Squamous-Cell Carcinoma of the Vulva of Cattle in Kenya

Abstract

Following diagnosis of 9 cases of squamous-cell carcinoma of the vulva in Ayrshire cows during routine histopathological examinations in Kenya, adult animals were examined in 6 Ayrshire herds and lesions of the vulva were found which were classified as acanthosis, acanthosis with papillomas or cancer. These were found only in unpigmented skin. In 4 of the herds, in which cows were classified according to colour of vulva, 29% 0f 300 head had lesions; 55.5% of unpigmented vulvas and 38.3% of partly coloured vulvas were affected but none that was completely pigmented. The incicidence was similar in the other 2 herds. One case of vulvar cancer was found in a Friesian herd but no lesions were found in a Sahiwal herd with pigmented vulvas. Early changes, acanthosis and papillomas, were studied by histopathological examination and the characteristics of these changes are described. Of 12 specimens of unpigmented vulvar skin 7 had evolving carcinomas that had not been suspected from their naked-eye appearance. Four animals were killed for autopsy and materials from these and 11 other specimens from individual cases were confirmed by histopathological examination as squamous-cell carcinoma. Possible causes are discussed. In view of the high intensity of biologically potent radiation that is probably received in farming areas at high altitude near to the Equator, it is suggested that the lesions of unpigmented skin were induced by solar radiation.