An Epizootic of Equine Sarcoid

Abstract

JACKSON¹ first recognized and described equine sarcoids, which are locally aggressive, fibroblastic tumours of equine skin. They are often multiple, frequently recur following surgical excision or radiotherapy, and generally have fibropapillomatous features. Horses, donkeys and mules are susceptible. Neither a seasonal incidence nor an age distribution of equine sarcoids has been detected². Jackson pointed out that the gross and microscopic appearance of the tumours, the predilection sites, and the pattern of spread to secondary sites on affected animals were suggestive of viral aetiology. Auto- and homo-transplantation have been reported^3–6. Voss recently reported that several tumours were produced in horses with centrifuged sarcoid extracts which probably were cell-free although they had not been filtered⁵. Intrader-mal inoculation of bovine papilloma virus in horses produced localized, fibroblastic growths similar to equine sarcoid which suggests the interesting possibility of a causal relationship to equine sarcoid⁷. Equine sarcoid has no known relationship to Boeck's sarcoid in man.