Pathological and epidemiological aspects of ovine pulmonary adenocarcinoma: An overview

Abstract

Ovine pulmonary adenocarcinoma (OPA) has been identified in several sheep rearing countries around the world with the exception of a few countries like Australia, New Zealand and Iceland. The outbreak reports from various countries reveal that OPA has emerged as an important economic and animal welfare problem. In addition to its importance as a veterinary problem, OPA has wider relevance for fundamental studies on cancer as it has pathological and epidemiological features similar to bronchioloalveolar carcinoma in humans. Therefore, OPA has been considered as a useful animal model to study various aspects of pulmonary carcinogenesis. There are no reliable diagnostic tests to detect the disease in the pre-clinical stage. The molecular tests developed to detect the infection in clinical samples are less sensitive and have their own limitations. In the absence of serological tests for diagnosis in the flock, eradication of this disease becomes difficult. It was found that once animals get infected, it becomes carrier for life. Due to unavailability of reliable diagnostic tests and an effective vaccine, the control on spread of the OPA virus is difficult. In India, the disease is rarely studied for the detection of OPA and limited to the outbreaks and histopathological diagnosis only. The present overview discusses the major issues of OPA research related to etiology, epizootiology, pathology and prevention with recent advancement.