Occurrence of squamous cell carcinoma in Milchschaf sheep in Uruguay

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.

摘要：本研究描述了一起暴发于成年母羊与青年公羊的鳞状细胞癌（squamous cell carcinoma, SCC）的流行病学及病理学特征，涉及动物为弗里斯兰乳用绵羊（Friesian Milchschaf）品种或其杂交后代。该原核心种群共包含20只动物，其中7只成年母羊发病；同核心种群的1只青年公羊亦在另一饲养场发病。头部区域可见病程长达数月的多发性疣状肿瘤病灶，伴随局部侵袭及区域淋巴结转移。组织病理学检查显示，存在侵袭性鳞状细胞癌的癌性阶段（真皮侵袭与肿瘤增殖特征），以及由日光诱导的日光弹性变性、慢性日光性角化病癌前病变阶段。纬度降低、长期暴露下的太阳辐射水平升高，以及该品种的表型特征，是鳞状细胞癌高患病率的主要诱因，证实了弗里斯兰乳用绵羊品种及其杂交后代在乌拉圭这类温带地区的易感性。