs should be housed separately in small groups, avoiding overcrowding.

Sheepfolds must have sufficient light area and be equipped with ventilation. For the winter period, the sheepfold must have the necessary supply of bedding used for pregnant and suckling queens. 2-3 weeks before the start of lambing, the sheepfolds should be cleared of manure and thoroughly disinfected.

Each sheepfold must be equipped with bases, mangers for roughage, grates, watering troughs, shields, etc., which must be kept clean.

For specific prevention Ewe lambs are vaccinated before lambing. For this purpose, a polyvalent concentrated aluminum hydroxide vaccine or a polyvalent toxoid against sheep clostridiosis is used.

For passive immunization, antitoxic serum is used against anaerobic dysentery of lambs and infectious enterotoxemia of sheep.

Treatment. Treatment of anaerobic dysentery is effective only at the onset of the disease. When dysentery appears, sick lambs along with ewes are isolated and treated with antitoxic serum against anaerobic dysentery of lambs and infectious enterotoxemia of sheep. The serum can be used together with tetracycline antibiotics.

Control measures. In permanently unaffected farms with anaerobic dysentery, all sheep are subject to vaccination, starting from 3 months of age, in accordance with the instructions for the use of the vaccine or polyanatoxin. In farms affected by dysentery of lambs and malignant edema of sheep, preventive vaccination of pregnant queens is carried out 1-3 months before the start of lambing. Upon reaching 6 months of age, lambs are revaccinated twice in doses prescribed for adult sheep. Forced vaccination in the event of the appearance of a disease among unvaccinated sheep is carried out at any time. During vaccination, castration and shearing of sheep is prohibited. In farms that are permanently unaffected by anaerobic dysentery in lambs, all born lambs are injected with antitoxic serum.

Ministry agricultural policy Ukraine

Kharkov State Veterinary Academy

Department of Epizootology and Veterinary Management

Abstract on the topic:

"Anaerobic dysentery of lambs"

The work was prepared by:

3rd year student, 9th group of FVM

Bocherenko V.A.

Kharkov 2007

Definition of disease

Historical background, distribution, degree of danger and damage.

The causative agent of the disease.

Epizootology

Pathogenesis

Prevention

Control measures

Definition of disease

Anaerobic dysentery ( lat. - Dysenteria neonatorum anaerobica, Dysetenteria anaerobica agnellorum; English - Lamb dysentery; white diarrhea, anaerobic enterotoxemia of lambs) is an acute toxic-infectious disease of newborn lambs, characterized by hemorrhagic diarrhea, toxemia and death.

Historical background, distribution, degree of danger and damage.

Lamb dysentery was first described as bloody diarrhea in 1885 by P.A. Kuleshov et al. The etiology of the disease was studied by Delling and Geiger (1922), who identified the causative agent and gave the name of the disease. Anaerobic dysentery is recorded in many sheep-raising countries (it has no epizootological significance on the North American continent) and causes damage due to the death of lambs.

The causative agent of the disease

C. perfringens types C and D is a large, thick, rod-shaped gram-positive bacterium with slightly rounded ends, sometimes shaped like a thread with pointed ends. It does not have flagella, therefore, unlike other clostridia, it is motionless. In the body of animals and on serum media it forms capsules; in the external environment and on alkaline carbohydrate-free media it forms central or subterminal spores.

The pathogen in spore form persists in soil for up to 4 years, on dry surfaces for up to 2 years. The spores are not very resistant to temperature; they can withstand boiling for 5...15 minutes, heating at 90°C for 30 minutes.

Vegetative forms of the microbe persist in soil from 10 to 35 days, in manure for 3...5 days. At a temperature of 80 °C they die within 5 minutes. Disinfectants (10% solution of hot sodium hydroxide and 1% sulfur-carbolic mixture, bleach solution containing 5% active chlorine, 5% formaldehyde solution) kill the pathogen in 15...20 minutes.

Epizootology

Anaerobic dysentery affects newborn lambs aged from several hours to 10 days, more often 2...5 days. At older ages, animals rarely get sick.

The source of the infectious agent is sick animals that excrete the pathogen in their feces, as well as healthy adult sheep that are carriers of the bacilli, in whose intestines the pathogen can multiply and be periodically excreted during external environment with feces, infecting the soil, litter, and care items. Spores can persist in the soil for a long time, which determines the stationary (enzootic) nature of anaerobic dysentery.

The disease is not contagious. Infection of lambs occurs through nutritional means when sucking an udder contaminated with secretions of sick animals, or when licking infected objects (feeder, bedding, etc.). No less dangerous are the uncleaned corpses of dead lambs, the places where they lay undisinfected, etc.

The disease is seasonal and manifests itself during mass lambing. One of the reasons for the occurrence of the disease is incomplete vaccination coverage of the ewes, a decrease in the formation of colostral immunity due to low fatness of animals.

In some farms, the disease is registered annually, in others it is not observed for a number of years, which depends on the presence of factors contributing to the disease (hypothermia, unsatisfactory living conditions for lambs, crowded sheds, poor feeding of ewes). Characterized by an increase in the epizootic outbreak from isolated cases to mass destruction of lambs by the 15th...20th day after the appearance of the first cases.

In dysfunctional farms, the incidence fluctuates from year to year - from isolated cases to 15...30% of lambs from a dysfunctional flock, mortality can reach 100%.

Pathogenesis

The disease develops as a type of intestinal intoxication. The pathogen, once in the gastrointestinal tract, quickly multiplies and releases a large amount of a complex of toxins (mainly beta toxin), which have a necrotizing effect on intestinal tissue, causing ulcers and focal necrosis. Having penetrated through damaged intestinal walls into other organs and tissues, the toxin causes general intoxication of the body.

The occurrence of dysentery in lambs only in the first days of life is explained by lower production of trypsin during this period, as well as the presence of a trypsin inhibitor in sheep colostrum. Animals older than 15 days of age do not get sick, since they produce a sufficient amount of trypsin, which neutralizes beta toxin.

Course and clinical manifestation

The incubation period for anaerobic dysentery is up to 5...6 hours, rarely 2...3 days. In most cases, lambs become ill within the first 3 days after birth. The course of the disease is hyperacute, acute, subacute and rarely chronic.

At hyperacute course lambs die unexpectedly, without any obvious clinical symptoms, or the disease lasts no more than 2...4 hours. In this case, signs of damage to the nervous system are characteristic - impaired coordination of movement, convulsions. Sometimes, shortly before death, the feces become liquid and bloody. At acute course They note a depressed state, diarrhea with gas bubbles. The feces subsequently become thick, dark, mixed with mucus and often blood. A sick lamb stands bent over, with disheveled hair, a retracted belly and weakly reacts to its surroundings. The fur around the anus and on the tail is stained with feces and stuck together. At the onset of the disease, body temperature may rise to 41...42°C, breathing and pulse become more frequent. The disease lasts from several hours to several days, and the lamb dies due to symptoms of rapidly increasing general weakness.

At subacute course the disease takes on a protracted nature with less pronounced symptoms. In some animals it can last up to 2 weeks. The sick lamb lies in a state of prostration, it is exhausted; diarrhea occurs, the stool is initially liquid, yellow or green, and later becomes thicker, black, mixed with blood, gas bubbles and mucus. The animals are straining, the spine is arched, the stomach is retracted, the fur is ruffled. Sick lambs are depressed, lie down, refuse to suckle milk, their pulse and breathing are rapid. At the onset of the disease, body temperature can rise to 41 °C. Then they note exhaustion and death.

In rare cases, when chronic course Symptoms of the disease may not be clearly expressed, the disease drags on and the lambs recover. Recovery is very slow, lambs are stunted in growth and development and often die from various causes.

Pathological signs

Rigor mortis is well expressed. The anal area is soiled with feces. Upon opening in the chest and abdominal cavities, and also in the cardiac membrane they find yellow or reddish exudate, sometimes a gelatinous mass. The heart is somewhat dilated, the cardiac muscle is flabby, gray-red in color, with pinpoint and striped hemorrhages under the epicardium and endocardium. The liver is often enlarged, blood-filled, and has a flabby consistency. The spleen is without visible changes. The lungs are swollen, the kidneys are hyperemic. Most characteristic changes found in gastrointestinal tract, especially in the thin section. The abomasum is slightly inflamed and often filled with curdled milk. In some cases, the entire intestine is hemorrhagically inflamed, dark red in color, and filled with mucous-bloody contents. In other cases, individual sections of the intestine are inflamed, covered with ulcerations and round necrotic foci with a diameter of 3 to 6 mm, surrounded by a hemorrhagic zone. Mesenteric lymph nodes are enlarged, juicy, sometimes with hemorrhages. In hyperacute cases, there are no visible pathological changes.

Diagnosis and differential diagnosis

The disease is preliminarily diagnosed based on epidemiological data, clinical picture and pathological changes. The presence of hemorrhagic enteritis or necrotic ulcers on the intestinal wall in dead lambs can be considered as diagnostic sign. The final diagnosis is made based on the results of bacteriological and serological studies.

The material for laboratory research is a fresh corpse or a bandaged segment of the affected intestine, parts of parenchymal organs, mesenteric lymph nodes, tubular bone and sterile collected contents thin section intestines. The material is taken no later than 3 hours after the death of the animal.

Laboratory diagnosis (microscopy, cultural and biological examination) is established similarly to that for infectious enterotoxemia. If a toxin is detected in the filtrate of intestinal contents or an isolated culture, its type is determined in the pH of white mice with type-specific sera to C. perfringens.

At differential diagnosis it is necessary to exclude salmonellosis, escherichiosis, and coccidiosis.

Immunity and specific prevention

With dysentery, as with other clostridioses, antitoxic immunity is formed - recovered animals acquire stable immunity to recurrent illness. Lambs obtained from vaccinated ewes develop colostral immunity that lasts up to 1.5 months.

To prevent dysentery in lambs, ewes are vaccinated before lambing. For this purpose, a polyvalent concentrated aluminum hydroxide vaccine or a polyvalent toxoid against sheep clostridiosis is used. For passive immunization, antitoxic serum is used against anaerobic dysentery of lambs and infectious enterotoxemia of sheep (see Infectious enterotoxemia of sheep).

Prevention

Pregnant ewes are provided with adequate feeding, especially in the last third of pregnancy, when fetal growth is most intense. It is necessary to strictly observe the rules of hygiene when preparing for lambing. The premises are provided with veterinary and sanitary conditions. Rooms for newborns, maternity wards, dispensaries and equipment intended for caring for animals are periodically cleaned and disinfected. The lambed sheep are kept separately in small groups in special insulated rooms. Conduct timely feeding of newborns with colostrum. The first feeding of young animals should be carried out no later than 1...2 hours after birth.

Treatment

Treatment is effective only at the beginning of the disease. When dysentery appears, sick lambs along with ewes are isolated and treated with antitoxic serum against anaerobic dysentery of lambs and infectious enterotoxemia of sheep. The serum can be used in combination with tetracycline antibiotics. Sick animals are kept in isolation (suckling lambs with their mothers) and served separately from healthy livestock.

Control measures

In disadvantaged farms, all sheep are subject to vaccination, starting from 3 months of age, according to the instructions for using the vaccine or polyanatoxin. In farms affected by dysentery of lambs and malignant edema of sheep, preventive vaccination of pregnant queens is carried out 1.5-2 months before the start of lambing. Upon reaching 6 months of age, lambs are revaccinated twice in doses prescribed for adult sheep. Forced vaccination in the event of the appearance of a disease among unvaccinated sheep is carried out at any time. During the vaccination period, castration and shearing of sheep are prohibited. In farms (flocks) permanently affected by anaerobic dysentery, all born lambs are injected with antitoxic serum.

Bibliography

1. Bakulov I.A. Epizootology with microbiology Moscow: "Agropromizdat", 1987. - 415 p.

2. Infectious diseases animals / B.F. Bessarabov, E.S. Voronin and others; Ed. A.A. Sidorchuk. - M.: KolosS, 2007. - 671 p.

3. Altukhov N.N. A short reference book for a veterinarian Moscow: "Agropromizdat", 1990. - 574 p.

4. Doctor of veterinary medicine / P.I. Verbitsky, P.P. Dostoevsky. - K.: "Harvest", 2004. - 1280 p.

5. Directory of a veterinarian / A.F. Kuznetsov. - Moscow: "Lan", 2002. - 896 p.

6. Directory of a veterinarian / P.P. Dostoevsky, N.A. Sudakov, V.A. Atamas et al. - K.: Harvest, 1990. - 784 p.

7. Gavrish V.G. Veterinarian's Handbook, 4th ed. Rostov-on-Don: "Phoenix", 2003. - 576 p.

Ministry of Agrarian Policy of Ukraine

Kharkov State Veterinary Academy

Department of Epizootology and Veterinary Management

Abstract on the topic:

"Anaerobic dysentery of lambs"

The work was prepared by:

3rd year student, 9th group of FVM

Bocherenko V.A.

Kharkov 2007

Definition of disease

Historical background, distribution, degree of danger and damage.

The causative agent of the disease.

Epizootology

Pathogenesis

Prevention

Control measures

Definition of disease

Anaerobic dysentery ( lat. - Dysenteria neonatorum anaerobica, Dysetenteria anaerobica agnellorum; English - Lamb dysentery; white diarrhea, anaerobic enterotoxemia of lambs) is an acute toxic-infectious disease of newborn lambs, characterized by hemorrhagic diarrhea, toxemia and death.

Historical background, distribution, degree of danger and damage.

Lamb dysentery was first described as bloody diarrhea in 1885 by P.A. Kuleshov et al. The etiology of the disease was studied by Delling and Geiger (1922), who identified the causative agent and gave the name of the disease. Anaerobic dysentery is recorded in many sheep-raising countries (it has no epizootological significance on the North American continent) and causes damage due to the death of lambs.

The causative agent of the disease

C. perfringens types C and D is a large, thick, rod-shaped gram-positive bacterium with slightly rounded ends, sometimes shaped like a thread with pointed ends. It does not have flagella, therefore, unlike other clostridia, it is motionless. In the body of animals and on serum media it forms capsules; in the external environment and on alkaline carbohydrate-free media it forms central or subterminal spores.

The pathogen in spore form persists in soil for up to 4 years, on dry surfaces for up to 2 years. The spores are not very resistant to temperature; they can withstand boiling for 5...15 minutes, heating at 90°C for 30 minutes.

Vegetative forms of the microbe persist in soil from 10 to 35 days, in manure for 3...5 days. At a temperature of 80 °C they die within 5 minutes. Disinfectants (10% solution of hot sodium hydroxide and 1% sulfur-carbolic mixture, bleach solution containing 5% active chlorine, 5% formaldehyde solution) kill the pathogen in 15...20 minutes.

Epizootology

Anaerobic dysentery affects newborn lambs aged from several hours to 10 days, more often 2...5 days. At older ages, animals rarely get sick.

The source of the infectious agent is sick animals that excrete the pathogen in their feces, as well as healthy adult sheep-bacillus carriers, in whose intestines the pathogen can multiply and periodically be released into the external environment with feces, infecting the soil, bedding, and care items. Spores can persist in the soil for a long time, which determines the stationary (enzootic) nature of anaerobic dysentery.

The disease is not contagious. Infection of lambs occurs through nutritional means when sucking an udder contaminated with secretions of sick animals, or when licking infected objects (feeder, bedding, etc.). No less dangerous are the uncleaned corpses of dead lambs, the places where they lay undisinfected, etc.

The disease is seasonal and manifests itself during mass lambing. One of the reasons for the occurrence of the disease is incomplete vaccination coverage of the ewes, a decrease in the formation of colostral immunity due to low fatness of animals.

In some farms, the disease is registered annually, in others it is not observed for a number of years, which depends on the presence of factors contributing to the disease (hypothermia, unsatisfactory living conditions for lambs, crowded sheds, poor feeding of ewes). Characterized by an increase in the epizootic outbreak from isolated cases to mass destruction of lambs by the 15th...20th day after the appearance of the first cases.

In dysfunctional farms, the incidence fluctuates from year to year - from isolated cases to 15...30% of lambs from a dysfunctional flock, mortality can reach 100%.

Pathogenesis

The disease develops as a type of intestinal intoxication. The pathogen, once in the gastrointestinal tract, quickly multiplies and releases a large amount of a complex of toxins (mainly beta toxin), which have a necrotizing effect on intestinal tissue, causing ulcers and focal necrosis. Having penetrated through damaged intestinal walls into other organs and tissues, the toxin causes general intoxication of the body.

The occurrence of dysentery in lambs only in the first days of life is explained by lower production of trypsin during this period, as well as the presence of a trypsin inhibitor in sheep colostrum. Animals older than 15 days of age do not get sick, since they produce a sufficient amount of trypsin, which neutralizes beta toxin.

Course and clinical manifestation

The incubation period for anaerobic dysentery is up to 5...6 hours, rarely 2...3 days. In most cases, lambs become ill within the first 3 days after birth. The course of the disease is hyperacute, acute, subacute and rarely chronic.

At hyperacute course lambs die unexpectedly, without pronounced clinical symptoms, or the disease lasts no more than 2...4 hours. In this case, signs of damage to the nervous system are characteristic - impaired coordination of movement, convulsions. Sometimes, shortly before death, the feces become liquid and bloody. At acute course They note a depressed state, diarrhea with gas bubbles. The feces subsequently become thick, dark, mixed with mucus and often blood. A sick lamb stands bent over, with disheveled hair, a retracted belly and weakly reacts to its surroundings. The fur around the anus and on the tail is stained with feces and stuck together. At the onset of the disease, body temperature may rise to 41...42°C, breathing and pulse become more frequent. The disease lasts from several hours to several days, and the lamb dies due to symptoms of rapidly increasing general weakness.

At subacute course the disease takes on a protracted nature with less pronounced symptoms. In some animals it can last up to 2 weeks. The sick lamb lies in a state of prostration, it is exhausted; diarrhea occurs, the stool is initially liquid, yellow or green, and later becomes thicker, black, mixed with blood, gas bubbles and mucus. The animals are straining, the spine is arched, the stomach is retracted, the fur is ruffled. Sick lambs are depressed, lie down, refuse to suckle milk, their pulse and breathing are rapid. At the onset of the disease, body temperature can rise to 41 °C. Then they note exhaustion and death.

In rare cases, when chronic course Symptoms of the disease may not be clearly expressed, the disease drags on and the lambs recover. Recovery is very slow, lambs are stunted in growth and development and often die from various causes.

Pathological signs

Rigor mortis is well expressed. The anal area is soiled with feces. At autopsy, yellow or reddish exudate, sometimes a gelatinous mass, is found in the chest and abdominal cavities, as well as in the cardiac membrane. The heart is somewhat dilated, the cardiac muscle is flabby, gray-red in color, with pinpoint and striped hemorrhages under the epicardium and endocardium. The liver is often enlarged, blood-filled, and has a flabby consistency. The spleen is without visible changes. The lungs are swollen, the kidneys are hyperemic. The most characteristic changes are found in the gastrointestinal tract, especially in the thin section. The abomasum is slightly inflamed and often filled with curdled milk. In some cases, the entire intestine is hemorrhagically inflamed, dark red in color, and filled with mucous-bloody contents. In other cases, individual sections of the intestine are inflamed, covered with ulcerations and round necrotic foci with a diameter of 3 to 6 mm, surrounded by a hemorrhagic zone. Mesenteric lymph nodes are enlarged, juicy, sometimes with hemorrhages. In hyperacute cases, there are no visible pathological changes.

Diagnosis and differential diagnosis

The disease is preliminarily diagnosed based on epidemiological data, clinical picture and pathoanatomical changes. The presence of hemorrhagic enteritis or necrotic ulcers on the intestinal wall in dead lambs can be considered a diagnostic sign. The final diagnosis is made based on the results of bacteriological and serological studies.

The material for laboratory research is a fresh corpse or a bandaged segment of the affected intestine, parts of parenchymal organs, mesenteric lymph nodes, tubular bone and sterilely taken contents of the small intestine. The material is taken no later than 3 hours after the death of the animal.

Laboratory diagnosis (microscopy, cultural and biological examination) is established similarly to that for infectious enterotoxemia. If a toxin is detected in the filtrate of intestinal contents or an isolated culture, its type is determined in the pH of white mice with type-specific sera to C. perfringens.

In differential diagnosis, it is necessary to exclude salmonellosis, escherichiosis, and coccidiosis.

Immunity and specific prevention

With dysentery, as with other clostridioses, antitoxic immunity is formed - recovered animals acquire stable immunity to recurrent disease. Lambs obtained from vaccinated ewes develop colostral immunity that lasts up to 1.5 months.

To prevent dysentery in lambs, ewes are vaccinated before lambing. For this purpose, a polyvalent concentrated aluminum hydroxide vaccine or a polyvalent toxoid against sheep clostridiosis is used. For passive immunization, antitoxic serum is used against anaerobic dysentery of lambs and infectious enterotoxemia of sheep (see Infectious enterotoxemia of sheep).

Prevention

Pregnant ewes are provided with adequate feeding, especially in the last third of pregnancy, when fetal growth is most intense. It is necessary to strictly observe the rules of hygiene when preparing for lambing. The premises are provided with veterinary and sanitary conditions. Rooms for newborns, maternity wards, dispensaries and equipment intended for caring for animals are periodically cleaned and disinfected. The lambed sheep are kept separately in small groups in special insulated rooms. Conduct timely feeding of newborns with colostrum. The first feeding of young animals should be carried out no later than 1...2 hours after birth.

Treatment

Treatment is effective only at the beginning of the disease. When dysentery appears, sick lambs along with ewes are isolated and treated with antitoxic serum against anaerobic dysentery of lambs and infectious enterotoxemia of sheep. The serum can be used in combination with tetracycline antibiotics. Sick animals are kept in isolation (suckling lambs with their mothers) and served separately from healthy livestock.

Control measures

In disadvantaged farms, all sheep are subject to vaccination, starting from 3 months of age, according to the instructions for using the vaccine or polyanatoxin. In farms affected by dysentery of lambs and malignant edema of sheep, preventive vaccination of pregnant queens is carried out 1.5-2 months before the start of lambing. Upon reaching 6 months of age, lambs are revaccinated twice in doses prescribed for adult sheep. Forced vaccination in the event of the appearance of a disease among unvaccinated sheep is carried out at any time. During the vaccination period, castration and shearing of sheep are prohibited. In farms (flocks) permanently affected by anaerobic dysentery, all born lambs are injected with antitoxic serum.

Bibliography

1. Bakulov I.A. Epizootology with microbiology Moscow: "Agropromizdat", 1987. - 415 p.

2. Infectious diseases of animals / B.F. Bessarabov, E.S. Voronin and others; Ed. A.A. Sidorchuk. - M.: KolosS, 2007. - 671 p.

3. Altukhov N.N. A short reference book for a veterinarian Moscow: "Agropromizdat", 1990. - 574 p.

4. Doctor of veterinary medicine / P.I. Verbitsky, P.P. Dostoevsky. - K.: "Harvest", 2004. - 1280 p.

5. Directory of a veterinarian / A.F. Kuznetsov. - Moscow: "Lan", 2002. - 896 p.

6. Directory of a veterinarian / P.P. Dostoevsky, N.A. Sudakov, V.A. Atamas et al. - K.: Harvest, 1990. - 784 p.

7. Gavrish V.G. Veterinarian's Handbook, 4th ed. Rostov-on-Don: "Phoenix", 2003. - 576 p.

Anaerobic dysentery of calves (Dysenteria neonatorum anaerobica) is an acute toxicoinfectious disease of newborn lambs, characterized by hemorrhagic enterotoxemia. Piglets, calves are sick, fur animals.

Pathogen information . Cl. perfringens type B (P.N. Kuleshov, 1885; Dalling, Geiger, 1992; in the USSR M.D. Polykovsky, 1936), producing rtoxin with hemolytic, neurotoxic and necrotizing effects; has the form of short immobile rods, forms capsules and spores.

When boiling, microbial spores are destroyed in 10-80 minutes. When dried, the pathogen dies in 1-2 days.

Epizootology. Clinical signs. Lambs are susceptible in the first days of life, less often - at 5-6 days of age, very rarely - at 2 weeks of age. The course of the disease is acute.

The incubation period ranges from several hours to 2-3 days. Characteristic sign diseases - liquid feces, initially light yellow, and then thick with blood or bloody. Sick animals lie down more and refuse food.

Pathological changes . The most characteristic changes in the small intestine are hemorrhagic inflammation of the intestinal mucosa and abomasum, ulcerations, and necrotic foci. The mesenteric and portal lymph nodes are sharply enlarged; on section they are juicy, colored dark red, and riddled with hemorrhages. In the liver and kidneys, the phenomenon of congestive hyperemia, granular and fatty degeneration.

Diagnostics

Laboratory tests include detecting the toxin in the contents of the small intestine, isolating a pure culture and typing it. For research in the laboratory they are sent to fresh a bandaged section of the affected intestine with contents, parenchymal organs, mesenteric lymph nodes, tubular bone.

Differential diagnosis. Differentiate from colibacillosis and salmonellosis. Colibacillosis occurs only in 1-5 day old lambs, but sometimes in older ones as well. There are no necrotic inflammations and ulcers of the intestinal mucosa, the spleen is enlarged, and E. coli is isolated during bacterial examination.

Adults also suffer from salmonellosis. A sharp enlargement of the spleen during autopsy, absence of ulcers in the intestines. Bacterial growth is detected in crops.

Treatmenteffective in initial stage diseases. Antitoxic serum is used against anaerobic dysentery and infectious enterotoxemia, which is administered subcutaneously at a dose of 200-400 AE 2 times a day.

Prevention.To create immunity, pregnant sheep are vaccinated, and lambs are immunized with antitoxic serum.

Veterinary and sanitary examination . Sick animals are not allowed to be slaughtered. If a disease is detected on the conveyor belt, the carcass with all organs and skin is destroyed. For disinfection of lamb dysentery, a hot 10% sodium hydroxide solution is recommended.

Anaerobic dysentery of lambs- acute infection newborn lambs, characterized by hemorrhagic enterotoxemia.

The causative agent of the disease, the anaerobic microbe Clostridium perfringens, persists in spore form in the soil until four years: tolerates boiling for 5-9 minutes, at 90° C - 30 minutes. In vegetative form, the microbe survives in the soil for 10-35 days, in manure - 3-5 days.

Ten percent essence of sodium hydroxide, ten percent essence of sulfur-carbol mixture, essence of bleach, including 5% active chlorine, five percent essence of formaldehyde destroy the pathogen in 15-20 minutes.

Epizootology. IN normal conditions Mostly lambs of fine-wool breeds under the age of 5 days get sick, older ones get sick less often. The disease is epizootic in nature and manifests itself in winter and early spring period during the mass lambing stage. Piglets, fur-bearing animals, young cattle and chickens are also infected.

Pathogen source anaerobic dysentery of lambs– are lambs and adult sheep-bacillus carriers, in whose intestines the pathogen is capable of multiplying and from time to time being released into the external environment with feces.

This leads to contamination of the soil, bedding, and animal care items and serves as the root cause of the stationary nature of the disease.

Infection of lambs occurs through nutritional means when sucking an udder contaminated with the excreta of diseased animals. At the beginning of an epizootic outbreak, isolated cases diseases of lambs, then the number of sick people gradually increases.

Irrational and insufficient feeding of ewes, failure to comply with zoohygienic standards for keeping them at pregnancy, cooling or overheating of newborn lambs contribute to the occurrence and spread of this disease.

The disease affects 15-30% of lambs from a dysfunctional flock. The fatal outcome ranges from 50 to 100%.

Immunity. Animals that have suffered from the disease receive intense immunity.

Signs. The incubation stage for anaerobic dysentery lasts from several hours to 2-3 days.

The disease occurs acutely and subacutely.

With acute continuation of the disease, lambs die a few hours after birth without obvious clinical symptoms, and sometimes before fatal bloody feces are observed.

With subacute continuation, the first symptom of the disease is loose stool. The excrement is initially liquid, yellow or greenish in color, but later becomes thicker and darker, interspersed with blood, gas bubbles and mucus.

Unhealthy lambs are depressed, stand almost all the time, stop suckling their mother, the tail and hair around the anus are dirty and stuck together with feces.

First, the animal’s body temperature rises to 41 °C, then quickly drops. Soon a breakdown sets in, and the lambs die with signs of increasing weakness and intense exhaustion.

IN in some cases the disease becomes protracted. The animal seems to be slowly recovering, but then very often dies from various complications.

Pathological changes. In dead lambs, hemorrhagic inflammation of the mucous membrane of the abomasum and intestines is found. The mucous membrane is thicker than normal, covered with ulcers, with foci of necrosis, the lumen is filled with bloody mucus. With acute continuation of the disease, only the intestinal vessels become hyperemic. The liver is often larger than normal, flabby in composition, and filled with blood. The spleen is without noticeable changes. The heart muscle is flabby, strewn with pinpoint and banded hemorrhages. The kidneys are flabby, slightly larger than normal, and there may be hemorrhages under the capsule. The pathological picture is typical for general toxicosis.

Diagnostics. The diagnosis is established based on the analysis of epizootological data, specific clinical symptoms, pathological and anatomical changes and the results of bacteriological and toxicological studies. It is possible to isolate a culture of the causative agent of dysentery in lambs from parenchymal organs and blood in rare cases. Identification of CI. perfringens type B and its toxins in the intestines of newborn lambs actually represents evidence of their disease.

Dysentery in lambs must be distinguished from dyspepsia, colibacillosis and salmonellosis, which is realized on the basis of clinical and epidemiological data, anatomy and laboratory study results.

Treatment. It is effective only at the beginning of the disease. It is recommended to use hyperimmune serum and antibiotics (such as biomycin, syntomycin).

Excellent healing effect has syntomycin, prescribed in the amount of 0.1-0.2 grams orally 2-3 times a day for three days. Norsulfazole is given with food 2-3 times a day in the amount of 0.04-0.06 g/kg of animal weight. In all cases, symptomatic treatment is used.

Prevention and control measures. Pregnant ewes must be provided with good nutrition, especially in the last third of pregnancy, when fetal growth is to the greatest extent intense.

For pregnant ewes and newborn lambs, it is necessary to create very good conditions content. In the premises it is necessary to strictly observe the veterinary and sanitary regime, to prevent dampness, dirt and drafts from appearing.

From time to time, the premises and equipment are cleaned and disinfected. In winter, sheep with offspring are kept in small groups in deliberately insulated sheds.

When dysentery occurs, unhealthy lambs together with ewes are separated from everyone else and treated.

The sheds are cleaned and disinfected with a ten percent solution of bleach and a 5% creolin emulsion.

Antibiotics, antitoxic serum and vaccine are used. The serum must be administered to lambs within 1-2 hours after they are born. It is more reasonable to create immunity in lambs through colostrum during vaccinated ewes.

It is recommended to vaccinate pregnant queens a month before lambing. To prevent dysentery in lambs, a polyvalent concentrated GOA vaccine and polyanatoxin are used.

For passive immunization of lambs, bivalent serum against infectious enterotoxemia of sheep and dysentery of lambs is used.