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Subject: Veterinary Pathology × Author: AMARAVATHI, M × Start date: 2010 × Thesis Type: M.V.Sc. ×
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    ThesisItemOpen Access
    PATHOMORPHOLOGICAL STUDIES ON SPONTANEOUS LUNG LESIONS IN SLAUGHTERED SHEEP
    (SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI – 517 502. (A.P) INDIA, 2014-08) AMARAVATHI, M; SATHEESH, K (Major); ANNAPURNA, P; SUBRAMANYAM, K V
    ABSTRACT : Sheep are prone to various infectious and non-infectious diseases that cause significant lesions in the lungs of which pneumonia is a major health problem. Hence, the present study was undertaken in slaughtered sheep to know the incidence and to describe the lesions noticed in the lungs and also to isolate various bacterial agents in possible cases. A total of 988 sheep of either sex and of different age groups from slaughter houses, postmortems and from field mortalities were screened for gross abnormalities in the lungs and representative samples were collected for further studies. Among 988 lungs screened, 187 (18.93%) lungs revealed definite lesions on gross and histopathological examination that were broadly grouped into abnormalities of inflation 22 (11.76%), circulatory disturbances 37 (19.79%), inflammatory conditions 116 (62.03%), parasitic conditions 7 (3.74%), neoplastic conditions 2 (1.07%) and miscellaneous conditions in 3 (1.61%) cases. Abnormalities of inflation comprised of pulmonary emphysema (9.09%) and atelectasis (2.67%). In emphysema, lungs showed pale areas that projected from the surface grossly and giant alveoli microscopically. In atelectasis, dark and depressed areas were noticed grossly and slit-like alveoli microscopically. Circulatory disturbances encountered in the present study included congestion and haemorrhage (10.16%) and edema (9.63%). Congestion and haemorrhage were evidenced by red, patchy areas and haemorrhages grossly that showed engorged blood vessels and haemorrhages in the alveoli microscopically. In edema, frothy fluid on cut section grossly and eosinophilic fluid in the alveoli microscopically were noticed. The incidence of the inflammatory conditions was 62.03% in the present study which constituted various types of pneumonias and pleuritis. Pneumonic changes accounted for 58.82% of lesions that were grouped into bronchopneumonia (56.15%) and interstitial pneumonia (2.67%). Bronchopneumonia was further subdivided into suppurative and fibrinous types. In suppurative bronchopneumonia, cranio-ventral consolidation was seen with mucopurulent exudation on cut section. Chronic cases revealed multiple abscesses. Microscopically, the lumen of the airways was filled with inflammatory exudates comprising of polymorphs in acute cases and mononuclear cells and abscesses in chronic cases. Fibrinous bronchopneumonia was characterized by cranio-ventral consolidation, fibrinous exudation and pleural thickening of lungs besides adhesions to thorax in two cases. Microscopically, the lesion revealed fibrino-cellular exudates in alveoli, bronchi and bronchioles. Interstitial pneumonia was characterized by lungs with rib impressions on the surface grossly and thickened alveolar septa with foetalization of alveolar epithelium microscopically. Pleuritis was observed in 6 (3.21%) cases characterized grossly by excessive thickening and microscopically by fibrosis. An incidence of 3.74% of parasitic conditions that included pulmonary hydatidosis and fasciolosis in the present study. Grossly, hydatidosis revealed a single unilocular cyst deeply embedded in the parenchyma that revealed brood capsules on cut section. Microscopically, an eosinophilic, acellular thick laminated layer lined by degenerated germinal epithelium and slight eosinophilic fluid was seen enclosed by an inflammatory zone and fibrous connective tissue. Pulmonary fasciolosis was characterized grossly by haemorrhagic areas that showed flukes in the parenchyma on cut section. Microscopically, sections of the fluke were observed in the alveolar and bronchial lumen surrounded by mononuclear cells, eosinophils and a few polymorphs. Ovine Pulmonary Adenocarcinoma was observed in 2 cases (1.07%) that showed grayish white lungs grossly and meaty appearance on cut section. Histologically, papillary growths of tumor cells both in alveoli and bronchi into the lumen along with infiltration of mononuclears and neutrophils and variable amounts of fibrous connective tissue were noticed. In the present study, lung lesions with sheep pox (1.07%) and PPR (0.54%) were included under miscellaneous conditions. In sheep pox, grossly, lungs revealed numerous circular, discrete to coalescing pock nodules of varying sizes distributed throughout the parenchyma. Histologically, proliferative alveolitis and bronchiolitis, focal areas of necrosis and presence of sheep pox cells were observed. Ultrastructural changes by TEM showed macrophages with indented nucleus, distorted endoplasmic reticulum and electron dense immature virus-like particles in the cytoplasm. Nuclear changes included karyorrhexis and margination of chromatin. In PPR, grossly, lungs revealed patchy areas of consolidation in apical and diaphragmatic lobes and froth filled trachea on cut section. Numerous giant cells were noticed in the alveoli and bronchi microscopically. In the present study, swabs from 52 suitable lung samples with pneumonic lesions were subjected for bacterial isolation. In 50 lung samples, 8 isolates of bacteria were obtained viz. S. aureus, Klebsiella spp., E. coli, Enterobacter spp., Edwardsiella spp., P. aeruginosa, Pasteurella spp. and Serratia spp. The major pathogen isolated from lungs was S. aureus. The present investigation revealed various lung lesions in slaughtered sheep with an incidence of 58.82%, of these, bronchopneumonia was the predominant lesion causing losses in sheep.