Chronic dermatosis and cutaneous squamous cell carcinoma in the beagle dog.

Chronic dermatosis developed in sparsely-haired, lightly pigmented, ventral body skin in 397 of 1 680 beagle dogs by the time the dogs were 5 1/2 years old. Twenty-six of 55 other beagles had developed by 12 years of age. Squamous cells carcinomas developed in the sites of dermatosis in eight of the 397 younger and five of the 26 older beagles. The lesions resembled solar keratosis (solar dermatosis, actinic dermatosis or senile keratosis) in man. They developed under circumstances suggesting that solar radiation is involved in the pathogenesis, as it is in man.