In the lung tissue morphohistochemical researches have shown that the exudative form often develops catarrhal bronchopneumonia, which is accompanied by hyperemia, edema of stromal elements and vessel walls, macrophage infiltration of the lumen of the bronchial alveoli, combined with necrobiosis, desquamation of the epithelium of the bronchial mucosa and mucus hypersecretion. In the dry form, the development of interstitial pneumonia is registered, which alternated with areas of atelectasis, emphysema and bronchiectasis and productive necrotic arteritis. Along the course of many branches of the pulmonary artery, powerful cellular infiltrates.
By optical research of the myocardium in the wet form was found: disorganization of the walls of the arterioles, their mucoid, fibrinoid swelling and necrosis, stroma edema, diapedetic hemorrhage. In the dry form, the myocardium is dominated by proliferative-destructive vasculitis, perivasculitis, diffuse or focal lymphoid-histiocytic-neutrophilic infiltrates.
In the liver of cats in the wet form was found protein-fat dystrophy of hepatocytes, fibrinoid swelling and fibrinoid necrosis of the vessel walls, moderate round-cell infiltration in the triad area. In the dry form in the liver of cats, the development of productive inflammation was found, is accompanied by the formation of extensive perivascular, periductal round cell infiltrates, duct proliferation, cholestasis, lymphangitis and the formation of nonspecific granules in the liver parenchyma.
In the pancreas, the most severe changes are developing in the vascular system. In the wet form, mucoid, fibrinoid swelling and fibrinoid necrosis of vascular walls were found, and in the dry form - perivascular round cell infiltrates and productive fibroblastic interstitial pancreatitis.
Morphohistochemical researches have identified features of changes in the stomach, duodenum and jejunum of cats. In the wet form of the disease, edema of the muscular and submucosal layer develops, dilatation of venous vessels and capillaries, fibrinoid edema and necrosis of arterioles is pronounced. These changes are combined with necrosis of the apical mucosa of the stomach, jejunum, hyperplasia and hypertrophy of the goblet cells of the villi. In the dry form in the walls of the submucosal layer, the mucous membrane of the stomach and intestines, proliferative processes are predominated.
Morphohistochemical researches of the kidneys in the wet form revealed: serous glomerulonephritis, protein-fatty dystrophy of the epithelium of the convoluted tubules, fibrinoid swelling of the walls of arterioles, edema, and loosening of the interstitium and excessive formation of glycosaminoglycans, glycosides. In the dry form - acute interstitial nephritis in combination with tubulopathies, serous glomerulonephritis, vasculitis and perivasculitis.
In the spleen of cats in the wet form progresses the reduction of white pulp (a sharp decrease in T- and B-lymphocytes) mesenchymal dysproteinosis. In the cytoplasm of macrophages, on preparations stained by Brashe, are different in size pironinofilni inclusion. In the dry form - on the background of angiopathies, intense blood supply to the red pulp, hyperplasia of the lymph nodes is founhd out, mainly due to T-lymphocytes.
In the mesenteric lymph nodes of cats in the wet form of FIP found a sharp decrease in populations of various cells of the cortical, paracortical and cerebral zones, which was combined with stroma edema, exposure of the reticular skeleton, its impregnation with glycoproteins, glycosaminoglycans.In cats in the dry form in the lymph nodes changes are heterogeneous develop sinus histiocytosis and moderate colonization of the cortex substance and cerebral cords by cells of the lymphoid series. It is possible to detect macrophages with small pyroninophilic inclusions in the cytoplasm.
Neurohistochemical researches in the frontal cortex of cats have revealed disorders of hemomicrocirculation, angiopathy, regressive changes in glial elements, acute swelling of neurons.
It is set up that the characteristic microstructural ostent of FIP is generalized vascular damage: in the wet form in the parenchymal and peripheral immune organs prevail vascular-stromal dystrophies: mucoid, fibrinoid swelling, fibrinoid necrosis, amyloidosis of the walls of arterial vessels, and in the dry form - the development of periarteritis and granulomas.
The designated presence of acidophilic inclusions in the cytoplasm of macrophage elements of the excreted peritoneal fluid and macrophages of the lungs, lymph nodes, spleen, pancreas should be attributed to specific changes in FIP.
Key words: infectious peritonitis of cats, FIP, lungs, liver, pancreas, kidneys, spleen, mesenteric lymph nodes, cerebral cortex, macrophages, acidophilic inclusions.
