Histomorphological changes in the small intestine wall of small domestic animals with eosinophilic enteritis

The aim of research is to study pathomorphological changes in the tissues of the small intestine in case of clinically diagnosed eosinophilic enteritis in small domestic animals. The study was carried out in 2021 on the basis of the Federal State Budgetary Educational Institution of Higher Education of the State Agrarian University of the Northern Trans-Urals, as well as a large veterinary clinic in Yekaterinburg. The object of research was small domestic animals (cats, dogs). A total of 28 tissue samples were studied, taken by diagnostic laparotomy with intestinal biopsy from 21 dogs and 7 cats of different breeds. Subsequent processing and preparation of histological preparations was carried out according to generally accepted methods. Tissue samples were fixed in 10 % buffered formalin for 48 hours. Washing followed by histological processing was performed using a Leica TP1020 automatic tissue processor. The material was dehydrated in alcohols of increasing concentration, exposed to xylene, followed by impregnation with paraffin. The organ samples were embedded in paraffin using a Leica EG1160 embedding station. Histological sections with a thickness of 3-5 µm were prepared on a Leica SM2000R sledge microtome. Histological sections were stained with hematoxylin and eosin using a Leica ST5010 automatic staining station for histological preparations. Micropreparations were analyzed using a Leica DM2500 microscope equipped with a Leica DFC420 video camera and a personal computer. It has been established that a macroscopic sign of eosinophilic enteritis is a thickening of the wall of the small intestine throughout its entire length, an increase in the thickness of the muscle layer is especially pronounced. The main histological signs of eosinophilic enteritis in dogs are: lysis of the intestinal villi over a considerable extent and replacement with amorphous masses or fibrin clots. In cats, the length of the intestinal villi decreases by 50-75 %, which is associated with an autoimmune reaction. With a diffuse form of eosinophilic enteritis of a high degree of activity, diffuse infiltration of intestinal eosinophils and accumulation of eosinophils (more than 50 % of the population of round cells of the lamina propria) are noted in the lamina propria.