Observations on squamous cell carcinomas of sheep in Queensland, Australia

Observations were made over a 4-year period on squamous cell carcinomas on the ear and other areas poorly covered by hair or wool, sheep pastured in the hot, dry environment of north-western Queensland. Overall incidence in the flock was higher than in flocks kept at greater latitudes. Increased incidence with advancing age was demonstrated, and ewes appeared to be more susceptible than wethers. Metastases were observed in 4 of 33 affected ewes (12%) submitted to detailed necropsy examination. Measurements of tumour growth in 4 ewes revealed an increase in size of about 3-5 mm per month. Ovine aural squamous cell carcinoma was considered to be a good model for studies on skin cancer in man.