Alopecia

Patty Khuly

Summary

Alopecia is a general term that denotes a loss of hair. For the purposes of this genetic disease library, however, we will restrict our discussion of alopecia to the kinds of localized hair loss known to have a hereditary basis in dogs.

“Focal, non-inflammatory alopecia” is the well-accepted veterinary term for this condition. It occurs in certain breeds of dogs over specific areas of the body: The head, the ears, the chest, the belly and the thighs are often affected.

Various forms of hereditary alopecia have been identified: Pinnal alopecia, pattern baldness, post-clipping alopecia, post-injection alopecia (usually after rabies vaccination), color dilution alopecia and alopecia areata are the most commonly described forms of focal, non-inflammatory alopecia. Follicular dysplasia, another form of non-inflammatory alopecia, is treated separately for the purposes of this genetic disease library.

Endocrine disorders, skin infections, allergic skin disease, immune system dysfunction and other conditions may factor into the presence or severity of these alopecic conditions.

With the heritable versions of alopecia, no other symptoms of disease are usually present. It tends to be considered a purely cosmetic problem.

Symptoms and Identification

Hair loss is the principal symptom. The pattern of loss varies depending on the form of the alopecia.

  • Pinnal alopecia: The ear flaps are primarily affected.
  • Pattern baldness: Hair loss over and behind the ears, the legs and the belly is common with this version. In affected dogs it begins at around six months and progresses to near-complete hair loss over the next 12 months. Females are predisposed.
  • Post-clipping alopecia: This occurs, usually in heavy-coated breeds, over areas that have been recently clipped (as for surgery or as is often done in warmer climates).
  • Post-injection alopecia: This appears as a patch of hair loss confined to an area of recent rabies vaccination.
  • Alopecia areata: The head and neck are most likely to suffer alopecia but the loss of hair can happen anywhere on the body with this disease. Over time, the areas of hair loss may turn grey or black with extra pigment deposition.
  • Color dilution alopecia: Generalized hair loss, skin dryness and bumps related to secondary infection of the hair follicle are typically seen starting in 6 month-old pups and progressing into adulthood.

In all cases, biopsy of the skin is indicated, as is basic blood testing to rule out other skin-related systemic disorders, particularly of the endocrine or autoimmune variety.

Affected Breeds

Addison’s disease appears to be more prevalent in the following breeds:

Treatment

Most alopecia cases are untreatable, per se. However, treating secondary symptoms (such as skin infections) and complicating diseases (such as hypothyroidism) are a necessary adjunct in many hereditary alopecia cases.

The drug etretinate and the supplement melatonin have been reported to have some degree of efficacy treating some forms of hereditary alopecia.

Veterinary Cost

Untreatable as the hereditary forms of alopecia are, the cost of diagnosis is typically the full extent of the expenses owners with affected dogs incur. This is normally confined to the cost of basic skin biopsies and the labwork required to rule out alternative causes and/or ensure no underlying diseases are complicating the condition.

Prevention

There is no known means of prevention save genetic counseling which would serve to eliminate affected dogs and their Preventing hereditary alopecia is usually accomplished through breeding management. Affected dogs and all their first degree relatives should not be bred.



References

Rosenbaum, Michele, 2001. Focal, non-inflammatory alopecia: A diagnostic, treatment challenge. DVM Newsmagazine.

Scott, D.W., Miller, W.H., Griffin, C.E. 1995. Muller and Kirk's Small Animal Dermatology. p. 777. W.B. Saunders Co., Toronto.

Power, H.T., Ihrke, P.J. 1995. The use of synthetic retinoids in veterinary medicine. In S.J. Ettinger and E.C. Feldman (eds.) Textbook of Veterinary Internal Medicine. p 585-590. W.B. Saunders Co., Toronto.