Occurrence of squamous cell carcinoma in Milchschaf sheep in Uruguay

Abstract

ABSTRACT: In this study, the epidemiological and pathological features of an outbreak of squamous cell carcinoma (SCC) in adult female sheep and a young ram, Friesian Milchschaf breed or crossbreed is described. Seven adult females belonging to an original flock nucleus of 20 animals were affected, as well as a young ram belonging to the same nucleus was affected in other establishment. Multiple verrucous neoplastic masses of several months of evolution were evident in the head region, with local invasion and regional lymph node metastases. Histological studies revealed a cancerous stage of invasion of the dermis and neoplastic proliferation characteristic of invasive SCC, and a pre-cancerous stage with solar elastosis and chronic solar keratosis lesions induced by sunlight. Decrease in latitude, increased level of solar radiation with long exposure to sunlight, and the phenotypic characteristics of the breed are the main factors responsible for the high prevalence of SCC, showing the susceptibility of the Friesian Milchschaf breed and crossbreed in temperate zones as Uruguay.