Pulmonary adenomatosis, also known as bronchioloalveolar lung carcinoma (BAC), is a lung cancer of viral origin that leads to the accumulation of fluid within the respiratory tract. The disease affects humans, sheep, dogs and cats. Sheep BAC is caused by the jaagsiekte retrovirus (JSRV) and is contagious. Feline BAC is not contagious and occurs sporadically and spontaneously in older purebred cats such as Persian and Himalayan.2 Retroviruses are unique for their ability to permanently insert their genetic material into the DNA of host cells. JSRV owes its cancerous nature to a single protein that coats the virus and helps virus entry into cells. Such viral "structural" proteins have not been known before to cause cancer. Clinical signs of canine pulmonary adenomatosis include occasional coughing, excessive panting, especially after exercise, and other respiratory signs that have been present for weeks or months. Appetite and temperature are normal, unless there are secondary bacterial infections.3
Once a radiograph confirms a lung tumor, the next step is surgical removal of the affected lung lobe because normal lung tissue does not accept the doses of radiation required to kill tumor cells without serious consequences, such as fibrosis. Vinorelbine (Navelbine) has been used in dogs with a variety of cancers, and partial responses were seen in two dogs with bronchioloalveolar lung carcinoma.4
Current studies are aimed at detailed analysis of the oncogenic pathways induced by JSRV in animals and the relationship of these virus-induced cancers to human lung cancer. Importantly, the type of lung tumor caused by JSRV is similar in type to about 25% of human lung cancers, a major cause of human cancer mortality.
- Comparative Oncological Studies of Feline Bronchioloalveolar Lung Carcinoma, Its Derived Cell Line and Xenograft. Deborah A. Grossman, Alan L. Hiti, Elizabeth A. McNiel, Yin Ye, Mary L. Alpaugh and Sanford H. Barsky.
- Researchers Discover That Sheep Need Retroviruses For Reproduction (ScienceDaily)
- Pathologic Basis of Veterinary Disease. M. Donald McGavin, James F. Zachary
- Withrow & MacEwen's Small Animal Clinical Oncology. Stephen J. Withrow, David M. Vail, David M. Vail