A survey on neoplasia in domestic species over a 40-year period from 1935 to 1974 in the Republic of South Africa. IV. Tumours occurring in Equidae.

A survey was carried out on the neoplasms of horses, donkeys and mules which are recorded in the registration files of the Section of Pathology of the Veterinary Research Institute, Onderstepoort, in the Republic of South Africa, over a 40-year period from 1935 to 1974. A total of 378 tumours are recorded, 339 of which were in horses, 32 in mules and 7 in donkeys. Sarcoids (38%), squamous cell carcinomas (23,5%), fibromas (8,2%), melanomas (8,0%), papillomas (4,5%), fibrosarcomas (3,4%) and lymphosarcomas (3,0%) accounted for 88,6% of the total. Of the 58 sarcoids for which the site or origin was determined, 46,5% occurred on the head, 32,8% on the chest and abdomen, 19% on the limbs especially below the level of the carpus or hock and 1,7% on the neck. Fifty percent of the 89 squamous cell carcinomas occurred on or around the eyes, especially on the eyelids or nictitating membrane, 23% involved the penis and/or prepuce, while just over 20% arose on the skin. The melanomas involved the skin and eye, whilst papillomas originated primarily on the skin and less frequently on the penis.