Incidence of ovine pulmonary adenocarcinoma in southern parts of India: A slaughter house based study

Ovine pulmonary adenocarcinoma (OPA) or ovine pulmonary carcinomatosis (previously known as ovine pulmonary adenomatosis) is a contagious tumour forming viral disease caused by the genus beta-retrovirus of retroviridae (jaagsiekte sheep retrovirus). This study was aimed to understand the prevalence of disease in the locality based on histopathological diagnosis and its correlation with age, sex and breed. Out of 903 sheep carcasses examined, OPA was recorded in 44 cases accounting to 4.87%. The gross lesions varied from multifocal greyish nodules to complete consolidation of the lung parenchyma. Histologically, there were single to multiple layers of cuboidal to columnar epithelial cells giving adenomatous appearance. The cuboidal or columnar tumour cells replaced the normal alveolar epithelia and in some cases it formed into papilliform growths that projected into the alveoli. The peribronchial and peribronchiolar lymphoid aggregates were consistent features in most of the cases studied. Argyrophilic nucleolar organizer regions (AgNORs) were counted in representative cases of nodular and consolidated forms of adenocarcinomatosis to assess the rate of cell proliferation. The average AgNOR counts per nucleus were 4.672 ± 0.68 and 3.086 ± 0.537 for nodular and consolidated forms respectively.