Ovine pulmonary adenocarcinoma

[1] Clinical signs resemble a non-specific progressive pneumonia, including poor body condition and, particularly after exercise, respiratory difficulty.

[2] The only sign specific to OPA is a watery nasal discharge, consisting of lung fluid produced by the affected lung tissue; lifting the hind legs of the animal above the level of its head will cause large volumes of this fluid to flow from the nostrils.

[citation needed] The retroviral antigen levels of JSRV are very high in OPA tumors and can be detected in the lung secretions of infected sheep.

[citation needed] OPA has been found in most countries where sheep are farmed, with the exception of Australia and New Zealand.

[8] Dolly the sheep, the first mammal successfully cloned from an adult somatic cell, was euthanized after it was confirmed that she had OPA.