Congenital Hypotrichosis

Hypotrichosis, the complete or partial absence of normal hair, has been identified as a heritable trait in many mammalian species including mice, rats, cats, dogs, guinea pigs, and primates.

Canine hypotrichosis is usually associated with the presence of less hair than normal. Both hypotrichosis, sometimes called regional alopecia, and alopecia can be congenital (present at birth) or may occur later in the animal's life. These defects can be associated with abnormalities of the female reproductive organs (abnormal or absent adnexa), with defects in other structures (such as teeth, claws, and eyes), or with skeletal and other developmental defects. At least 13 types of hypotrichosis have been described in cattle.

Genetically-linked hypotrichosis has been recently reported in German Shepherds. Dachshunds are predisposed to hypotrichosis and alopecia. Compared to other dog breeds, the young animals are affected more frequently. The most frequent causes - hormonal disturbances (increased and perhaps decreased thyroid function and hyperadrenocorticism), seborrhoea and inherited diseases.

In young adult Chesapeake Bay retrievers (CBRS) symmetrical hair loss affects the same areas of the body in male and female dogs. Hormonal investigations usually show increased adrenal and sex steroid concentration and malformed hair shafts. A familial predisposition seems likely and selective breeding might reduce the occurrence of this condition.

SIGNS The hair loss is bilateral and usually affects certain areas: temples, ears, undersurface of the body, back, or it can involve the whole body. Later skin thickening and pigmentation may occur, and seborrhea is sometimes seen. Skin tests reveal normal hair follicle density although follicles are empty or contain keratin debris and fragments of hair shaft.

TREATMENT There is no effective treatment for this inherited condition. Affected dogs should not be bred.

Congenital Hypotrichosis has been reported in the following breeds:American Cocker Spaniel, Basset Hound, Beagle, Belgian Shepherd, Bichon Frise, French Bulldog, Dachshunds, Labrador Retriever, Lhasa Apso, Rottweiler, Toy and Miniature Poodles, Whippet, Yorkshire Terrier. There may be a sex-linked inheritance as males are usually affected.

References:
1. R. CERUNDOLO, E. A. MAULDIN, M. H. GOLDSCHMIDT, S. L. BEYERLEIN, K. R. REFSAL, J. W. OLIVER (2005) Adult-onset hair loss in Chesapeake Bay retrievers: a clinical and histological study Veterinary Dermatology 16 (1), 39–46