Congenital hypotrichosis in a Percheron draught horse

A blue roan Percheron foal was born with poorly circumscribed patchy alopec ia of the trunk and legs. Teeth and hoof development were normal. Alopecia was progressive, becoming almost complete by 1 year of age. Histopathologic al findings in a skin biopsy obtained at 7 months of age were consistent wi th severe follicular hypoplasia. Sebaceous glands, epitrichial sweat glands and arrector pilae muscles were normal. The horse is alive and otherwise w ell at 6 years of age, although adult stature is considered small for this breed. The clinical history and histopathological findings are most consist ent with a form of congenital hypotrichosis.