To date, conducting experiments involving animals is difficult due to the high cost, the complexity of reproducibility, as well as the ethical standards of modern society. The 3R concept developed in the last century encourages the development of alternative test systems. Among other alternative test systems, the wax moth larva occupies a special place. The use of larvae of the great wax moth (Galleria melonella) as a test system for determining the virulent properties of microorganisms is a promising direction and makes it possible to reduce the cost of research. However, not in all experiments, researchers could register the same semilethal doses for selected strains when comparing the Galleria melonella test system and mammals. Previously, a study was conducted, where, among other things, the semilethal doses of some strains were determined using the Galleria melonella test system. The aim of this study was to compare the semilethal doses of selected strains when administered to G. mellonella and mice. For the experiment, the animals were injected intraperitoneally with suspensions of reference strains of Escherichia coli ATCC 25922 (VKPM B - 8076), Staphylococcus aureus ATCC 29213, Streptococcus pneumoniae ATCC 6303 and clinical isolates of Escherichia coli ENV 194, Staphylococcus aureus SA 0077 (MRSA), Streptococcus pneumoniae 1068 19 A After infection, the animals were observed daily throughout the experiment. During daily clinical observation, visually noted (if any) clinical signs indicating the development of an infectious process, and also recorded body weight. After determining the LD50, the results were compared with the data obtained in the experiment with the larvae of the great wax moth. As a result of comparing the semi-lethal doses of the selected strains, it can be concluded that there is no clear correlation between the data obtained in the two experiments.

The purpose of the study was to study the features of the manifestation of the epizootic process during a returning infection in a fresh focus of brucellosis in cattle. The work was carried out on a dairy farm on a herd of cattle of a black-and-white breed, for a long time successful in brucellosis. The intensity of the epizootic process was assessed based on the results of serological studies of cattle of all sex and age groups. Immunological studies were carried out in accordance with regulatory documents on the diagnosis of brucellosis of animals. Standard diagnostic kits (S-) from commercial kits were used for serological studies in generally accepted reactions. Differentiation of positive and doubtful reactions was carried out using an experimental sample of an antigen made from brucella in R-form. A dynamic spread of brucellosis was noted during the six months with the 7% ill animals among all of the receptive cattle. Wellness measures were carried out with using the poorly agglutinogenic vaccine of strain Brucella abortus 82. The recovery period was 24 months. During of the trouble period 23% of infected animals were detected, including 19% of cows and 4% of young animals. The number of sick animals in a percent was estimated from the total numbers of the cattle in the farm. Based on the data obtained, it was established that under modern conditions, against the background of longterm well-being in a fresh focus of brucellosis, a dynamic spread of infection was noted with a wide coverage of susceptible livestock and a high intensity of the epizootic process.

This study examines approaches to assessing the risk of death and predicting the development of sepsis in dogs. Sepsis remains one of the key clinical problems in medicine and veterinary medicine, due to its widespread prevalence throughout the world, leading to high mortality. Sepsis is based on the reaction of systemic inflammation of the body, which is realized in the presence of signs of SIRS, bacteremia and/or an infectious focus of various nature in combination with acute signs of organ dysfunction and/or evidence of microbial dissemination. Since sepsis develops only progressively, it is impossible for the animal to recover independently without providing it with timely and appropriate medical care. Today, one of the key issues remains improving approaches to assessing the risk of death and predicting the development of sepsis in dogs. An attempt to combine the pathogenicity factors of an infectious agent and the failure of the host’s defense mechanisms is reflected in the concepts of PIRO, SAPS and MODS, which evaluate the links in the etiopathogenesis of sepsis. Thus, heuristic approaches will allow us to come closer to the development of pathogenetically based methods for assessing the risk of death of animals and predicting the development of sepsis in dogs. These approaches are based on criteria for assessing PIRO indicators: predisposition (P), including breed, sex, age of the animal; infection (I) associated with the type of pathogen detected; systemic response of the body to infection R, characterized by the main clinical indicators - body temperature, heart rate, respiratory rate and the number of leukocytes in the blood; organ dysfunction (O) identified in one or more organs of the animal. An important role in the objective prognosis is given to the evaluation criteria on the SAPS scale, taking into account changes in indicators towards hyperinflammation (SIRS) or immunosuppression (MODS), which determine the stage of development of sepsis and the likelihood of the risk of death of the sick animal. On average, the predictive accuracy of quantifying disease severity systems is 70–85%. An algorithm for translating clinical and laboratory data into a SAPS scale of indicators (scores) that determines the severity of the disease in leptospirosis in dogs is proposed. It has been shown that on the SAPS scale for canine leptospirosis, a score of 29

We have studied the impact of experimental staphylococcosis on the leukogram of Hisex Brown chickens. We divided the chicks into 3 groups, Group I assigned as control, Groups II and III – experimental. The chicks were challenged by intraperitoneal injection with Staphylococcus aureus (Group II) and Staphylococcus cohnii (Group III) at a concentration of 3 McFarland. The blood was drawn by cardiac puncture at days 1, 3, 5, 7, 9, 11 and 13 after the challenge. We studied the leukogram using stained blood smears. In the course of research we observed hematological parameters with lasting changes, which were more pronounced at days 1, 3, 5, 7 and 9 (in both experimental groups). We also observed an increase in the leukocyte count in the blood of chicks in Groups II and III, and a longterm pseudoeosinophilia along with monocytosis. We marked a decrease in the absolute lymphocyte count in both experimental groups, but the number returned to normal by the end of the experiment. The relative eosinophil count changed mostly in the blood of chicks in Group III, but the changes were insignificant. Basing on the data we have obtained during the experiment; we suggest that St. aureus exerts a toxic effect on the chicken organism in a greater degree than St. cohnii does.

Sheep pox and goat pox (GFP) and peste des petits ruminants (PPR) are infectious diseases of viral nature that mainly affect small ruminants. In domestic animals these are sheep and goats and in wildlife saigas, ibex, antelope and so on. These diseases are considered to be emergent infections, since they are characterized by a transboundary route of entry and spread, as well as causing enormous economic damage in small livestock due to almost 100% mortality and high lethality. Studies have shown that there is a high risk of introduction of emergent infectious diseases pathogens from the territory of West Kazakhstan region (through Kaztalovsky district) to Alexandrovo-Gaysky district of Saratov region. The risk is assessed as high, due to the fact that the largest number of susceptible small ruminants is concentrated on the territory of Kaztalovsky district, which amounts to 287640 heads. Small ruminants’ population density in this district was 15.5 heads/km2. The highest number of cattle is also observed on the territory of Kaztalovsky district (which is 117893 heads, which is of certain importance when keeping cattle and cattle together as a potential source-virus carrier of pathogens of the considered infections. Risk scoring, taking into account the criterion of availability of international routes of communication, showed 2 points out of 5. But, taking into account the fact that the interstate border is not marked and there is no control line, it entails the free movement of both wild and farm animals, in addition, the risk of uncontrolled movement and transportation of animals and livestock products through anthropogenic factor increases. Taking into account these facts, the risk can be assessed as 5 points out of 5.

Recently, geographic information systems (GIS) have reached a high level of commercialization, wide distribution around the world and are being introduced into various fields of science, including medicine and veterinary medicine in order to visualize geospatial information to improve the quality of epizootological and epidemiological monitoring. A geographic information system is a system that provides the collection, storage, processing, access, display and distribution of spatial data. Us from March 2020 to January 2023 work was carried out to study the frequency of occurrence of toxocariasis in dogs and cats in the city of St. Petersburg and the Leningrad region. Based on the results of the study of the helminth fauna of carnivores, as well as veterinary reporting data provided by the City Veterinary Department using the Quantum GIS (QGIS) program, data on the distribution of zoonotic invasion of carnivores were visualized and it was found that toxocariasis in dogs is more often recorded in Moscow (14.3 %), Frunzensky (10.2%), Nevsky (13.05%) Krasnoselsky (6.7%) districts of St. Petersburg and Vsevolozhsky (12.05%) district of the Leningrad region, and in cats - in the Kalininsky district (15 %), Nevsky (12.5%), Moskovsky (8.33%), Krasnoselsky (7.32%) and Admiralteysky (7.03%) districts of St. Petersburg. Thus, with the help of GIS, it is possible not only to systematize the spatial data obtained during research, which simplifies management and work with them, but also to visualize the data obtained in the form of digital maps, which in turn makes it possible to quickly and clearly assess the epizootic situation for a particular disease and as a consequence, improve measures of control and (or) prevention of invasion.

Every year a large number of animals are transported across the territory of the Russian Federation. In 2022, the movement of 156,229 heads of horses was recorded. To minimize the risks of spreading infections and invasions, strict veterinary requirements have been developed, including mandatory deworming during quarantine before shipment. The animals must arrive at their destination free of parasitic diseases. The study aimed to find out the possible risks of the spread of helminthiasis of horses with newly imported animals. Horses in transit through the city were examined. Blagoveshchensk from the farms of Central Russia to the country of East Asia. Feces were examined by flotation and larvoscopy methods, followed by determination of the systematic position of parasites. Helminthic invasion was detected in 64.3% of the examined animals with varying intensity. Both widespread helminthiasis of horses (trichonematosis, paraskaridosis) and dangerous diseases that are not registered in horses of equestrian clubs of Blagoveshchensk (alfortiosis, strongylosis, delafondiosis, anoplocephalidosis) have been identified. Taking into account the time of transportation, the duration of action of anthelmintic drugs in the body of horses and the timing of the preimaginal development of various types of helminths, the identification of these diseases indicates poor-quality deworming before transportation from the point of departure. When organizing the movement of horses, more careful control over the organization of the transportation process and compliance with regulatory requirements is needed to ensure the epizootic safety of animals, reduce the risks of spreading infections and invasions in safe territories.

In recent years, much attention has been paid in the Orenburg region to the issues of increasing fish stocks in natural and artificial reservoirs. Annually, the Ural River, reservoirs of the region are stocked with carp, sturgeon species of fish, as well as land reclamation activities. One of the reasons that worsen the quality of fish products from the reservoirs of the region is helminthiases. They reduce fatness and fat content, spoil the marketable appearance of caught fish, thereby causing significant economic damage [1].
Ligullosis is a common helminthic disease of many species of freshwater fish, especially often recorded in cyprinids. The disease in fish is caused by plerocercoids of Ligulidae from the genus Ligula (family Ligulidae). Parasitizing in the abdominal cavity, the helminth compresses the internal organs, disrupts their functions, which can lead to atrophy and infertility [2].
The natural causes of the spread of ligulosis include fish-eating birds - the final hosts of the Ligula. In the intestines of birds, helminths become sexually mature and live only a few days, standing out with litter and not causing much harm. It is quite difficult and not always possible to control the number of fish-eating birds in water bodies [3].
The aim of our research was to study the degree of infestation of bream with plerocercoids of the genus Ligula in the Chernovsky reservoir of the Orenburg region.

The theriofaunal list of wild bovids of the South-Eastern Altai includes the Altai mountain sheep (Ovis ammon ammon), as well as the Siberian mountain goat (Capra sibirica). The predominant types of farm animals in the Altai Republic are goats and sheep. Parasite fauna and the interchange between wild bovids and small cattle in these areas is not well understood. Samples were taken by employees of the Sailyugemsky National Park. At the department, V.L. Yakimov, ovoscopic and larvoscopic research methods were carried out. The calculation of the average number of eggs was carried out using a VIGIS counting chamber (VNIIP named after K.I. Skryabin). According to the results obtained, an analysis of cross-invasion was carried out. In wild bovids from 120 samples studied and in small cattle from 31 samples, endoparasites belonging to four large taxonomic groups were found: protists, trematodes, cestodes, and nematodes. In wild bovids from the group of nematodes, invasion with eggs of the genus Trichuris was established, according to morphological and morphometric characteristics, eggs of the ascarid type were found, eggs of nematodes of the order Strongylida, the genus Marshallagia, Nematodirella, Nematodirus spp., as well as larvae of the genus Protostrongylus were also found. From the group of trematodes, eggs of the species Hasstilesia ovis, as well as Dicrocoelium sp. From the group of cestodes, eggs of the genus Moniezia sp. From the group of protists, oocysts of the genus Eimeria spp. In small cattle, in contrast to wild bovids, nematodes of the genus Strongyloides sp. The number of cases of detection in small cattle of the nematode of the genus Protostrongylus sp. significantly lower than in wild bovids, and eggs of the strongylid type were more common. Also, no eggs of the trematode of the genus Dicrocoelium sp. Otherwise, the endoparasite fauna was similar to wild bovids. This study will help to compile a complete picture of the parasite fauna and cross-invasion of wild bovids and small cattle.

The purpose of the study is to establish the mechanisms of development of oxidative stress during long-term low-dose exposure to cypermethrin on the animal organism and to substantiate possible risks. The work was carried out using Wistar rats, which were intragastrically injected daily with cypermethrin at a dose of 1/1000 LD50 for 60 and 120 days. At the same time, control animals received an appropriate volume of saline solution inside. When removing animals from the experiment, blood was taken to determine the number of red blood cells, the concentration of hemoglobin, glucose, lactic and uric acids, and total bilirubin. In the study of erythrocytes and liver, biochemical parameters characterizing carbohydrate and purine metabolism, processes of xenobiotics biotransformation, pro- and antioxidant processes were determined. Long-term lowdose exposure to cypermethrin for 60 days causes hematotoxic effects in animals, enhancement of xenobiotic biotransformation processes, and slight compensatory restructuring of metabolic processes in the liver. Exposure to 1/1000 LD50 of cypermethrin for 120 days, in addition to the above effects, causes the development of acidosis, enhances pro-oxidant processes, and suppresses the function of the antioxidant defense system and the pentose cycle. The decrease in the activity of the liver antioxidant system is due to glutathione deficiency due to the activation of xenobiotic biotransformation systems and suppression of the activity of glutathione reductase and glucose-6- phosphate dehydrogenase, which ultimately leads to the development of oxidative stress. Long-term exposure of animals to low doses of cypermethrin causes hemolysis of erythrocytes, lactic acidosis, activation of prooxidant systems, and inhibition of the antioxidant defense system. Deficiency of carbohydrates and suppression of the activity of the pentose cycle indicate a decrease in the functional activity of the liver and an increased risk of immunosuppression.

The thyroid gland is very sensitive to various stress factors, including chemical ones. Meanwhile, the effect that many ecotoxicants have on the animal endocrine system has not been studied. The effect of cyanide-containing synthetic pyrethroids on the synthesis and secretion of thyroid hormones during prolonged low-dose exposure remains an open question. This research was aimed at assessing the morphofunctional state of the thyroid gland in laboratory rats under the specified exposure regime. The studies were conducted on 48 male Wistar rats. When modeling the effect of low doses of deltamethrin on animals, the substance was administered to rats at a dose of 1/100 LD50, and the experiment lasted for 120 days. The concentrations of thyroid-stimulating hormone, total thyroxine (T4), triiodothyronine (T3), and the ratio T4/T3 were determined in the rats' blood. The solid-phase enzyme immunoassay method was used to determine hormones. For histological examination, the thyroid gland of animals was fixed in a 4% neutral formaldehyde solution. Sections of paraffin blocks were stained with hematoxylin and eosin. Prolonged low-dose exposure to deltamethrin caused hypofunction of the thyroid gland in laboratory rats, which was accompanied by a decrease in the level of thyroid hormones in the blood serum. The stimulating effect of the pituitary gland increased compensatorily due to the additional release of thyroid-stimulating hormone. At the same time, there was a change in the ratio of T4/T3 in the blood. The histological patterns of the thyroid gland were characterized by a decrease in the thyrocyte area, growth of follicles, and colloid densification.

Liver pathologies have a significant impact on caffeine clearance, which deserves serious attention and research. In the case of liver pathologies, the processes of caffeine metabolism are significantly modified; however, according to the scientific literature, the vector of such transformations for specific pathologies has not been determined. This is due to the fact that hepatopathy reduces the activity of enzymes responsible for caffeine metabolism. In some cases, an increase in caffeine clearance may occur, which is associated with a temporary compensatory activation of certain enzymes that may be involved in caffeine metabolism. Also, the clearance of caffeine may be reduced due to a decrease in the metabolic activity of the liver, which will significantly slow down its final excretion.
To determine changes in the clearance of 1,3,7-trimethylxanthine, the most appropriate is to study its pharmacokinetic parameters, in particular, to compare its concentration in the blood serum in the phases of initial growth, plateau and decline with further construction of graphs - “caffeine curves”.
The purpose of the study was to determine changes in serum caffeine levels during the induction of toxic hepatitis.
The studies were carried out in the vivarium of the Department of Pharmacology and Toxicology of the Federal State Budgetary Educational Institution of Higher Education of St. Petersburg State University of Medicine.
In order to simulate toxic hepatitis, experimental animals were intragastrically injected with a 35% oil solution of carbon tetrachloride (CCl4) daily for 5 days at a dosage of 1.5 ml/kg. Upon completion of induction, toxic hepatitis was confirmed based on clinical and biochemical signs.
A day after the completion of the modeling of toxic hepatitis, the levels of caffeine in the blood serum were determined in the experimental animals in full accordance with the previous series of experiments.
As a result of the study, “caffeine” curves were constructed, indicating increased caffeine concentrations in serum, increased elimination time, as well as an extremely long plateau in the concentration of caffeine in the blood serum during toxic liver damage.

Feed antibiotics are widely used in the diet of poultry as growth stimulants, to maintain health and increase productivity. However, their use carries some risks, which leads to a reduction in the use of antibiotics in diets. Therefore, the search for an alternative that can minimize the negative effect of antibacterial substances is a global task. Plants containing phytochemical compounds are of great interest in the search. One of such phytobiotics is oak bark (Quercus cortex), some of its components act as agents of alternative antibacterial strategies (blocking of the Quorum Sensing signaling system (QS)). However, studies on the effects of Quercus cortex are few. It is interesting to study the additional effects of this phytobiotic in combination with other biologically active substances (probiotics, enzymes and antibiotics in small doses). Based on this, the purpose of this work was to evaluate the effect of Quercus cortex extract and Biovit 200 feed antibiotic based on 20% chlortetracycline on energy metabolism in broiler chickens.
The study was conducted using generally accepted methods of analyzing metabolic processes in the body of a bird. The calculation of net and exchange energies, energy protein ratio, coefficient of productive use of exchange energy, gross energy was made.
The results obtained allow us to conclude that the inclusion of Quercus cortex extract at a dosage of 0,2 ml/kg both independently and in combination with Biovit 200 at a dosage of 0,63 g/kg w.m./ day contributed to a reduction in the amount of energy loss with excrement with an increase in the KPI of OE and the compliance indicator, which shows a more rational use of energy for the process of tissue synthesis in the body of birds of I and III groups.

With the increase in consumer demand for fish products, the number of enterprises offering their products on the market has increased, which has led to a decrease in the quality of these goods. Cod liver is an expensive raw material for the production of canned food. In order to reduce production costs, manufacturers replace cod liver with salmon milk, in particular pink salmon, which is a species falsification. Modern methods of fish and fish products research are used to detect falsification in laboratory practice. The advantage of this method is that it is the most specific and sensitive for identifying the species of the raw material composition of the product and the finished product, since the DNA molecule does not lose its ability to perform an informative function under the influence of physical or chemical parameters, which characterizes it as the most stable structure of any animal organism. The research was carried out in the conditions of the Department of Molecular Research of the North-Western branch of the FGBI VNIIZH. The research material was 12 samples of canned fish sterilized from the liver of Atlantic cod. At the first stage, sample preparation was carried out by homogenizing samples into mortars, then 8 samples of each sample were taken, DNA extraction was carried out using a set of "GMO-Sorb-B". At the next stage, using the "Rotor-Gene 6000" amplifier, a polymerase chain reaction was set up, using kits for detecting the DNA of cod, haddock, pollock and DNA of salmon fish and differentiating species: pink salmon, chum salmon and sockeye salmon. As a result of the conducted studies, it was established that the liver of cod declared in the composition was not detected in one sample, since the content of cod fish was not detected in all samples from this sample, but the presence of pink salmon DNA was established. The results obtained indicate the specific falsification of canned cod liver.

The problem of radiation damage to the human body, animals, birds and its individual systems and organs against the background of the use of ionizing radiation sources has acquired relevance throughout the world over the past decades. In the event of an emergency, acute radiation damage in poultry will be massive and increase the risks of developing infectious and noninfectious diseases, due to a decrease in the level of specific resistance, low effectiveness of therapeutic and preventive measures and, as a result, will lead to a decrease in the quality of the resulting product. In view of this, studies aimed at studying the features of the course of radiation pathology in chickens are very relevant and will be taken into account when developing and applying radioprotective formulations.
The study of the features of the course of acute radiation damage caused by uniform single irradiation at doses of 7 Gy; 9 Gy; 11 Gy and 13 Gy, at a power of 0.99 Gy/min, was carried out on Leningrad calico chickens. Resistance to ionizing radiation was assessed by generally accepted clinical and hematological methods. Pronounced changes in clinical manifestations and shifts in morphological parameters of peripheral blood were noted under the influence of gamma radiation. Thus, irradiation of chickens with doses of 11 Gy and 13 Gy caused the development of acute radiation damage of an extremely severe degree, which led to severe depression, refusal of feed, shortening the duration or absence of a latent period, against the background of severe leuko- and erythropenia. Irradiation with a dose of 9 Gy caused severe acute radiation damage characterized by adynamia, reduced feed intake, diarrhea with an admixture of blood. Leukopenia was noted in the blood, which by day 12 values were lower than before irradiation by 41.9% and erythropenia. During acute radiation damage in chickens, when irradiated at a dose of 7 Gy, the development of the initial, latent, peak and recovery period in the surviving individuals was clearly traced. The clinical manifestation was characterized by a complex of dyspeptic and neuromotor disorders, moderate leukopenia was noted in the blood. In all experimental chickens, a violation of egg production was noted, up to complete cessation against the background of irradiation at doses of 11 Gy and 13 Gy. It is concluded that uniform single irradiation of chickens in doses from 7 Gy to 13 Gy leads to acute radiation damage and negatively affects the productive qualities of poultry. In order to conduct the experiment on the principle of pairs of analogues, 5 groups of animals were formed, 10 chickens in each. Determination of the content of erythrocytes, leukocytes and platelets in the blood was determined by counting in the Goryaev chamber. External total single exposure to gamma radiation at doses of 7 Gy, 9 Gy, 11 Gy and 13 Gy led to the development of acute radiation exposure of medium, severe and extremely severe degrees, respectively.

The article presents an analysis of the effectiveness of the immunostimulating effect of Echinacea purpurea extract and probiotic «Subtilis-C». The experimental part was carried out in two scientific and production experiments, in poultry houses with floor maintenance, on four similar groups of broiler chickens of the Cobb cross-500 with 100 heads each. To select an effective dose of Echinacea purpurea extract, the first scientific and production experience was conducted. The most optimal dose of Echinacea purpurea extract identified in the first scientific and production experiment was 5.5 mg/ kg of body weight. To evaluate the effectiveness of combining a plant extract with a probiotic, a second research and production experiment was conducted. Bactericidal and lysozyme activity in the blood serum of chickens. The paper provides data on the nature of the change in the level of the studied indicators in response to the introduction of Echinacea purpurea extract and probiotic «Subtilis-C» into the diet, the optimal dose and mode of combined administration of the studied preparations into the diet, composing the following scheme: Echinacea purpurea extract at a dose of 5.5 mg/kg body weight + «Subtilis-C» at a dose, pre-starter and starter feed (from birth to the age of one month) – 0.3 kg/ton, in finisher (from the age of one month to slaughter) – 0.15 kg/ton. In the established scheme, the plant preparation and probiotic effectively complement each other, which is significantly manifested by an increase in lysozyme activity of blood serum by 17.85%, and bactericidal activity of blood serum by 18.11%. It is noted that the established regime for the use of the studied evaporates contributes to improving the safety of livestock and the realization of the biological potential of meat productivity in broiler chickens.

Creation of domestic poultry crosses and development of optimal diets for them is an urgent problem, since in vivo studies using fistula technologies are currently few. The present work presents data on determination of duodenal and ileal activity of digestive enzymes when protein additives of vegetable (soybean meal and cake) and animal origin (fish meal and meat and bone meal) are used in the diet of laying hens. Experiments were performed on laying hens (Gallus gallus L.) of Hisex White cross (n=24, K.A. Timiryazev Russian State Agricultural Academy, 2022,2023) with chronic duodenal and ileal fistula. All chickens were divided by random sampling method into 4 groups: 1) 1 control group - received OR (Table 1); 2) 2 experimental group - 1.5% soybean cake was added to the diet instead of soybean meal; 3) 3 experimental group - 1.5% meat and bone meal was added to the diet instead of soybean meal; 4) 4 experimental group - 1.0% fish meal was added to the OR instead of soybean meal. It was found that protein additives are differently hydrolyzed in the intestine of birds and assimilated by the organism. Thus, the breakdown of soy protein is more intensive in cake than in meal due to the increase of trypsin activity in duodenum by 43.6%, and when fish meal is added, the activity of the enzyme increases by 11.8% against meat and bone meal and 101.5% against soy meal. At the same time, protein digestion increased, accompanied by an increase in trypsin activity in blood when soybean cake was used and in urine when fish meal was added to the diet of chickens. With feces the least loss of trypsin is observed in the group that received meat and bone meal supplementation (9.6% of trypsin activity is excreted), then fish meal - 16.8% and soy cake - 21.7% of activity in duodenum, which indicates the efficiency of exo- and endogenous protein utilization by poultry organism.

The southern waters of Lake Ladoga have important fishery significance - as a place for spawning, feeding and fishing. The hydrological features of this water area, combined with the location of sources of pollution, contributed to the creation of an increased level of anthropogenic load - massive toxicosis of fish and disruption of the process of natural reproduction, which was noted in the eighties of the last century.  
The period of early ontogenesis of fish is the most sensitive in the life cycle of fish, and this especially affects salmon and whitefish, which are especially sensitive to anthropogenic impacts, including toxicological factors.
As studies have shown, the impact of pollutants has also had a negative impact on other fish species whose spawning grounds are located in this water area. Recent ichthyopathological studies of fish in this water area, which includes three bays: Shlisselburgskaya, Volkhovskaya and Svirskaya, showed massive damage to fish by toxicosis, which prompted a study of early juvenile fish in the littoral areas of the bays. It was shown that in the surveyed water areas from 30 to 70% of early juveniles (larvae, fry) are affected by toxicosis with visual manifestations of the pathological process in the bone tissue, visual, circulatory system, etc. Typical anomalies are craniofacial defects, spinal anomalies, eye defects, of cardio-vascular system. It has been shown that the bone, circulatory, and visual systems are very sensitive to the effects of toxicants in the early stages. Population reproduction is an integral expression of the influence of the combined action of environmental factors and the fish organism itself.
The results of the studies showed a pronounced disruption of the natural reproduction of fish, which negatively affects the productivity of the reservoir. Preventive measures for fish reproduction are associated with the reclamation of polluted spawning grounds and factory reproduction of valuable fish species.
Typical anomalies are craniofacial defects, spinal anomalies, eye defects, and cardiovascular system defects. It has been shown that the bone, circulatory, and visual systems are very sensitive to the effects of toxicants in the early stages. Population reproduction is an integral expression of the influence of the combined action of environmental factors and the fish organism itself.

The economic efficiency of animal husbandry depends on the productivity of the herd, which is usually assessed by analyzing the reproductive performance of females. However, similar indicators of males should be equally taken into account. The accessory sex glands of males are involved in the production of seminal plasma, thereby playing an important role in the reproductive process. The aim of the study is to give a histomorphological characteristic of the accessory sex glands and to determine their functional state in newborn piglets. The object of the study was the accessory sex glands of newborn piglets at the age of 1 day. The vesicular and prostate glands were selected for histological examination. The material was fixed in a 10% solution of neutral formalin for 24 hours, after which it was poured into paraffin according to the generally accepted method. Then sections with a thickness of 3- 5 microns were made, which were stained with hematoxylin and eosin. Some of the sections were painted with Masson Trichrome, alcian blue. It was found that in newborn piglets, the vesicular gland is located on the dorsal surface of the bladder, at the beginning of the pelvic part of the urethra, the prostate gland is located caudally from the vesicular gland, dorsally from the genitourinary canal. The study established the main histomorphological features of the vesicular and prostate glands in newborn piglets. The parenchyma of the glands is in the stage of functional immaturity, most of the organ is occupied by the connective tissue stroma, among the elements of which there is a large number of fibroblastic cells. At the same time, secretory activity of some end sections of the vesicular gland is noted. The data obtained are the starting point for further studies of the functional activity of the cells of the accessory sex glands in boars.

The article presents skeletotopic landmarks of the points of fixation of the quadriceps femoral muscle in representatives of Canidae (shalayka and domestic dog), which are absent in the available literature.
Thus, it was revealed that the straight head in the distal part of the shalaika is attached to the base of the cranial surface of the kneecap by tendon fibers, and in the domestic dog its muscle-tendon fixation was found. The research was carried out at the Department of Anatomy and Histology of Animals named after Professor A. F. Klimov of the Moscow State Academy of Veterinary Medicine and Biotechnology – MBA named after K. I. Scriabin. The material for the research was sectional material - pelvic limbs (n=16), selected from adult dogs and canine hybrids (shalayka), without external signs of musculoskeletal system pathologies. The methods of fine macro- and microanatomic dissection under the control of a Micromed HR 350 S binocular magnifier were used, followed by functional analysis of the studied structures and skeletotopic projection of muscle attachment points on the kneecap. When studying the structures located on the kneecap, it was found that the cranial head of the tailor's muscle and the wide fascia of the thigh, covering the cranial surface of the kneecap, connects to the underlying organs through loose connective tissue. However, at the top of the cranial tubercle, they closely fuse with the tendon of the rectus femoris muscle, as well as directly with the periosteum of the cranial tubercle of the kneecap, and then, covering the rectus ligament of the kneecap, continue into the fascia of the lower leg.

Determination of the amino acid (AA) composition of cow milk, especially in terms of essential amino acids, is important and relevant. Recently, there has been an increase in publications on the improvement of methods for analyzing the AA composition of animal milk, primarily cows. The purpose of our research is to study the features of the amino acid composition of the milk of Black-and-White cows in the winter-spring period. The studies were carried out with samples of the “Ladozhskoye” breeding farm (Krasnodar Territory, Ust-Labinsky District). Group 1 (January) included 12 animals, groups 2 and 3 (March and April) included 22 animals each, i.e. a total of 56 animals. The cows were fed according to generally accepted norms. The determination of AA was carried out by ion-exchange chromatography with post-column derivatization of samples with ninhydrin on an LC-20 Prominence system (Shimadzu, Japan) and a column with an ion-exchange resin 4.6x150 mm (Sevko, Russia). New data on the AA composition of the milk of Black-and-White cows have been obtained. To author’s opinion, not only the absolute values of AA in milk are important, but also their ratios. For the first time, particular “rows” on the AA content in cow milk samples were obtained: Glu >> Leu > Lys = Pro > Asp > Val > Phe ≥ Ile ≥ Tyr > Arg = Ser > Ala = Thr ≥ His > Met > Gly > Cys (January) ; Glu >> Leu > Pro > Lys > Asp > Val > Phe > Arg ≥ Ile = Tyr ≥ Ser > Ala = Thr > His ≥ Met > Gly > Cys (March); Glu >> Leu > Pro > Lys = Arg > Asp > Val > Phe ≥ Ile ≥ Tyr > Ser > Ala ≥ Thr ≥ His ≥ Met > Gly > Cys (April). Our studies have shown a decrease in the AA amount of in cow's milk by spring (in March and, especially, in April), which can be explained by the adaptation of physiological and biochemical processes in the animal body during this period.

Protein-amino acid and fat composition of cow's milk are one of the important criteria for its evaluation. Although modern publications more and more mention the amino acid (AA) composition of cow's milk, especially for non-replaceable AAs, but in most cases, these works lack correlation coefficients between the main biochemical indicators (including amino acids), which reduces the value of such data. The purpose of this study is to identify correlations between the main biochemical parameters (with an emphasis on amino acids) of the milk of Blackand-White cows in the winter and spring seasons. The studies were carried out with samples of the Ladoga breeding farm (Krasnodar Territory, Ust-Labinsky District). Group 1 (January) included 12 cows, and groups 2, 3 and 4 (February, March and April, respectively) - 22 animals, respectively. The cows were fed according to generally accepted norms. The determination of AA was carried out by ion-exchange chromatography with post-column derivatization of samples with ninhydrin on an LC-20 Prominence system (Shimadzu, Japan) and a column with an ion-exchange resin 4.6x150 mm (Sevko, Russia). Data on the correlation coefficients between the AA of cow milk were obtained. There are practically no results of this kind in the literature. For all groups of the studied samples, positive correlation coefficients were found between the content of AA in the cow milk, mostly very strong (0.76-0.98), strong (0.51-0.75) and moderate (0.25-0.50). For the first time, correlation coefficients (from strong to moderate) between AA and cow milk proteins in the winter and spring seasons were obtained.

Mastopathy, as it is known, is one of the fundamental reasons for the decrease in dairy productivity of cows, sanitary and technological properties of milk, as well as premature culling of animals. The purpose of this study was to present a morphological justification of the risk of mastopathy in cattle. The research was carried out on the basis of the Department of Anatomy and Histology of Animals named after Professor Alexey Filipovich Klimov of the Moscow State Academy of Veterinary Medicine and Biotechnology – MBA named after K. I. Scriabin" and the breeding plant "Povadino" of the Moscow region. The object was Holstein cows. To conduct the study, an experimental group of animals (n=102) was selected from a herd of 1200 heads according to the principle of analogues, taking into account breed, body weight, age, number of lactations, reproduction index, which included clinically healthy animals (n=51, control) and experimental animals (n=51, mastitis). A comprehensive methodological approach was used, including a visual assessment of the state of the somatic systems of the animal body, macroscopic morphometry in order to determine the type of their constitution, the somatotype index and linear indicators of the mammary gland. Based on the conducted studies, anatomical and echographic parallels of the state of the mammary gland in the studied animals were established. In cows with mastitis, an increase in the circumference of the gland in comparison with the control group is accompanied by destructive changes in its excretory system in the form of massive fibrin overlays in the area of milk passages represented by heteroechogenic sites.The results obtained are basic in improving the methods of diagnosis and prevention of breast pathologies in cattle.

The aim of this work is to study the neuroinflammatory process in the epicardial adipose tissue (EAT) of the aorticpulmonary region of the rat heart during aging. The work was performed on Wistar rats aged 18-23 months (n=18). The adipose tissue of the pericardial region of rats was the object of study. Neuroimmunohistochemical markers (9.5 protein, tyrosine hydroxylase, synaptophysin) were used to study EAT innervation. The method of staining with toluidine blue and azure-eosin was used to study inflammation processes. Using histological and immunohistochemical methods, involutive and neurodegenerative changes in parasympathetic and sympathetic postganglionic nerve fibers were revealed in the white and brown adipose tissue of the heart of old rats (18-23 months old). A number of pathological changes were revealed in EAT: fibrosis, dystrophic changes and lysis of white adipocytes, disintegration of varicose axons of the terminal nerve plexus, as well as the formation of focal monocyticlymphoid infiltrates. It has been shown that the axons of the terminal nervous network are in close relationship with immune and inflammatory cells (lymphocytes, plasmablasts, monocyte-macrophage elements, mast cells). The noted morphological features indicate a neurogenic type of immune inflammation in the EAT of the heart. The identified changes may be the cause of chronic disorders of lipid metabolism during aging, leading to the development of pathological processes in the tissues of the main vessels of the aortic-pulmonary region of the heart, and also serve as prognostic indicators for clinical practice.

The African clary catfish is an exotic fish, so its breeding in our climate is carried out in closed water supply systems. The microbiota that is located in the gastrointestinal tract consists of various bacteria, and among them the most common are enterococci, lactobacilli, bifidobacteria, etc. They perform a number of functions, such as participation in digestion, synthesis of vitamins, preventing the proliferation of pathogenic microorganisms, etc. d.
The purpose of our work is to study the effect of dietary supplements on the degree of development and microstructure of the digestive canal organs of Clarias gariepinus fry. The material for the study was marbled catfish fry 30 and 60 days old, which were divided into three experimental groups according to the principle of analogue pairs. For a month after hatching, they were fed with food with the addition of a dry lyophilized culture of the Lactobacillus delbrueckii ssp complex. bulgaricus with Bifidobacterium lactis, as well as a probiotic with Enterococcus faecium. At the end of the experiment, histological studies of the digestive canal organs were carried out using our improved method.
The results of histological studies showed that, against the background of the use of probiotic feed additives of various compositions, changes in the structure of the wall of the esophagus and stomach of experimental fry are observed. In the epithelial plate of the esophageal wall, against the background of the use of a complex of lactoand bifidobacteria, the number of mucous and chloride cells visually increases. The degree of development of gastric glands after adding Enterococcus faecium to the feed is more pronounced by 30 days of age, and in 2-month-old fry their number is visually greater in fish using a complex of lactoand bifidobacteria. The study of the microstructure of organs proves that the use of these biological additives has a positive effect on the growth and development of the digestive tract organs of the African clariid catfish.

The entry of pollutants and nutrients in various ways (wastewater, aerogenic means and polluting surface runoff) had a negative impact on all parts of the cycle of substances in the reservoir. This was clearly shown by the results of a comprehensive study in the water system: lake. Ilmen - Volkhov river - lake. Ladozhskoye - r. Neva and Neva Bay, which especially affected the ichthyofauna of the studied reservoirs, both visually and during pathomorphological examination.
The southern waters of Lake Ladoga are of great fishery importance. More than half of the water area is occupied by the littoral zone - the shallow part of the lake, limited to a depth of 8.4 m. The hydrological features of this water area, combined with sources of pollution, form a high level of anthropogenic influence, which affects the condition of fish and their reproduction. Fishing was carried out in three water areas of the southern part of Lake Ladoga, in the littoral zone. For the study, they took the brain, gills, liver, kidneys, spleen, and gonads.
All studies of fish have shown massive toxicosis at the organismal level. A pathological and morphological study carried out at the cellular level confirmed the previously obtained results, revealing pathological changes in various organs. These changes are expressed in hemodynamic disturbances and various degenerative processes, including necrosis, which is the result of prolonged exposure to toxicological substances. On histological preparations, changes in the structural elements of gill tissue from petals to capillaries were observed.
The conducted studies showed, along with previously conducted pathological studies, their effectiveness in assessing the condition of fish. They also make it possible to assess both the quality of the fish habitat and the level of its pollution.

Reindeer are one of the most widespread and adapted representatives of the northern territories of the Arctic zone of the Russian Federation. Features of skeletal development are an important ontogenetic feature that reflects the level of development of the animal and the degree of realization of its genetic resource in the phenotype. The purpose of the presented research is to study the characteristics of the growth and development of the skeleton of the Nenets reindeer breed, taking into account the sex and age of the animals. Data were obtained on the peripheral and axial growth of skeletal bones from birth to the end of growth of males and females. Based on the studies conducted, it was possible to establish that in the postnatal period, the axial part of the skeleton of male and female reindeer grows faster than the peripheral part. Linear bone growth in deer ends earlier than weight growth. Females, compared to males, are characterized by more intense weight and linear growth of the skeleton, which confirms the relatively earlier completion of the growth and development of the body of females in relation to males of the same age. The growth rate of the reindeer skeleton is inferior to the rate of increase in live weight, which increases mainly due to the active growth of other tissues and organs. The greatest increase in skeletal mass and linear growth is observed during the milk period. Consequently, the first six months of a reindeer’s life are of great importance for the formation of physique, physiological precocity and the level of future meat and labor productivity. The revealed patterns of skeletal growth for reindeer of the Nenets breed do not exclude the possibility of extending them to reindeer of other breeds.

The purpose of this work was to analyze the prevalence of normal and pathological births in highly productive sows and the impact of their course on further reproductive function. The research was carried out in an industrial complex on 260 highly productive Yorkshire Landrace sows of Danish breeding. It was found that in highly productive sows in 32.69% of cases, pathological labor is recorded, including weak contractions and attempts - in 20.0% and manual labor – in 12.69%. With the clinical manifestation of weak labor activity in women in labor and with the provision of manual labor, 16.32% and 15.20% more piglets were received from them than during normal childbirth. At the same time, there is an increase in the duration of labor by 31.09% (p<0.001) and by 43.15% (p< 0.001), respectively. In pathological childbirth, women in labor are observed to breed more stillborn and mummified piglets than in normal childbirth. Providing obstetric care during childbirth increases the risk of developing inflammatory diseases of the uterus and breast in animals in the early postpartum period. The most common postpartum pathology with primary weakness of labor and manual labor is inflammation of the uterine mucosa, and with manual labor it is supplemented by an increase in the number of sick animals with postpartum dysgalactia.
In the next reproductive cycle, the sows, in which the physiological course of the birth process and weak contractions and attempts were recorded, had identical reproduction indicators. However, in animals that had a history of primary weakness of labor activity during the last birth, an increase in the unproductive period was recorded. In sows, after manual care, there is a violation and delay in the restoration of sexual cyclicity, a decrease in fertilization.

The study was conducted in order to study the polymorphism of the osteopontin gene (OPN) and to evaluate the indicators of milk productivity of Holstein first-calf cows with different genotypes. The work was carried out in the agricultural complex "Plemzavod im. Lenin" of the Atninsky district of the Republic of Tatarstan and the laboratory of the Department of Physiology, Biochemistry, Genetics and Animal Nutrition of the TatNIISKh FIT KAZNTS RAS. Genotyping was carried out by PCR-PDRF at the locus of the OPN-Bse1 I gene. The analysis of the genetic structure showed that the studied population is polymorphic by the OPN gene. The distribution of alleles and genotypes was as follows: C-0.432 and T0.568; CC – 14.3% (37 goals), CT - 57.8% (149 goals) and TT - 27.9% (72 goals). The highest milk yield for 305 days of lactation and a high yield of milk protein was observed in individuals with the CC genotype. During DNA testing of 258 Holstein firstcalf cows by PCR-PDRF of osteopontin gene polymorphism (OPN), it was revealed that the studied cattle population is polymorphic and is represented by all alleles and genotypes. According to the content of the mass fraction of fat and the yield of milk fat, a statistically significant superiority is observed in animals with a heterozygous CT genotype. It has been established that the C allele has a positive effect on the signs of milk productivity and the qualitative composition of milk.

In clinically healthy Holstein cows (n=25), the dynamics of hormonal metabolism in the first trimester of cow pregnancy was studied. For this purpose, the concentration of kisspeptin, 17β-estradiol, progesterone and cortisol was determined in the blood serum of cows. The animals were regularly monitored with clinical and obstetricgynecological studies. The level of kisspeptin in the first trimester of pregnancy increased almost throughout the entire period under consideration with a decrease in concentration to 194.23±23.61 pg/ml on day 98. The level of estradiol during the first trimester increased from 49.66±9.68 to 76.20±17.84 pg/ml, respectively, which is also explained by the inclusion of the fetoplacental complex in its synthesis and secretion. Progesterone and cortisol levels were on average at the same level. During the experiment, out of 25 animals, embryonic death was recorded in 14 on the 30th day after insemination. As a result, two groups were formed: the 1st group - animals with a normal course of pregnancy and the 2nd group with embryonic death. Analyzing the data of enzyme immunoassay in animals of the 1st group, one can note a decrease in the level of kisspeptin by 11% on the 28th day compared to the 14th day after insemination. At the same time, the concentration of estradiol, on the contrary, increased by 29%. In the second group, on the contrary, the level of kisspeptin and estradiol did not change and, on average, remained almost at the same level. On the 28th day after insemination in the first group, the cortisol concentration was significantly higher compared to the second group - 15.32±3.23 and 9.00±0.89 nmol/l, respectively. Data for kisspeptin and estradiol showed no significant differences. However, it is of interest that in the first group, with an increase in the level of estradiol, a decrease in the level of kisspeptin occurs. In particular, this is consistent with previous studies, according to which such an interaction of these hormones can be regulated by a high concentration of progesterone.

The preservation and use of frozen/ thawed male sperm is important for maintaining the biodiversity of poultry and will eventually play an important role in breeding, allowing greater flexibility in breeding programs. This use of thawed semen is advisable only at a high level of its fertilizing ability. Trehalose is a promising natural component in cryoprotective media for rooster semen due to its exceptional ability to neutralize cold stress. The purpose of the study was to determine the effectiveness of using trehalose as part of a medium for cryopreservation of rooster semen based on the Russian development - Leningrad cryoprotective medium (LCM-control). The composition of the LCM-T20 experimental medium with the addition of trehalose at a concentration of 9.5 mM has been developed. The mobility indicators of thawed rooster semen (Rhode Island Red breed, ♂n=10) did not differ significantly depending on the composition of the medium. Significant differences (p <0.05) were obtained in terms of egg fertilization: 86.0% when using the LCM-T20 medium and 79.0% using LCMcontrol and in assessing the state of the vitelline membrane of the egg yolk (p <0.001). The fertilization rate of eggs at a level acceptable for thawed semen of 50% was maintained until the 10th day (20th day of egg collection) from the last insemination when using the LKS-T20 medium. The functional usefulness of thawed sperm was maintained for 15 days (the 25th day of egg collection) from the last insemination when using the LCM-T20 media - egg fertilization was 15.0%, the average number of points of interaction of sperm with the vitelline membrane of the egg yolk was 345.2 pcs/cm2. When using the LCM-control diluent, the functional ability of thawed spermatozoa was absent during the same control periods. The achieved high level of egg fertilization when trehalose was included in the cryoprotective diluent in combination with the method of freezing rooster semen in pellets confirms the feasibility of introducing the LCMT20 diluent into the technology for preserving the genetic diversity of local and indigenous breeds of chickens using in vitro methods. 

The effect of polymorphism of the gene of the basic fibroblast growth factor (SNP11646 A/G) on the milk production of Holstein cows in the conditions of the Republic of Tatarstan was studied. The DNA of 270 full–aged cows was genotyped by PCR - PDRF. As a result, two FGFA – 0,591 and FGFG – 0,409 alleles were identified; and three FGFAA genotypes – 19,6% (53 goals) and FGFAG – 42,6% (115 goals), FGFGG – 37,8% (102 goals). The highest milk yield for full lactation and for 305 days of lactation, a high coefficient of lactation was noted in individuals with the genotype FGF2AG. The best milk quality indicators (high protein content, fewer somatic cells) were found in animals homozygous for the A allele. All cows have a high stable and smoothly decreasing lactation curve, the coefficient of lactation stability is higher for the GG genotype.

The aim of the research is to evaluate changes in the allelic structure of DNA microsatellites in a herd of Nenets reindeer. The work was carried out in the Priuralsky district of the Yamalo-Nenets Autonomous Okrug, on an experimental herd of animals belonging to the Yamal experimental station. The allelofund included a microsatellite profile of 300 deer obtained as a result of the 2018 study and 100 animals analyzed in 2022. It was found that significant transformations were observed at all loci, with the exception of NVHRT24. In the microsatellite profile of 2018, there were 6 alleles with a total frequency of 0.298, which were not detected in the 2022 studies. In 2022, 8 alleles with a total frequency of 0.105 not identified in the previous study were established. The Shannon index indicates a slight increase in genetic diversity in the analyzed population (by 0.059), as well as an increase in the observed heterozygosity of animals (by 0.074). The fixation index for all analyzed loci showed that both in the sample of 2018 and 2022, there was a deficit of heterozygotes in the study population, however, the data of 2022 indicate a decrease in the deficit of heterozygotes by 0.089. Analysis of the divergence of the population for individual loci indicates that the maximum divergence of the allelic structure occurred at the RT9 locus (d=0.331), RT30 (d=0.236) and NVHRT76 (d=0.231), and the maximum similarity was preserved for the loci NVHRT24 (d=0.007), RT1 (d=0.0014) and RT7 (d=0.0020). Thus, pronounced gene drift was observed in the studied population.

Currently, three groups of scientists are developing the introduction and use of lowfrequency ultrasound in retinal and vitreous surgery. There is not enough data and work to study the effects of this type of energy on the functional activity and structural state of the retina. In this regard, we conducted experimental and diagnostic studies using modern and objective methods. The main purpose of this article is analyzing the parameters of the electroretinogram of the rabbit retina and compare it with histological data after removal of the vitreous body using low-frequency ultrasound and mechanical action. Experiments were conducted on Chinchilla rabbits (n=40). In the experimental group (n=20), vitreous removal was performed using low-frequency ultrasound, in the control group (n=20) using a guillotine mechanism. On the 1st, 7th, 14th and 14th days, the parameters of the a- and b-waves of the electroretinogram were recorded. The structural state of the retina was also evaluated on histological sections. On the 1st day after surgery in both study groups there was a decrease in all parameters of the electroretinogram, the evaluation of histological data showed the presence of edema in most layers of the retina. On days 7 and 14, the parameters of the a- and b-waves were restored, but did not return to normal in both groups, a decrease in edema in all layers of the retina was observed on histological preparations. On day 30, the a- and b-wave indicators returned to normal, which indicates the restoration of the functional properties of photoreceptor cells, bipolar and Muller cells in both groups, the retinal layers were clearly visualized on histological sections without signs of edema. Analysis of electroretinogram parameters and histological data showed that the use of low-frequency ultrasound for vitreous removal can be considered safe and promising for further development.

Gastrointestinal diseases in horses are one of the most common causes of death among sport horses. Volvulus of the large colon is one of the most severe forms of diseases of the gastrointestinal tract of horses. The disease is acute and requires immediate hospitalization and surgical intervention. With complete volvulus of the large colon, in the absence of surgical treatment, death occurs in 100 percent of cases.
The limited number and inaccessibility of specialized clinics capable of performing this operation make the problem of prevention, as well as timely detection and treatment of concomitant diseases that can provoke volvulus of the large colon, urgent.
In this article, we analyzed the literature data on this issue, and also present our own statistics obtained during the collection of anamneses from patients operated on in our clinic in the period 2021-2023, with a diagnosis of volvulus of the large colon.
The main reasons that can provoke volvulus of the large colon can be considered gross violations in the technology of feeding and keeping horses, lack of conditions for daily exercise, the use of medications, the side effects of which can be inflammatory processes in the gastrointestinal tract, lack of control over the condition of teeth, recent foaling in mares.
During the period 2021-2023, twelve patients diagnosed with volvulus of the large colon were operated on in our clinic. Six of these were mares, one arrived three weeks after foaling, five were geldings aged 7, 10, 16 and 19 years and one was a stallion.

Modern technologies of industrial animal husbandry imply the most effective use of the reproductive potential of females and obtaining healthy young from them. The limiting factor in achieving this goal are diseases characterized by smoothed symptoms, which complicates their timely diagnosis and therapy, one of which is genital mycoplasmosis of cattle. The presence of a long latent period and unclear symptoms allows this disease to remain unnoticed and spread in the herd. During the latent period, morphofunctional changes develop in the body of females, leading to partial or complete loss of reproductive ability. Tetracycline, fluoroquinolone and macrolide antibiotics have been used with varying degrees of effectiveness for the treatment of cows with genital mycoplasmosis, however, antibiotic therapy alone does not restore all functions disrupted during the disease, and in particular does not eliminate immunodeficiency. In this regard, the purpose of our study was to study the inclusion of the immunomodulator thymalin in the treatment regimen of cows with genital mycoplasmosis and its effect on the content of leukocytes, lymphocytes and their subpopulations in the blood. Three groups of animals were formed for the experiment: the first group - pregnant cows with genital mycoplasmosis for the treatment of which the antibiotic traksovet 100 (tulatromycin) was used at a dose of 2.5 mg per 1 kg of animal body weight, subcutaneously, once 40 days before the expected delivery; the second group - pregnant cows with genital mycoplasmosis for the treatment of which the antibiotic traksovet 100 was used at the same dose and the immunomodulator timalin at a dose of 0.1 mg per 1 kg of animal body weight, intramuscularly, twice with an interval of 72 hours; the third group – clinically healthy pregnant cows. In all groups of cows, the number of leukocytes, the percentage of lymphocytes, the absolute and relative content of T-, B- and 0-lymphocytes were determined. It has been established that the use of tulatromycin for the treatment of cows with genital mycoplasmosis gives a good therapeutic effect, but provides only partial restoration of cellular immunity. The combined use of tulatromycin and thymalin has the maximum therapeutic effect and leads to the complete restoration of cellular immunity, and some indicators even slightly exceed their value in clinically healthy cows.