Introduction. The contact point between an astrocyte and a chemical synapse is the location of the signaling and transport processes that play an important role in functioning of the nervous system and in neurological diseases pathogenesis of humans and animals. The goal of the study was to investigate the correlation between the average size of the active zone of the synapse and the frequency of synapse-astrocyte contact formation in the cerebral cortex layers of rats.
Materials and methods. The 40 μm frontal sections of the primary somatosensory cortex of 5 outbred male white rats were taken as the material for the study. Astrocytes were labelled for Transmission Electron Microscopy (TEM) by incubation of the tissue sections with primary antibodies to the s100β protein and with horseradish peroxide-conjugated secondary antibodies, followed by the development of the label in the reaction with DAB. For each layer, 250 images were obtained at 25,000х magnification. On the images the length of the synaptic cleft was measured and the number of synapses forming contact with the astrocyte membrane was counted.
Results. The value of the fraction of the chemical synapses forming contact with the astrocyte membrane in the primary somatosensory cerebral cortex of rats demonstrated the direct correlation with the average length of the synaptic cleft only in the first to fourth layers. Thus, in the first layer, the value of the fraction of synapses forming contact with the astrocyte was the smallest (PI = 0.27 ± 0.1), as was the length of the synaptic cleft (lI = 329.45 ± 10.45). When moving deeper into the cortex, the fraction of synapses forming contact with the astrocyte and the length of the synaptic cleft increased from the second (PII = 0.48 ± 0.11 and lII = 363.64 ± 11.14) to the third layer (PIII = 0.69 ± 0.09 and lIII = 382.27 ± 9.81), followed by the decrease of both values in the fourth layer (PIV = 0.53 ± 0.09 and lIV = 355.2 ± 8.12). In the fifth layer, the fraction of synapses forming contact with the astrocyte sharply increased again (PV = 0.68 ± 0.08), which, however, was not accompanied by the proportional increase of the average length of the synaptic cleft (lV = 350.79 ± 7.82). At the same time, in the sixth layer of the cortex, on the contrary, the sharp increase in the average length of the synaptic cleft (lVI = 396.03 ± 10.77) was observed, reaching the maximum value through the cortex, with low, compared to other layers, fraction of synapses forming contact with the astrocyte (PVI = 0.44 ± 0.09). Thus, it turned out that the fraction of synapses forming contact with the astrocytic membrane is more related to the density of the astrocytic membranes in the layer (the research we published earlier), rather than to the average length of the synaptic cleft. Discussion and conclusions. The obtained results substantiate that the contact is formed as a result of a combination of random membranes encounter followed by the selective anchoring or repulsion of the astrocyte membrane under the influence of various factors, only partly determined by the size of the chemical synapse.

Introduction. Aiming to study the literature sources referring to evolvement of the veterinary medicine into a science in Portugal of the XIV–XVIII centuries, the article presents the detailed description of the historical materials (books, works, records) existing and being kept in libraries and archives.
Materials and methods. The materials taken for the study were literature sources and archival materials in Portuguese and Spanish. The data obtained during the research was structured, arranged in the chronological order of events and analysed.
Results. The veterinary medicine of the country almost completely depended on historical events and cultural trends. Until the XVII century, due to the popularity of falconry, only the knowledge of horses and birds of prey anatomy and diseases received the noticeable development, whereas the literature sources on other animal species anatomy and diseases appeared only at the beginning of the XVIII century.
Discussion and conclusions. The study of the materials leads to the conclusion that the history of the Portuguese veterinary medicine and its documentation in the literature sources were inextricably related to the historical events that took place in the country – the political and economic factors, as well as popular trends, had influenced the evolvement of the veterinary science and the amount of publications.

Introduction. One of the diseases most frequently occurring in the representatives of the feline family (Felidae) is feline panleukopenia. Feline panleukopenia is a highly contagious disease of viral etiology with high (up to 90%) mortality. It affects representatives of the feline as well as the raccoon (Procyonidae) and the kunih (Mustelidae) families.Despite the preventive measures taken, the virus continues to circulate actively in the population of susceptible animals.
The aim of the work is to analyse the epizootic situation and to review the domestic and foreign scientific publications.
Materials and methods. The data obtained from the record books of a number of veterinary clinics of the cities of Ivanovo and Vladimir on the primary veterinary outpatient visits of sick animals within the period from 2020 to 2022 has become the subject of the research. Additionally, the brief description of feline panleukopenia and the epizootological data referring to the various cities of the Russian Federation available in the similar publications for the period from 2012 to 2022 is provided in the article. The data from the foreign sources on seasonal manifestation of the disease is also presented.
Results. The analysis of the feline panleukopenia epizootic situation in the certain districts of the cities of Ivanovo and Vladimir has been carried out. The data on the panleukopenia permanently adverse situation in a number of the Russian Federation cities has been obtained, its share among other nosological units in cats reaches 3.6-27%. The data analysis results for the Russian cities located in the various federal districts, as well as for the cities of Ivanovo and Vladimir, has shown that the feline panleukopenia cases detection throughout the country is subject to seasonality, the peaks of cases detection fall on spring-autumn. It has also been confirmed that the main age group susceptible to panleukopenia includes kittens under the age of one year (3-6 months old). The need for more comprehensive understanding of the disease epizootic situation is pointed out as well as the need for phylogenetic studies of the new feline panleukopenia virus isolates which would enable carrying out the efficient preventive measures.
Discussion and conclusions. Understanding the real epizootic situation in the Russian Federation regions and obtaining the new isolates of the feline panleukopenia virus for diagnostic, production and control purposes will make it possible to determine more efficient measures for combating this infection.

Introduction. Urbanisation of territories creates a critical risk related to contagious animal diseases. The agro-industrial complex (AIC) of the Northwestern region is an important component of the food security system of the Russian Federation. The research is aimed at studying and defining the degree of epizootic risk of contagious animal diseases in the region, determining the degree of epizootic threat thereof at the population and interpopulation levels.
Materials and methods. For conducting the study the comprehensive epizootological approach (analysis) was used, along with the methods of evidence-based epizootology, epizootological diagnostics, methods of modern prognostics and statistical methods of quality control.
Results. Functioning of infectious parasitic systems have been studied under specific conditions of place and time, using digitalisation achievements and statistical quality control. The epizootological categories have been proposed and applied for the three-dimensional measurement of the epizootic manifestation of contagious diseases using the corresponding units for their mathematical measurement (indicator of ill-being, epizootic index, incidence and prevalence, pathogenicity spectrum, frequency, recurrence, seasonal epizootic growth and year-round disease incidence). All the above allows carrying out the epizootic supervision over the formation and functioning of separate nosological units in animal populations under specific conditions of place and time. Using the comprehensive epizootological approach and the evidence-based epizootological methodology, the degree of epizootic risk of contagious animal (bird) diseases in the agro-industrial complex of the Northwestern region was studied in relation to the various economic and technological levels of animal husbandry and the degree of territory urbanisation.
Discussion and conclusions. It has been found that in the agro-industrial complex of the metropolis suburban area of the Northwestern region, there have formed and periodically appear 45 animal diseases, predominantly of infectious etiology (62.2 %). The different degree of diseases epizootic risk was revealed: from its absence, in case of 4 nosological units, up to high and very high degree, in case of 15 nosological units (33.3 % of the total number). Therefore, the purpose of the present work was to study the degree of the risk of infectious diseases potential occurrence in populations of production animals in various areas of the Northwestern region and to identify the cause-andeffect indicators underlying the differences.

Introduction. Ixodid ticks are the carriers of many infectious and parasitic diseases. Transmissible tick-borne diseases include borreliosis, viral encephalitis, anaplasmosis, ehrlichiosis and babesiosis, they can be dangerous for both humans and animals. Since the forest areas stopped being treated with pesticides, the reproduction of ixodid ticks became almost unregulated, and their population is constantly growing. In addition, ixodid ticks, the carriers of a number of dangerous anthropozoonosis, have high fecundity.
Therefore, the aim of the study was to investigate the process of ectoparasites development, specifically, the dynamics of the oocytes maturation process in ixodid ticks of the genus Dermacentor. Materials and methods. The ixodid ticks of the genus Dermacentor were the object of the study. The study was conducted on the basis of the Chair “Parasitology and Veterinary-Sanitary Expertise, Anatomy and Pathoanatomy named after Prof. S. N. Nikolsky” and the Scientific-Diagnostic and Medical Veterinary Center of the Federal State Budgetary Educational Institution of Higher Education "Stavropol State Agrarian University", as well as on the basis of veterinary clinics "Veterinary Center named after Pirogov” of the individual entrepreneur Zaichenko. The reproductive system of females served the material for the research. The females were treated and filled into paraffin according to the routine histological technique, afterwards the sections of 5-7 µm. thick were made. For routine examination, histological sections were stained with hematoxylin and eosin, as well as by Mallory staining method. Microscopic examination of the histological sections of female ticks was carried out using the Olympus BX53 microscope (Japan) at 4×, 20×, 40×, 100× magnification.
Results. The macroscopic examination of female ixodid ticks of the genus Dermacentor showed that ovary is an azygos, horseshoe-shaped organ to which oocytes are attached. It was observed that oocytes develop asynchronously. Immature oocytes predominated mostly in the distal part of the ovary, while mature — in the proximal. The oocytes of this species of tick are classified by five main stages of maturation and are described based on the cytoplasm external view, the presence of the germinal vesicle, the presence of yolk granules and the chorion formation, and the morphometric data. The process of oocytes maturation at different stages is not linear. During vitellogenesis, the active and verified dynamics of growth is recorded from I to V stage of oocytes development the increase of their size by 55 times is observed.
Discussion and conclusions. In female ticks of the genus Dermacentor, maturation of oocytes goes through 5 stages. The process of oocytes maturation at different stages is not linear, since both mitotic and meiotic processes occur simultaneously in the ovary. At the same time, in the oocytes development the active verified dynamics of growth is recorded.

Introduction. On the territory of the North Caucasus Federal District, the most popular duck breeds at farm enterprises are Temp and Chernaya Belogrudnaya. They are fast growing, resistant to diseases and cold. Tetramerosis is a seasonal helminthic disease of ducks. At the same time, the epizootological features of tetramerosis infestation in domestic ducks are poorly studied from both fundamental and applied sides of the problem.
The aim of the study was to investigate the tetramerosis infestation epizootological features and occurrence in the populations of domestic ducks of zoned breeds in the North Caucasus region (in the conditions of the Kabardino-Balkarian Republic).
Materials and methods. Conventional methods of parasitological studies were used in the work: the method of complete helminthological dissection (СHD), determination of the infestation intensity and extensity. The results were statistically processed using the “Biometrics” software.
Results. Tetramerosis infestation extensity (IE) in ducks of the breeds Temp and Chernaya Belogrudnaya in the context of natural areas of climatic zones of the Kabardino-Balkarian Republic (according to the data of the СHD of ducks glandular stomach and fundus glands) is manifested with different quantitative values covering most of the free-range growing birds of both breeds aged from 1 up to 6 months old. In the context of all natural and climatic zones, the extensity of tetramerosis infestation in ducks of the Chernaya Belogrudnaya breed was relatively higher than that of the Temp breed by 10.67 % in average. The activeness of the tetramerosis enzootic manifestation in ducks of the Temp breed: in the plain belt IE — 20.0 %; in the foothills — 30.0 %; in the mountain belt — 16.0 %. The average tetramerosis IE in ducks of the Temp breed was 22.00 ± 1.36 %. The tetramerosis infestation extensity in ducks of the Chernaya Belogrudnaya breed was: in the plain belt — 32.0 %; in the foothills — 42.0 %; in the mountain belt — 24.0 %. The average tetramerosis IE in the ducks of the Chernaya Belogrudnaya breed was 32.67 ± 1.83 %, which indicates a greater susceptibility to infestation. Upon the analysis of the glandular stomach and fundus glands dissection results of domestic ducks of the Temp and the Chernaya Belogrudnaya breeds in the natural and climatic zones of the Kabardino-Balkarian Republic it was also found that this infestation is manifested with extremely high rates of infestation intensity (II). Tetramerosis in domestic ducks of the Temp breed: in the plain belt was recorded with II — 18.3 ± 1.28 eggs/specimen; in the foothills — 25.7 ± 1.40 eggs/specimen; in the mountain belt — 15.9 ± 1.13 eggs/specimen. The average tetramerosis II in domestic ducks of the Temp breed was 19.97 ± 1.27 eggs/specimen. In domestic ducks of the Chernaya Belogrudnaya breed, the tetramerosis occured: in the plain belt with II 26.8 ± 1.73 eggs/ specimen; in the foothills — 33.4 ± 1.95 eggs/specimen; in the mountain belt — 21.2 ± 1.58 eggs/specimen. The average tetramerosis II in ducks of the Chernaya Belogrudnaya breed was 27.1 eggs/specimen.
Discussion and conclusions. The rates of tetramerosis extensity and intensity in the ducks of the Chernaya Belogrudnaya breed tended to increase in domestic ducks of the age 1 to 6 months old. In subsequent age groups, the infestation was decreasing, which should be taken into account when determining the timing and frequency of dehelmintization.

Introduction. Parasitic diseases are one of the main problems of horse breeding, in particular, helminthic infestations. The helminths are able to induce mechanical, toxic, inoculation effect. Moreover they absorb the nutrients necessary for the horse body. Thereby the helminths inflict significant harm on the horse population, not only due to animals deaths, but also due to weakening the protective functions of the body as well as working capability, sports and breeding qualities of horses. The aim of the present work is to study the epizootological aspects of helminthiases in horses at the territory of Tyumen region.
Materials and methods. The study was carried out taking into account the horses keeping and care practices in twenty-two administrative districts of the region, located in the subzones of the northern and southern forest-and-steppe and subtaiga areas. To determine the infestation extensity (IE), the parasitological research methods of Kotelnikov-Khrenov, Fülleborn’s, Darling's modification method and the method of studying the scrapings of the perianal folds of the horse were applied. Results. During the research it has been found that the infestation extensity in horses infested with helminths in the Tyumen region averages to 27.9 ± 1.43 %. Whereas, the maximum helminthic infestation was found in horses in the subzone of the northern forest-and-steppe area IE 38.7 ± 1.97 % and the minimum in the subzone of the southern forest-and-steppe area IE 22.5 ± 1.16 %. It was found that in the conditions of year-round keeping in the stables with regular walking, the intestinal helminths parasitised in horses with the following infestation extensity (IE): Parascaris equorum 70.1 ± 2.53 %, suborder Strongylata 48.3 ± 1.97 %, Oxyuris equi 36.1 ± 1.63 %, the representative of Strongyloides westeri 20.9 ± 1.19 %. In the conditions of herd farming, the maximum infestation extensity in horses was observed for the helminths of suborder Strongylata with IE 74.0 ± 2.31 %, also spotted were parasites Parascaris equorum with IE of 41.2 ± 1.67 %, Oxyuris equi with IE — of 13.2 ± 0.87 % and the minimum infestation extensity was recorded for the parasites Strongyloides westeri with IE of 6.5 ± 0.21 %. In horses in the conditions of improved herd farming, the maximum infestation extensity was observed for the helminths of suborder Strongylata with IE of 79.4 ± 2.52 % and the minimum was for Strongyloides westeri with IE of 0.8 ± %. When studying the distribution of infestation in relation to the keeping and care practices, the data was obtained confirming that under practices of keeping in stables the helminths Parascaris equorum prevail with IE of 70.1 ± 2.53 % and under practices of herd and improved-herd farming the helminths of the suborder Strongylata with IE of 74.0 ± 2.31 % and IE 79.4 ± 2.52 %, respectively.
Discussion and conclusions. Thus, in the result of studying the epizootic aspects of helminthiases in horses, it was found that helminthic infestation is recorded in various climatic zones throughout the whole territory of Tyumen region.

Introduction. Among the animal infestations, a large number of zooanthroponoses have been identified. Therefore, it is necessary to study the mechanisms of helminthiases behaviour and to constantly monitor the helminth fauna in animals that have close contact with humans.
The work aimed at studying the age-related features of dogs infestations in the plains of Dagestan, including studying the presence of specific types of helminths. The main attention was paid to the influence of environmental factors and dogs’ lifestyle on the helminthic infestations prevalence and intensity in different age groups.
Materials and methods. Age dynamics of helminthic infestation was studied in domestic dogs that were in self-walking and in stray dogs of different ages and sexes. Dogs were divided into three categories: of age 1–6 months old (puppies), of age 1–2 years old (juvenile animals) and adult specimens. In the work the method of animal and human complete helminthological dissection was used, as well as some other methods, such as sequential washing, flotation with the use of saturated solution of ammonium nitrate, Berman-Orlov method of larvoscopy and methods of examinations used in sanitary helminthology.
Results. The results show that puppies are infested with 5 types of helminths out of 19 identified in dogs with probability of up to 40 % and the infestation intensity of up to 72 items. In general, infestation rates in puppies were low. The highest prevalence was observed for E. granulosus with infestation extensity 10.0 % and the infestation intensity varying from 12 to 72 items. T. canis also had a high prevalence rate of 40.0 % with infestation intensity from 7 to 19 items. On the other hand, T. hydatigena and A. caninum had the lowest prevalence rate of 6.6 % with infestation intensity from 3 to 12 items. It was found that juvenile animals of 1-2 years old and adult dogs were infested with 12 different types of helminths. It should be emphasized that dogs aged 1-2 years old were especially susceptible to infestation at this stage. In total, six different types of helminths were identified with the high prevalence rate (ranging from 26.6 to 53.3 %) and infestation intensity (from 7 to 109 items). Indicators of the infestation intensity and extensity were higher in dogs infested with E. granulosus and T. canis namely IE 40.0 % and II 21 to 109 items for first species, and 53.34 % and 11–61 items for second species. Helminthiases found in adult dogs were similar to those found in juvenile animals aged 1 to 2 years old, but with a lower degree of infestation. The highest infestation extensity and the highest infestation intensity was observed for E. granulosus and T. canis, respectively – 26.6 %, and 4–16 items. On the other hand, the lower rates were observed for M. xanthosomus, A. alata, D. immitis and T. mystax, with IE 6.6 % and II 1–9 items. It was found that in comparison with juvenile animals, adult dogs are much less likely to be infested with helminths, and this is most likely due to the formation of the age-related immunity.
Discussion and conclusions. It was found that the character of helminthic infestations in dogs, depending on their age, is influenced by the changes in natural and climatic conditions, environmental factors and animals keeping and care practices.

Introduction. Currently, keeping the small pets, in particular cats and dogs, is becoming more and more popular every year. Unfortunately, not all the breeders are familiar with the rules of care, feeding, keeping, breeding and first aid provision during the parturitions. Thus there occur cases of the pathological patrimonial activity, which can subsequently lead to uterine prolapse in animals. Another important reason causing pathology is keeping animals in the self-walking. This leads to uncontrolled mating of animals of various breeds and weight categories and most often causes macrocarpous pregnancies in females.
The aim of the study is to make the comparative evaluation of the surgical methods of uterine prolapse treatment in cats and dogs, whereas the pathology itself is much less common than other reproductive diseases and has not been sufficiently studied.
Materials and methods. The study was carried out from 2021 to 2022 at the Chair of Non-Contagious Diseases of Agricultural Animals of the Federal State Budgetary Educational Institution of Higher Education “Northern Trans-Ural State Agricultural University” and at the premises of the veterinary clinic “Polar Bear” of the town of Yalutorovsk. The objects of the study were cats and dogs of different breeds and ages admitted to the clinic. During the study, the clinical, biochemical methods and the anamnesis data were used.
Results. Within the period from 2021 to 2022 the number of pet owners attending the clinic was 6179. Of these, 2505 (40.5 %) were admitted with dogs, 3593 (58.1 %) with cats and 81 (1.3 %) with other animals. Among cats and dogs 4345 females were registered, their share equaled to 71.3 %, of which 2816 (46.2 %) were cats and 1529 (25.1 %) were dogs. The share of reproductive diseases in cats accounted for 683 cases out of 2816 (24.3 %), in dogs – 389 cases out of 1529 (25.4 %). It was found that uterine prolapse in cats accounts for 1.8 %, and in dogs for 3.3%. It was also revealed that the pathology occurs in cats aged 3 to 6 years old (50.0 %), in dogs under the age of 12 months old (46.2 %), due to the onset of the first estrus, and in animals older than 7 years old (53.9 %) due to multiple parturitions. In terms of breed susceptibility among cats the pathology was most often found in outbred specimens (50.0 %).
Discussion and conclusions. The efficiency of treatment during the reposition of prolapsed uterus in the first group of animals was 30 %; this leads to the conclusion that the risk of relapse is very high and that the ovariohysterectomy is recommended for this pathology.

Introduction. In fur farming, there arise problems negatively effecting quality of the end products. One of them is malnutrition. Therefore, the researchers are studying the diets composition of furbearing animals and the possibility of using feed additives. However, very little attention is paid to the effect they have on the morphological structures of internal organs, in particular, the organs of the gastrointestinal tract.
The aim of the research was to study the small intestine morphometric parameters when using the biologically active additive "Emprobio" at different periods of ontogenesis.
Materials and methods. The small intestine of the minks of different age groups: newborns, two-, fourand eight-month-olds was the object of the study. To study the morphometric parameters, the macroand micromorphometric methods were used.
Results. The relative thickness of the small intestine mucous membrane to the total thickness of the intestinal wall in minks at birth was 60.4 %. By the age of two months old, it increased by 0.9% in the experiment group and on the contrary decreased by 2.1 % in the control one. At the age of 2–4 months old, this parameter increased to 61.3% in the experiment group and to 58.3 % in the control group. At the age of 4–8 months old, it decreased in both groups, but by the end of the experiment it increased by 2.7 % in the experiment group, by 0.5 % in the control one. By the age of two months old the height and diameter of the glands have slightly and equally increased in both groups. At the age of 2–4 months old, the height of the glands increased to the maximum: by 5.1 times in the experiment group and by 4.7 times in the control one. In the same period, the decrease of glands diameter growth rate was observed, the diameter increased only by 1.6 times in both groups. At the age of 4–8 months old, the growth rate of the glands height and diameter slowed down even more in both groups: the height increased by 1.3 times, the diameter by 1.1 times, respectively. The height of the villi had been increasing during the whole period of experiment: by 5.9 times in the experiment group; by 6.2 times in the control one.
Discussion and conclusions. The growth rate of the most morphometric parameters was the highest in animals treated with the product "Emprobio", which indicated the positive effect of this biologically active additive on the structures of minks small intestine.