STUDIES ON PATHOMORPHOLOGY OF LUNGS OF SMALL RUMINANTS WITH SPECIAL REFERENCE TO MANNHEIMIA HAEMOLYTICA INFECTION
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Date
2022
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KARNATAKA VETERINARY, ANIMAL AND FISHERIES SCIENCES UNIVERSITY, BIDAR-585401
Abstract
Respiratory disorders are frequent in small ruminants and they are generally difficult to diagnose in live animals until they get complicated. As a result, necropsy examination of the lungs is the only approach to understand the etiology behind respiratory disorders and diagnose them quickly. The aim of the work was to record various gross and histopathological lesions of small ruminants lungs, to correlate histopathological findings in Mannheimia haemolytica induced pneumonia and to confirm M. haemolytica using PCR. A total of 275 small ruminants carcasses were examined and lung lesions were recorded in 235 cases. Lung lesions were most common in the 0-1 year-old age group, with males having the highest rate of occurrence. The middle and caudal lung lobes were found to be less affected than the cranial lung lobes. On cytological examination of 235 samples, 109 were found to be positive for bacilli. Based on gross and microscopic changes, the lung lesions were classified as pneumonia in 208 (88.51%) cases, bronchiolitis in 4 (1.07%) cases and other lesions such as atelectasis in 59 (25.10%) cases, emphysema in 46 (19.57%) cases, haemorrhages in 12 (5.10%) cases, oedema in 37 (15.74%) cases and congestion in 33 (14.04%) cases. Pneumonic lesions were classified into acute bronchopneumonia, sub-acute bronchopneumonia, suppurative bronchopneumonia, fibrinous bronchopneumonia and acute interstitial pneumonia. PCR for Lkt gene of M. haemolytica was carried out on 109 lung tissue samples showed 22 (10.57%) positive cases and these were mainly from fibrinous bronchopneumonia (95.5%) and suppurative bronchopneumonia (4.54%). The study concluded that M. haemolytica causes mainly fibrinous bronchopneumonia.