Morphological changes in the small intestine mesentery of cats with infectious peritonitis

Abstract

The research relevance is determined by an insufficient study of morphological changes in the mesentery of cats with infectious peritonitis, even though their understanding is necessary to explain the mechanism of development of the main symptom of the disease – the effusion of fluid into the abdominal cavity. The research aims to establish gross and microscopic changes in the mesentery of the small intestine of cats with infectious peritonitis. The research employs gross and histological examination of the mesentery of the small intestine of cats at the infectious peritonitis. Slides of the mesentery were stained with haematoxylin and eosin. At dry and mixed forms of infectious peritonitis, gross and microscopic changes in the mesentery of the small intestine of cats are similar. In the mesentery grossly, small white spots were found, which protruded above the general surface and had a homogeneous appearance on the section. Microscopic changes in the mesentery of the small intestine of cats with dry and mixed forms of infectious peritonitis were also similar. When conducting histological studies, it was established that the mesothelium on the surface of the mesentery was necrotized or absent. The submesothelial layer of collagen fibres was necrotized or contained partially lysed and fragmented fibres. The loose fibrous connective tissue of the mesentery was swollen, necrotized in places, and infiltrated by lymphocytes, monocytes, and macrophages. Eosinophilic inclusion bodies were detected in the cytoplasm of some monocytes and macrophages. Foci of adipose tissue in the mesentery of the small intestine were infiltrated by lymphocytes and monocytes. Necrosis and destruction of their walls were found in blood vessels and destruction of endothelial cells in lymphatic vessels. Perivascular lymphoid nodules were markedly enlarged due to their swelling and an increase in the number of cells in them. In perivascular lymphoid nodules, expansion of lymphatic vessels and destruction of part of their endothelium cells were also established. Some of the lymphatic vessels of the mesentery were expanded and filled with lymph, which contained a significant number of lymphocytes, monocytes, and single neutrophils. The materials presented in the article are of practical value for anatomists, histologists and pathomorphologists, as well as for scientists who study the pathogenesis of infectious peritonitis in cats

Keywords

• feline coronaviruses
• perivascular lymphoid nodules
• eosinophilic inclusion bodies
• gross changes
• microscopic changes