Gross and histopathological changes in chickens infected with Ornithobacterium rhinotracheale

The present study aimed to investigate gross and histopathological changes in chickens that died with a history of respiratory distress, attributed to ornithobacteriosis. On gross examination, most frequently affected organs found were trachea, lungs and air sacs. The trachea revealed congestion, mild to moderate catarrhal exudation, caseous plugs in the lumen accompanied by haemorrhages. Lungs were most severely affected organs, revealed severe congestion, haemorrhages, edema, inflammatory exudation, areas of consolidation and unilateral and or bilateral pneumonic changes. Air sacs showed varying degrees of airsacculitis, foamy white exudate, predominantly targeting abdominal air sacs. Histopathologically, trachea revealed marked vascular congestion, epithelial necrosis, goblet cell hyperplasia, mucosal destruction, deciliation, fibrin deposition, and inflammatory infiltration. Lung sections showed fibrinopurulent pneumonia, vascular congestion, emphysema, lymphoid aggregates, interstitial fibrosis, and lymphoid hyperplasia. The lung section showed fibrinopurulent pneumonia, vascular congestion, emphysema, heavy infiltration of MNC’s in and around bronchioles in the form of lymphoid aggregates, fibrin deposits in lung parenchyma, thickening of the interalveolar septa and lymphoid hyperplasia. Air sacs exhibited epithelial degeneration, hyperplasia, edema, hemorrhages, fibrinous thickening, and lymphocyte infiltration. Liver lesions included congestion, hepatocellular degeneration, necrosis, bile duct hyperplasia and lymphocytic infiltration were also noted. Spleen showed lymphocyte depletion, corpuscular atrophy, and arterial thickening. Heart exhibited myocardial edema, myofibrillar dystrophy, disorganisation and fragmentation of muscle fibers and mononuclear infiltration. Kidneys showed vascular congestion, hydropic degeneration, glomerulitis, and coagulative necrosis.