Squamous cell carcinoma of the anal and perianal area in a bull.

A squamous cell carcinoma located adjacent to the anus was diagnosed in a 15-year-old light colored Longhorn bull. The tumor restricted the anal orifice to a diameter of 3 cm. Upon histological evaluation, islands of squamous cells were present deep in the dermis and the submucosal connective tissue. It was not possible to determine whether the tumor originated from the perianal region or the anus. This is the first diagnosed and reported occurrence in North America of squamous cell carcinoma in the anal region of a bull.