Relevance. The domestic cat (Felis catus) and the eurasian lynx (Lynx lynx) belong to the same family — feline, predatory order. The cat was domesticated more than 10 thousand years ago. Lynx is the most promising animal for domestication. It is successfully bred in fur farms and, which is no longer uncommon, is kept by private owners as a pet. At the same time, the anatomy of these animals has not been studied to date. This makes it much more difficult to provide medical care and does not allow us to trace changes in organs with intensive anthropogenic impact on the body during domestication. In this regard, the study of the morphology of the eurasian lynx is very relevant and timely. Material for research (11 eurasian lynx corpses) wasobtained in hunting farms of the North-Western region of the Russian Federation. Corpses of a domestic cat (mestizos) were obtained from veterinary clinics of St. Petersburg (15 animals studied).Methods. A complex of modern and traditional methods was used in the study: fine anatomical dissection, angiorentgenography, computed tomography; production of corrosive and enlightened vascular preparations, morphometry and photographing.Results. The domestic cat (Felis catus) and the eurasian lynx (Lynx lynx) have significant differences in the topography and branching of the aortic arch and thoracic aorta, despite the close relationship in taxonomy. The eurasian lynx is characterized by the presence of a brachiocephalic trunk and a trunk of common carotid arteries. Similar vascular structures are absent in a domestic cat. For them, the presence of the brachiocephalic artery and the independent departure of the right and left common carotid arteries, without the formation of a common trunk, was established. At the same time, we state that some main arterial transport vessels and their branches in these animals have common principles of location. This pattern has been determined for the vertebral, internal and external thoracic arteries, including their branches of the first order.

The study of the arterial bed of the heart of small domestic animals is of high practical importance in veterinary practice and requires further development and study. The work was performed at the Department of Animal Anatomy, St. Petersburg State University of Veterinary Medicine. The material for the study was five corpses of Maine Coon cats, of which three cats (male) and two cats (females).The methods for the study were fine anatomical preparation and making casts of heart vessels using Flexstep latex milk. According to the results of the study, it was found that the right subsinus artery in a Maine Coon cat is poorly developed and does not participate in anastomosis with the branches of the left paraconal artery in the region of the apex of the heart. In the region of the coronary sulcus, the right anastomotic branch departs from the right coronary artery, which is involved in closing the collateral path of blood supply to the heart of the Maine Coon cat. The blood supply to the heart of a Maine Coon cat is due to the right and left coronary arteries, but the right coronary artery and its branches are less developed compared to the left, which confirms that this cat breed has a left-coronal type of blood supply.

The liver of animals and humans is characterized by polyfunctionality. All the variety of liver functions and the intensity of their course is determined by the peculiarities of its hemodynamics. According to the morphological anatomy of the pig liver, I distinguish six lobes: the right lateral and medial, the left lateral and medial, square and caudate. The functional anatomy of the liver is based on the division of the liver into segments. In this case, the division is based on the fact that each segment has its own double blood supply, bile and lymph outflow routes. The aim of the study is to study the architectonics of the hepatic veins of newborn piglets, to give a morphometric characteristic of the branches of the intraorgan venous bed, as well as the segmental structure of the liver of piglets. The corpses of newborn piglets of the Landrace breed served as the material for the study. Vasorentgenography, fine anatomical dissection, and morphometry were chosen as research methods. The study included 15 piglets of the newborn period. During the study, it was found that four hepatic veins (right accessory, right, left and middle) flow into the caudal genital vein. Hepatic veins have complex intra-organ architectonics and take branches of the first and second order along their course. The maximum diameter is the left hepatic vein, which carries out the outflow of blood from the left lateral and medial lobes of the liver. The right hepatic vein drains blood from the right lateral and medial lobes, the middle hepatic vein drains from the square lobe, gallbladder and part of the left medial lobe. The smallest diameter is characteristic of the right accessory hepatic vein, which drains the caudate lobe.Having studied the intra–organ architectonics of the branches of the hepatic veins, it can be concluded that the liver of piglets has eight segments - one segment each in the caudate, left medial, right medial and square lobes, two segments each in the left and right lateral lobes.

A significant number of CYP450 enzymes of the mammalian body are localized in hepatocytes, which determines the high metabolic capacity of the liver in relation to most foreign substances. Due to the fact that there are no data in the scientific literature on the concentration of CYP450 in the body of laboratory rats depending on the nature of tissue samples, the main goal of our study included studying the variability of the CYPOR concentration level in various biomaterials (blood serum, liver homogenates). Several groups of laboratory rats weighing 180-195 g, of both sexes (n = 20) were formed for the study. At the end of the quarantine, the laboratory rats were humanely euthanized (LEC at the FSBEI HE SPbSUVM, protocol No. 2, dated 04/20/2025) in order to obtain liver homogenate. For this purpose, the samples were placed in a special suspension medium for tissue homogenization (pH=7.4; the basis of the medium is Tris-HCl buffer with the addition of 0.25 M sucrose and a small amount of ethylenediaminetetraacetic acid and sodium salt in order to bind divalent metal ions and glutathione to prevent peroxidation of lipid components. Then, using a homogenizer (Stegler S10, China), 20 homogenate samples were obtained (1 g of tissue per 9 ml of the above medium), which were analyzed by enzyme immunoassay. As a result of the study, the results obtained in the blood serum were statistically unreliable, and amounted to figures in the range from 0 to 470 ng / ml, and often went beyond the sensitivity of the determination method. In the liver homogenates, there was an opposite picture, where the range was from 0.650 to 11.8 ng / ml, the data were representative, reliable.

When keeping fur-bearing animals, it is necessary to take into account that these animals have increased motor activity when they are in natural biogeocinosis. Due to the fact that these representatives of fur-bearing animals are kept in conditions of inactivity, this can inevitably lead to changes in the structure of the cardiovascular system. The purpose of the study is to study the features of the course and branching of extraorgan veins of the organs of urination in Arctic foxes, to determine the morphometric data of these vessels. The objects for this study were the corpses of female arctic foxes of two age groups: newborns and three to four months, five in each group. To achieve this task, a set of traditional anatomical research methods was used. According to the results of the study, it was found that the course and branching of the extraorgan vessels of the organs of urination in female arctic foxes is different. The main outflow of blood from the kidneys are the right and left renal veins; from the ureter – the cranial and caudal branches of the ureter; from the tip of the bladder – the cranial cystic vein; from the body and the bottom of the bladder is the caudal cystic vein. It is also necessary to note the close relationship of the organs of urination with the reproductive system, since the left renal vein communicates with the ovarian. In addition, we have established the presence of rare valves in the veins of the ureters and bladder, and the absence of such in the vessels of the kidneys. Thus, based on linear parameters, it can be concluded that the diameter of the veins gradually increases with the growth of the animal, especially by the period of maturation and intensification of organs.

The heart of a domestic bull, like that of other ruminants, according to domestic and foreign authors, has a leftcoronary type of blood supply, which is caused by the dominance of the left coronary artery over the right one in relation to the area vascularized by them and the cross-sectional diameter. In a two-month-old Black-and-White calf, only the right coronary artery took part in the blood supply to the heart, while the left coronary artery was completely absent. In this regard, the purpose of our study was to study the features of the vascularization of the left ventricle of the heart of a Blackand-White breed calf with a right-sided type of blood supply. The corpse of a black-and-white calf at the age of two months served as a material for the study. The methods for the study were fine anatomical preparation and making casts of heart vessels using latex. According to the results of the study, it was found that despite the absence of the left coronary artery, the right coronary artery in a two-month-old Black-and-White calf in several areas of the heart has a very similar branching variability. In this regard, we can assume a sufficient level of compensation for the blood supply to the left ventricle of the heart in this calf. It was determined that the main branches of the right coronary artery, which vascularize the left ventricle, in the studied calf in their topography have frequent S-shaped bends and loose type of division, which can increase the risk of coronary heart pathologies. The data obtained confirm the high degree of variability of coronary arteries in animals, regardless of their species and breed. The results of the study can be used by veterinary specialists as a variant of the anatomical development of the coronary arteries of the heart in farm animals and their possible variability.