Epidemiology: Open Access
Open Access

Abstract

M annheimia haemolytica is an etiological agent of pneumonic pasteurellosis diseases causes huge economic loss to livestock population. In present study the clinico-pathological lesions were observed in naturally infected thalli sheep due to M. haemolytica infection. The infected animals revealed signs of moderate to acute anorexia, dysponea, salivation, fever and mucopurulant nasal discharge. Necropsy examination was conducted within 1h to observe the gross changes. The study revealed that the mortality was significantly (P<0.02) high in young animals as compare to adult. Necropsy of sheep exhibited severe froth in trachea, congested and consolidation of lungs, pulmonary edema, severe pleural adhesions, pericarditis, hemorrhages on jejunal mucosa and kidneys. The morbid tissues were collected from different visceral organs such as lungs, liver and lymph nodes and fixed in 10% neutral buffered formalin for light microscopy. Histopathological examination of affected lungs exhibited circumscribed necrotic areas centrally calcified and punctuated with chronic inflammatory cells. Bronchial epithelial hyperplasia, multiple microabcess with caseated centers, edema, congestion, mononuclear cell infiltration, thick interlobular septae and peri-vascular cuffing were the striking changes in lungs. In addition lungs also revealed severe fibrin deposits on pleura along with abundant amount of fibrin meshwork infiltrated with chronic inflammatory cells. Histologicaly the liver, kidneys and lymph nodes showed degenerative changes. M. haemolytica was identified on the basis of growth and morphological characteristics, catalase and oxidase positive while indol and urea negative tests. The clinical signs, necropsy lesions and histopathological findings are useful tools for the development of vaccines and different strategies to control Mannheimia haemolytica infection.

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