Endocrine system of the dog. Metabolic diseases and endocrinological syndromes in dogs. OKNs that secrete excess sex steroids

The endocrine system of dogs, like other animals, is a very complex mechanism, the operation of which depends on many factors. Therefore, even minor physiological changes may lead to hormonal imbalance. As a rule, any changes in the endocrine system almost always make themselves felt, in particular this affects the behavior and appearance of the pet. Moreover, hormonal imbalance can lead to changes in the digestive, nervous and cardiovascular systems.

Symptoms of hormonal disorders

As you know, hormonal disorders are common among mature pets: nulliparous and unsterilized dogs are especially susceptible. But, as already said, it depends on many factors.

Regarding symptoms that indicate changes in hormone levels, then it largely depends on the breed of the animal. For example, if this is a fighting breed, then first of all the changes will be reflected in the behavior and emotions of the pet. If we are talking about a long-haired breed, then disruptions in the endocrine system will, first of all, be noticeable by the appearance of the coat.

Before highlighting the main manifestations of hormonal disorders, it is necessary to highlight the most common diseases: hypothyroidism, diabetes mellitus, polycystic ovary syndrome, pyometra and Cushing's syndrome. As you can see, dogs are susceptible to the same diseases as people. An interesting fact is that hypothyroidism is much more common than hyperthyroidism, not only among animals, but also among people. Based on this, it can be distinguished following symptoms which may indicate hormonal imbalance:

• Apathy, constant fatigue and general weakness in the pet, unusual for its breed.
• Hair loss or deterioration in its quality.
• Unreasonable aggression and increased excitability.
• Intolerance to cold, which is not usually characteristic of dogs.
• Enlargement of the vulva.
• A short period of time between heats, hypertonicity of the genitals.
• Bloody vaginal discharge, without signs of pregnancy.
• Rapid gain of fat mass or obesity.
• Constant thirst for water.
• Muscle weakness.
• Reduced immunity, susceptibility to colds and viruses.

If at least one symptom is present in your pet, then you should be sure to consult a veterinarian. In such cases, the animal must be diagnosed and subsequently treated. Pets often undergo surgery. It is worth noting that the listed Clinical signs they cannot all exist at the same time.

Causes of hormonal disorders

The main factors that take the animal’s body “by surprise” include:

• The use of contraceptives against estrus.
• Poor nutrition.
• Stress.
• Lack of iodine in the body.
• The presence of diseases that contribute to hormonal changes.
• Pituitary tumor.

Interesting fact! Dogs' bodies, more than other animals, produce oxytocin, the so-called love hormone. It is he who makes these animals be loyal.

Treatment of diseases

As a rule, diagnosed dog diseases associated with impaired hormone production are treated only by therapeutic or surgical means. In other words, there are practically no folk methods for combating illnesses for pets. However, if the cause is related to digestive diseases, then the dog owner should take care proper nutrition your animal. Treatment unpleasant symptoms directly depends on the disease.

So, if you pet hypothyroidism is diagnosed, the doctor will prescribe hormone therapy, using thyroxine. In severe or advanced forms, the disease is treated surgically. The main manifestations of hypothyroidism are: apathy, muscle weakness, deterioration in wool quality, and in some cases obesity. The reasons have not been fully identified, but hormones thyroid gland may be caused by iodine deficiency or severe stress animal.

Hyperthyroidism, unlike hypothyroidism, is much less common, but if the disease occurs, veterinary specialists usually advise playing and walking with the pet more so that the animal is active. Usually, increased level thyroid hormones may manifest itself in aggression and increased excitability. Thyroxine synthesis decreases somewhat with physical activity.

Diseases such as Cushing's syndrome or pyometra are usually caused by the presence of a tumor. Pyometra is usually accompanied by bloody vaginal discharge and frequent estrus of the animal. In this case, the tumor is inside or next to reproductive organs. Cushing's syndrome occurs due to stress and usually leads to muscle weakness or obesity. If identified physiological reasons these diseases, the doctor will prescribe hormonal therapy using synthetic estrogens or progestins.

Much more difficult to diagnose. The fact is that in both people and animals this disease does not make itself felt for a long time. However, the disease can be noticed by the quality of the coat or by constant thirst pet. The disease is practically incurable: the animal is prescribed periodic insulin injections.

Actually the list hormonal diseases very wide. The ones listed are among the most common. It is worth considering that many diseases have similar symptoms, but different pathogenesis of development. Dog owners should be extremely attentive to their pets.

04/06/2016, 18:00

Baldness and dermatoses- These are diseases of the skin and hair that not only spoil the appearance, but also greatly complicate the life of the animal. Alopecia (baldness) leads to baldness, and dermatosis irritates the skin. There are many reasons that provoke these diseases, and one of them is an imbalance of sex hormones. Your veterinarian will likely suggest therapy or try to either lower or raise your hormone levels back to normal. How can we determine that a dog is suffering precisely because of an imbalance of sex hormones?

Symptoms:

1. Soft or dry brittle fur.
2. Dandruff.
3. Darkening of the skin.
4. Acne on the skin.
5. Abnormal skin appearance or shape of the nipples, breasts, vulva, foreskin of the penis or clitoris, testicles, ovaries and prostate gland.
6. Secondary bacterial infection.
7. Inflammation of the outer ear with copious discharge sulfur.
8. A lack of estrogen and testosterone can result in urinary incontinence.

Where does hair fall out first?

1. The perineum (the area between the vulva/scrotum and the anus).
2. Stomach.
3. Hips.
4. Back of the neck.

Causes:

As a rule, animals that have impaired hormonal balance. Depending on what type of disorder is present in the dog’s body, the specialist selects treatment.

One of the reasons is secondary ovarian dysfunction in bitches due to:

• low level of production of sex hormones in the adrenal gland;
• false pregnancy;
• metabolic disorders;
• hormonal imbalance after spaying in intact bitches;
• baldness of the groin and darkening of the skin in Edel Terriers, Boxers and English bulldogs.

Dachshunds and boxers are most susceptible to this disease.

Primary ovarian dysfunction (hyperestrogenism in bitches)
This condition may be associated with ovarian cysts (especially in English Bulldogs), ovarian tumors (rare), or overdose of estrogen medications. More often, this dysfunction affects older animals.

Increased estrogen levels in male dogs (hyperestrogenism)

Causes:

• excess estrogen due to testicular tumor;
• Cryptorchidism is a dysfunction of the testes due to undescended testicles.

Boxers, Shelties, and german shepherds, Weimar Pointers, Cairn Terriers, Pekingese and Collies.

Pseudohermaphroditism (a developmental disorder in which the internal genitalia of one sex are combined with the external genitalia of the other sex) occurs in miniature schnauzers. Dermatosis in males is treated with testosterone. The pathology is associated with a decrease in androgen levels. It may occur against the background of atrophy and tumors of the testes.

Diagnostics

To make a correct diagnosis, your veterinarian will need full story your dog's health, including a history of symptoms, injuries and incidents that preceded the illness. The specialist must carefully examine your pet: conduct an external examination, do tests, including biochemical profile, full analysis blood, urine test, and electrolyte panels. A skin biopsy may be required to show the presence of sex hormones in the skin.

If necessary, your veterinarian will refer you for x-rays, ultrasound, and even laparoscopy (exploratory surgery where a small camera is inserted into the inside of the abdomen to examine organs). This will help detect ovarian or testicular abnormalities or a tumor.

To check adrenal function, an ACTH test may be required to test for the presence of the hormone adrenocorticotropin, and a test for adrenal dysfunction. Hormonal tests are also needed to check your testosterone levels.

Treatment

If your dog is suffering from hormonal imbalances, spaying or neutering is one of the main treatment options. If your dog is on estrogen therapy and the results are not good for his health, your veterinarian should stop the therapy. Anti-dandruff shampoo and medications to treat or prevent bacterial skin infections and itching will also be helpful.

Endocrine glands or endocrine system

There are three types of glands in the body: exocrine and endocrine and mixed.

Exocrine glands have their own excretory ducts, through which the secretion of these glands passes to the working organ. Examples of the action of exocrine glands: lacrimation when dust particles enter the eye, secretion of pancreatic juice when acidic food enters the duodenum, or increased formation of synovial fluid when a joint is damaged.

Endocrine glands do not have excretory ducts and secrete their secretions - hormones - into the blood, which carries them throughout the body. Hormones are specific chemical compounds that are produced in the endocrine glands.

Mixed glands are both exocrine and endocrine, because they produce both hormones that are carried into the blood and secretions that act “on the spot.” An example would be the pancreas or gonads.

According to their chemical nature, all hormones can be divided into four groups:

amine derivatives (tyrosine);

Peptides and proteins (insulin);

Steroids (adrenal hormones);

Fatty acid.

Endocrine glands include organs, tissues, and groups of cells that secrete hormones into the blood through the walls of capillaries.

The following endocrine glands exist in the form of organs: pituitary gland, pineal gland (epiphysis), thyroid and parathyroid glands, adrenal glands. Mechanisms of action and properties of hormones

The following mechanisms may be involved in the regulation of hormone secretion:

A. Presence of a specific metabolite in the blood. For example, excess glucose in the blood causes the pancreas to secrete insulin, which lowers blood glucose levels.

B. The presence of another hormone in the blood. For example, many hormones secreted by the anterior pituitary gland stimulate the secretion of hormones by other glands in the body.

B. Stimulation from the autonomic nervous system. For example, when there is anxiety, stress or danger, cells in the adrenal medulla begin to secrete adrenaline and norepinephrine.

In the first two cases, the time of hormone secretion and its amount is regulated according to the feedback principle. Both positive and negative feedback are involved in the regulation of the activity of the gland, but positive feedback, which increases the instability of the system, acts as part of the general regulatory mechanism. For example, the release of luteinizing hormone (LH) under the influence of estrogens is carried out according to the feedback principle, but its excessive secretion is prevented at the appropriate moment by progesterone, released under the influence of LH.

The secretion of hormones stimulated by some other hormone is usually under the control of the hypothalamus and pituitary gland, and the final metabolic or trophic effect may result from the secretion of three different hormones. This kind of cascade mechanism is of great importance, since thanks to it, the effect of small amounts of the original hormone in the endocrine chain is enhanced many times over.

Hormones have specificity and act only on those target cells that have special receptors of a protein or lipoprotein nature that react with this hormone. Cells that are not targets for this hormone do not have such receptors, and therefore the hormone does not affect them.

Many hormones have specific sites in their molecule responsible for attachment to the receptor.

The release of hormones from the adenohypophysis is regulated by feedback from the hormones of the target glands. This happens as follows: the pituitary hormone stimulates the corresponding peripheral gland, and the level of its hormones in the blood increases; this leads to suppression of the secretion of hypothalamic factor (liberin) and pituitary hormone; as a result, the activity of the peripheral gland decreases, and when the concentration of its hormones in the blood falls below a certain level, their inhibitory effect on the hypothalamus and pituitary gland decreases and the latter again increase the secretion of hormones.

PROPERTIES OF HORMONES

Hormones determine the intensity of protein synthesis, the size of cells, their ability to divide, the growth of the entire organism and its individual parts, the formation of sex and reproduction, various forms of adaptation and the maintenance of homeostasis; higher nervous activity. Hormones influence all these processes by activating the enzymes that carry out these processes. Target cells have special receptors for many hormones. Each type of hormone molecule can only bind to its receptor on the cell membrane.

SUMMARY TABLE OF THE MAIN ENDOCRINE GLANDS, THEIR FUNCTIONS AND WAYS OF REGULATION OF THEIR ACTIVITY

The main centers of coordination and integration of the functions of two regulatory systems (nervous and endocrine) are the hypothalamus and pituitary gland. The hypothalamus plays a leading role in collecting information from other parts of the brain and from its own blood vessels. This information is transmitted to the pituitary gland, which, by secreting specific hormones, directly or indirectly regulates the activity of all other endocrine glands.

Hypothalamus

The hypothalamus is located at the base of the forebrain directly below the thalamus and above the pituitary gland. It consists of several sections - nuclei, which are clusters of neuron bodies, the axons of which end on the blood capillaries in the median eminence and in the posterior lobe of the pituitary gland. The regulation of many physiological functions (hunger, thirst, sleep, production and release of heat) is carried out nervously with the help of impulses coming from the hypothalamus along the nerves of the autonomic systems. At the same time, control over endocrine secretion by the hypothalamus is based on its ability to record the content of metabolites and hormones in the blood. The information entering the hypothalamus, along with information from many other parts of the brain, is transmitted to the pituitary gland - either by releasing special hormones into the bloodstream, or through neurons. In the latter case, specialized neurons serve as transmitters - neurosecretory cells.

All nerve endings are isolated in synaptic endings chemical substances- mediators, but in neurosecretory cells this ability has reached especially high development. Substances formed in the bodies of these cells are packaged into granules or vesicles and transported along the axon with the axoplasmic current. The nerve endings of these cells form synapses on the capillaries, into which they release their secretion under the influence of nerve impulses passing along the axon. In certain areas of the anterior hypothalamus, vasopressin and oxytocin are formed, which then flow along the axons to the neurohypophysis. In other areas of the hypothalamus, stimulants (liberins) and inhibitors (statins) are formed.

Pituitary

The pituitary gland is a small red-brown gland. The pituitary gland is located at the base of the skull in the sella turcica of the carotid bone, is anatomically connected to the hypothalamus by a stalk and consists of two lobes - anterior and posterior.

Anterior lobe of the pituitary gland, or adenohypophysis. This section is formed from an upwardly directed outgrowth of the roof of the primary oral cavity. It is connected to the hypothalamus by blood vessels. The nerve endings of specialized nerve cells of the hypothalamus secrete two groups of substances into these blood vessels: liberins and statins. From the blood vessels, these factors enter the anterior pituitary gland, stimulate or inhibit the release of one or more “tropic” hormones, which are produced and stored here and act as specific regulators of other hormones. endocrine glands. “Tropic” hormones are released by the cells of the adenohypophysis into the bloodstream, distributed by the blood throughout the body and act on specific target organs.

Adrenocorticosteroid hormone (ACTH)- the main stimulator of the adrenal cortex. This hormone is released during stress, spreads through the bloodstream and reaches the target cells of the adrenal cortex; adrenaline and norepinephrine are released into the blood, which have a sympathetic effect on the body.

Luteinizing hormone (LH) is the main regulator of the biosynthesis of sex hormones in male and female gonads, as well as a stimulator of growth and maturation of follicles, ovulation, formation and functioning of the corpus luteum in the ovaries.

Follicle stimulating hormone (FSH) increases the sensitivity of follicles to the action of LH, and also stimulates spermatogenesis.

Thyroid-stimulating hormone (TSH) - the main regulator of the biosynthesis and secretion of thyroid hormones.

Somatotropic hormone or growth hormone (GH)- the most important regulator of body growth and protein synthesis in cells; also participates in the formation of glucose and the breakdown of fats; Part hormonal effects mediated through increased liver secretion of somatomedin (growth factor).

In addition to tropic hormones, the anterior lobe of the pituitary gland produces hormones that perform an independent function. Prolactin regulates lactation, differentiation of various tissues, growth and metabolic processes, instincts of nursing offspring. Lipotropins- regulators of fat metabolism.

Posterior lobe of the pituitary gland, or neurohypophysis. This section develops as an inferior extension of the hypothalamus. It does not synthesize any hormones, but only stores and releases two hormones - antidiuretic hormone (vasopressin) and oxytocin. Antidiuretic hormone and oxytocin are formed in the bodies of neurosecretory cells lying in the nuclei of the hypothalamus and transported along their axons to the neurohypophysis.

Antidiuretic hormone is released into the blood when the water content in plasma decreases; it enhances the reabsorption of water in the distal tubules and collecting ducts of the kidneys, and it is retained in the plasma. At the same time, the amount of urine decreases and its osmotic concentration increases.

Under the influence of vasopressin, the permeability of the collecting ducts of the kidney and the tone of the arterioles increase. Its entry into the general bloodstream occurs when the osmotic pressure of the blood plasma increases, as a result of which the osmoreceptors of the hypothalamus are activated. When the osmotic pressure of the blood plasma decreases, the activity of osmoreceptors is inhibited and the secretion of vasopressin decreases. Using this feedback mechanism, the constancy of the osmotic pressure of the blood plasma is regulated. If the synthesis, transportation, secretion or action of vasopressin is disrupted, diabetes insipidus(symptoms: passing large amounts of urine with low relative density (polyuria) and constant feeling thirst; in patients, diuresis exceeds the norm by at least 10 times. When water intake is limited, patients become dehydrated. The secretion of vasopressin is stimulated by a decrease in the volume of extracellular fluid, pain, some emotions, stress, as well as a number of drugs - caffeine, morphine, barbiturates. Alcohol and an increase in the volume of extracellular fluid reduce the release of the hormone. The effect of vasopressin is short-lived because it is quickly destroyed in the liver and kidneys

Oxytocin causes contractions of the uterus during childbirth and active removal of milk from the nipples. Sensitivity to oxytocin increases with the introduction of female sex hormones. The maximum sensitivity of the uterus to oxytocin is observed during ovulation and on the eve of childbirth. During these periods, the greatest release of the hormone occurs. The descent of the fetus through the birth canal stimulates the corresponding receptors, which transmit signals to the nuclei of the hypothalamus, which increase the secretion of oxytocin. During sexual intercourse, the secretion of the hormone increases the frequency and amplitude of uterine contractions, facilitating the transport of sperm into the oviducts. Oxytocin stimulates milk production by causing contraction of the myoepithelial cells lining the mammary ducts. As a result of increased pressure in the alveoli, milk is squeezed into large ducts and is easily released through the nipples. When the tactile receptors of the mammary glands are stimulated, impulses are sent to the neurons of the hypothalamic nucleus and cause the release of oxytocin from the neurohypophysis. The effect of oxytocin on milk production occurs 30-90 s after the start of nipple stimulation.

Pineal gland or pineal gland

The pineal gland is a tiny gland formed from the roof of the diencephalon and covered on top by the corpus callosum and cerebral hemispheres. The pineal gland has no direct connection with the central nervous system, but is richly supplied with blood vessels. It secretes hormones - melatonin, serotonin, antigonadotropin. The pineal gland innervates sympathetic neurons, which are influenced by the brain nuclei that receive signals from the photoreceptors of the retina, i.e. neurosecretion of the pineal gland depends on illumination. In the dark, melatonin synthesis increases, and this hormone, acting through the brain, changes the activity of the thyroid gland, adrenal glands and gonads. Melatonin acts on the brain and influences the timing of a number of physiological processes such as puberty, ovulation and sleep (melatonin administration induces sleep). The pineal gland plays the role of a “biological clock” and acts as an organ that converts periodic nervous activity caused by light into endocrine secretion. Melatonin regulates pigment metabolism.

Serotonin is a precursor to melatonin. Studies have shown that the content of serotonin in the pineal gland is greater than in other organs, and depends on the species, age of the animal, as well as on the light regime. It is subject to daily fluctuations with maximum levels during the daytime.

Epithelial body

Parathyroid glands - located near the wall of the thyroid glands in the form of two to four small round or oval bodies. These glands secrete the hormone parathyroid hormone. Secretion of parathyroid hormone maintains plasma calcium concentration at normal levels and reduces plasma phosphate concentration. The function of the parathyroid glands is regulated by a simple feedback mechanism. Reduced activity of the parathyroid glands - hypoparathyroidism - leads to a decrease in the level of calcium in the plasma and tissues as a result of its excretion in the urine; as a result, tetany may develop - a pathological tendency to prolonged muscle contraction. At the same time, phosphate excretion decreases, and its level in plasma increases.

Recently, the hormone calcitonin was discovered, which, in contrast to parathyroid hormone, causes a decrease in calcium concentration.

Thyroid

In dogs, the thyroid gland is located on the right and left on the wall of the trachea and has the appearance of oval-elongated lobes. There may be additional thyroid glands in the form of round and oval bodies located at the caudal edge of the main thyroid gland or in a chain on the trachea and above the pericardium. Inside the lobes there are follicles lined with secreting epithelium, which produce iodine-containing hormones - thyroxine(T3 ), triiodothyronine (T4 ) and thyrocalcitonin. These hormones (T3 and T4) are involved in the regulation of basal metabolism, growth and development, and thyrocalcitonin regulates the concentration of calcium in the plasma.

When the thyroid gland is activated by thyroid-stimulating hormone of the adenohypophysis, the cells of the secreting epithelium become cylindrical and on their inner surface microvilli appear.

Formation and secretion of thyroid hormones

Iodine enters the thyroid gland in the form of I ions, which are actively absorbed by secreting epithelial cells from the blood. Then the ions become iodine molecules, which react with the amino acid tyrosine, which is part of thyroglobulin, a protein secreted by secreting cells into the lumen of the follicle. Further iodination of tyrosine molecules and subsequent conversion leads to the formation of two thyroid hormones T3 and T4.

T function3 IT4

T3 and T4 have a great influence on many metabolic processes, including the metabolism of carbohydrates, proteins, fats and vitamins. Their main physiological effect is to increase the intensity of basal metabolism - calorigenic effect. The calorigenic effect is associated with an increase in oxygen absorption and the rate of enzymatic reactions. This ultimately leads to increased production of ATP and heat in the tissues.

Together with growth hormone, T3 and T4 stimulate protein synthesis, which leads to accelerated growth.

In many metabolic processes influenced by thyroxine, its role is to enhance the action of other hormones (insulin, adrenaline, etc.).

Regulation of thyroxine and triiodothyronine secretion

Thyroid hormones have a longer-lasting effect than most other hormones, so maintaining constant levels is vital. important for the body. This is one of the reasons why T3 and T4 are stored in the gland and are ready to be released into the blood at any time. The release of T3 and T4 from the thyroid gland is regulated by their concentration in the blood. This regulation is carried out at the level of the pituitary gland and hypothalamus according to the feedback principle. When the concentration of hormones becomes higher than that necessary to maintain a constant level of basal metabolism, they suppress the secretion of thyroid hormone-releasing hormone by the hypothalamus and thyroid-stimulating hormone by the pituitary gland. This mechanism is influenced by external factors, which, through the overlying centers of the brain, stimulate the release of thyrotropin-releasing hormone; As a result, the pituitary gland's sensitivity threshold to feedback signals changes.

List of abbreviations used: HAC – hyperadrenocorticism, OKN – tumor of the adrenal cortex, 17-GP – 17-hydroxyprogesterone.

To diseases endocrine system, which interfere with skin healing in dogs include GAK; hypothyroidism; diabetes.
Endocrine diseases that interfere with skin healing in cats include HAC; OKN, secreting excess sex steroids; diabetes; cellulite.

The most common among these pathologies in everyday veterinary practice are HAC, hypothyroidism in dogs and diabetes mellitus in both types of animals. Probability of developing the rest listed diseases below, but nevertheless we should not forget about them and should add them to the list differential diagnoses if appropriate symptoms are present. Also, the list does not indicate such a possible pathology in cats as hypothyroidism, since the likelihood of developing hypothyroidism in cats is extremely low and basically this pathology is either iatrogenic (as a consequence of thyroidectomy or treatment radioactive iodine patients with hyperthyroidism), or congenital. Since these cases are casuistic, we will not consider them. Besides, in Russian Federation Radioactive iodine treatment is not currently available.
At the same time, today the frequency of diagnosis of cases of both iatrogenic and spontaneous HAC in cats continues to increase. This is likely due to the development of specialization in small animal veterinary medicine, a better understanding of feline diseases, the desire of owners to conduct more complex examinations of their pets, growing awareness of this disease, greater familiarity veterinarians with many variants of disorders associated with excess glucocorticoids, and an increase in the life expectancy of domestic cats in principle 2.
In this article we will consider only aspects of pathologies of the endocrine system, united by cause-and-effect relationships with impaired regeneration of soft tissues, without touching on other clinical, diagnostic and treatment issues that might be of interest to the clinician when establishing these diagnoses. To confirm any of the diagnoses, we will need specific laboratory tests and visual diagnostic methods, the choice of which will be based on the characteristics of the anamnesis and clinical picture demonstrated by the patient. Discussion of methods differential diagnosis is also beyond the scope of this article.
It is important to understand that some of these diseases do not always lead directly to impaired tissue healing. In certain cases, they simply contribute to the development of an infectious (secondary bacterial or fungal) process, which, in turn, is the reason for the absence or slowdown of normal regeneration 7, 8.
Leather healthy dogs and cats are colonized by various bacterial and fungal organisms. They are usually non-pathogenic and, moreover, prevent colonization by pathogenic species of microorganisms through competition. Potential pathogenic microorganisms, such as coagulase-positive staphylococci, often colonize mucous membranes, including - oral cavity. Thus, these microorganisms can be introduced when an animal licks a diseased body surface.
Infection with Gram-negative species can result from oral-fecal or environmental contamination.
Majority skin infections develops when a combination of virulence factors and changes in skin condition allow microorganisms to overwhelm the skin's physical, chemical and immunological defenses. Often recurrent pyoderma is secondary to primary cutaneous or systemic diseases. This leads to epidermal damage, inflammation, and additional bacterial colonization and proliferation. Staphylococci and Malassezia also produce mutually beneficial growth factors. The vast majority of pyoderma in dogs is associated with coagulase-positive staphylococci. The most common species is Staphylococcus intermedius, and S. aureus, S. hyicus and S. schleiferi have also been isolated.
Superficial pyoderma characterized by a bacterial infection localized in the stratum corneum of the skin and in hair follicles. This form The disease is much less common in cats and is associated with a wider range of microorganisms, including S. intermedius, S. felis, S. aureus, Pasteurella multocida and anaerobes (although the latter are more common in abscesses). Methicillin-resistant species, including S. intermedius, S. aureus, and S. schleiferi, have recently been isolated from dogs and cats. The latter two bacterial species are likely associated with deeper, opportunistic infections12.
Secondary pyodermas are common early manifestations hypothyroidism and HAC, this skin disease may be noted even before the appearance of systemic clinical signs 8.

A detailed consideration of these pathologies from the point of view of skin lesions that impede tissue regeneration

One of the most common among them is the HAK of dogs. Sick dogs show a tendency to bruise, a decrease in the number of subcutaneous fat and skin stretch marks. The characteristic “fragility” appears not only in the skin, but also in the blood vessels. For example, after a banal puncture of a vein to take a blood sample or other even minor injuries, excessive bruising may occur. Rarely, bruising occurs due to metal staples in surgical suture installed several years ago. Subcutaneous tissue atrophy due to the catabolic effects of excess cortisol may also predispose to bruising. Wounds heal more slowly, probably due to the formation of a fragile, thin scar. Possible edge separation skin wounds due to insufficient fibrous tissue. For the same reason, long-healed wounds, including those from previous operations, can diverge (Fig. 1, 2) 2.

Atrophy of the glands of the hair root and epidermis is observed in 30–40% of dogs with HAC, which is likely due to the antiproliferative effect of glucocorticoids on fibroblasts with suppression of the synthesis of collagen and mucopolysaccharides. In humans, treatment local forms glucocorticoids reduce the synthesis of collagen types I and III; this may also be the case with HAC in dogs 2. Quite often these patients develop pyoderma, apparently due to multiple local skin changes and immune suppression from excess cortisol, which may be difficult to treat. In approximately 10% of cases of spontaneous HAC, demodicosis is detected that developed in adulthood. Specified inflammatory diseases skin, in turn, also prevent tissue regeneration 2.
It should also be remembered about secondary hyperparathyroidism, developing against the background of GAK. This pathology contributes to the activation of osteoclasts and, accordingly, osteodystrophy. A decrease in bone density and the process of its resorption prevent bone tissue regeneration during surgical interventions 2, 19.

Hyperandrogenism

Hypothyroidism in dogs

Pituitary dwarfism

Diabetes mellitus in dogs and cats

Results from a retrospective study of 45 diabetic dogs conducted between 1986 and 2000 suggest that most dermatological changes in diabetic dogs can be attributed to concomitant diseases. However, no skin disease directly related to diabetes mellitus. The most common pathology in dogs with diabetes was a superficial bacterial skin infection. Otitis is also a common finding in these patients. The manifestation of deep infections was often interdigital furunculosis 7, 14.

GAK cats

OKNs that secrete excess sex steroids

Feline hyperthyroidism

Obesity

Cellulite

TNF-α is a key component inflammatory process in obesity, which is expressed different cells, including macrophages, mast cells, neurons, fibroblasts and adipocytes 18. One of the main physiological effects of TNF-α is the induction of local insulin resistance. In this case, TNF-α suppresses the expression of genes responsible for insulin-dependent glucose consumption by cells 13 ; 15; 16 . In addition to inhibiting glucose transport into the cell, TNF-α reduces the uptake of free glucose by adipocytes. fatty acids and stimulates lipolysis and the release of free fatty acids into the systemic circulation 17 .

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