Microscopic changes in the organs of broiler chickens with Ornithobacterium rhinotracheale infection

Abstract

Nowadays ornithobacteriosis is widespread among industrial poultry in Ukraine and the world. The disease leads to significant economic losses. The large variation in the serotypes of the bacteria complicates the treatment of the disease. The study of microscopic changes that occur in organs during ornithobacteriosis will help to better understand the pathogenesis of the disease development. Ornithobacteriosis was diagnosed in clinically sick broiler chickens by bacteriological studies using Maldi Tof mass-spectrometry. As a result of the antibiotic sensitivity test, the pathogen was found to be sensitive to doxycycline, tilmicosin, rifampicin, cefazolin, amoxiclav and benzylpenicillin. Histological studies of internal organs – trachea, lungs, heart, kidneys, liver and spleen – were carried out. It was found that with spontaneous ornithobacteriosis of broiler chickens, the most expressive microscopic changes occur in the respiratory organs – the lungs and trachea and are characterized by a decrease in the lumen of the parabronchials due to edema of their walls and infiltration with lymphocytes, the absence of epithelium on the surface of the parabronchials, narrowing of the air capillaries of the parabronchial complexes, hemorrhages in the parenchyma of the parabronchial complexes, vasodilatation of the lung vessels and overflow of their blood vessels with blood cells, edema around the epithelium trachea, destruction of part of the tracheal mucosa epithelial cells, edema of its submucosa, expansion and overflow of blood vessels of the mucous membrane with blood cells. In the spleen there was a uniform diffuse edema of the parenchyma and a decrease in the number of lymphocytes in the lymphoid follicles; in the kidneys – expansion and overflow of the stroma blood vessels, uneven edema of the glomeruli of one part of the renal corpuscles and destruction of the glomeruli of another, granular degeneration of the convoluted and straight tubules of the kidneys; in the liver – edema, hemorrhage, violation of the hepatic lobules’ structure, expansion of the hepatic veins, granular degeneration of hepatocytes or their destruction; in the heart – edema of the myocardial interstitium, muscle fibers’ granular dystrophy, fragmentation of muscle fibers as a result of their rupture. Histological research of ORT infected chickens will lead to a better understanding the mechanism of pathological changes at the microscopic level, which will facilitate the development of more effective methods of treatment and prevention of the disease.