Leucosi mieloide in allevamenti commerciali di broiler.

Avian Leukosis-Sarcoma (ALS) Complex includes a variety of transmissible tumors of birds, caused by Retroviridae.. Lymphoid leukosis is the most common form of the disease, but in recent years myelocytomatosis and myeloblastosis have been increasingly reported in heavy breeders, in commercial hens, and more rarely, in broiler chickens. This paper reports on neoplastic lesions, occurred spontaneously in broilers between 40-50 days on two consecutive productive cycles. The histological study revealed neoplastic cells with pleomorphism, irregularly distributed with atypical mitotic figures, containing eosinophilic granulations, typical features of the myeloid lineage. The early presence of these tumors in chickens from the same breeding supports the hypothesis of vertical transmission, typical of Retroviruses infections. Future immunohistochemical examinations should contribute definitely to the etiology of the disease.