Pulmonary Tumor and Amyloidosis in Commercial Laying Hen

First Study As part of a study on lung aadenocarcinomas in older laying hens, 150 commercial egg-laying chickens were necropsied at 3 years of age. Tumors were identified in 67 of the hens. Grossly visible metastatic tumors in the lungs of a few birds prompted collection of lungs from 50 affected hens for histologic examination. Metastatic adenocarcinomas were identified histologically in the lungs of 9 of the 50 hens . The number of tumors and extent of involvement of the lung parenchyma varied from minimal to extensive. Tumor emboli were occasionally seen in pulmonary vessels. Metastatic foci showing expansive or invasive growth were identified. These findings indicate that vascular spread of adenocarcinomas is more common than previously thought in chickens.Second Study Brown egg-laying hens are highly susceptible to amyloid arthropathy as a result of Entercoccus faecalis and Mycoplasma synoviae infections. Other frequently associated bacteria include E. coli, Salmonella enteridis, and Staphyloccus aureus have been associated with amyloidosis in chickens.