Original Research

Ovine pulmonary adenocarcinoma in slaughtered sheep: A pathological and polymerase chain reaction study

Shahrzad Azizi, Elahe Tajbakhsh, Farzad Fathi
Journal of the South African Veterinary Association | Vol 85, No 1 | a932 | DOI: https://doi.org/10.4102/jsava.v85i1.932 | © 2014 Shahrzad Azizi, Elahe Tajbakhsh, Farzad Fathi | This work is licensed under CC Attribution 4.0
Submitted: 24 September 2012 | Published: 27 February 2014

About the author(s)

Shahrzad Azizi, Department of Pathology, Shahid Bahonar University of Kerman, Iran, Islamic Republic of
Elahe Tajbakhsh, Department of Microbiology, Islamic Azad University, Iran, Islamic Republic of
Farzad Fathi, Veterinary Medicine School, Islamic Azad University, Shahrekord Branch, Shahrekord, Iran, Iran, Islamic Republic of


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Abstract

Ovine pulmonary adenocarcinoma (OPA) is a contagious tumour in sheep caused by jaagsiekte sheep retrovirus (JSRV). This tumour originates from the pneumocyte type II and Clara cells and grossly appears as hard, prominent nodules in different lobes. The clinical signs of the disease are similar to those of other chronic respiratory diseases and are not pathogonomic. Therefore, post mortem examinations and histopathological studies are the most reliable ways to diagnose OPA, particularly subclinical cases of this neoplasm. In this study, out of 1000 sheep lungs grossly inspected, 50 animals were suspected of OPA. The suspected lungs as well as 25 apparently normal lungs were examined by histopathological and PCR methods. The proviral DNA was detected in 1/25 apparently normal lungs and 8/50 of the suspected lungs and subsequently confirmed by histopathological studies. The PCR-positive lung samples from five sheep revealed lesions of ’atypical’ OPA and those from three sheep showed the ’classic’ form of the disease. The tumours were multifocal and the masses were distributed throughout the cranioventral and diaphragmatic lung lobes. The stroma of the tumours in the atypical cases was more severely affected with inflammatory cell infiltration and connective tissue proliferation. The histopathological characteristics of maedi including hyperplasia of the perivascular and peribronchiolar lymphoid cells, interstitial lymphoplasmacytic infiltration and smooth muscle hyperplasia were also associated with OPA, especially the atypical form of this adenocarcinoma. Atypical OPA was more prevalent than the classic form. Geographic and climatic conditions, duration of exposure to the virus and the immune status of individual animals might be responsible for the differences between the two pathological entities of OPA.

Keywords

Ovine pulmonary adenocarcinoma; Sheep pulmonary adenomatosis; PCR; Pathology

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