EQUINE SARCOID .1. CLINICAL TYPES, PREVAL ENCE, EPIDEMIOLOGY, ETIOLOGY AND PATHOGENESIS

Equine sarcoids are cutaneous neoplasms which have been described freq uently in horses, donkeys and mules. They are often locally aggressive but do not metastasize into organs other than the skin. Clinically fo ur different types can be differentiated. The verrucous and fibroblast ic forms are most commonly observed. Diagnosis is based upon the clini cal appearance of the lesions and histological examination. Sarcoids h ave been reported to occur singly or multiply on any part of the body, and horses of all ages and breeds can be affected. A genetically dete rmined predisposition to sarcoid development has been found in certain breeds or families. The exact aetiology and pathogenesis of equine sa rcoids remain unclear. There is evidence for a causal association betw een bovine papilloma virus (BPV) and equine sarcoid, but insufficient information is available on the course of the infection, incubation pe riod or transmission possibilities.