Alopecia X is the name given to a cosmetic condition found primarily in Nordic breeds of dogs, as well as miniature and toy poodles. The primary symptom of alopecia X is the loss of coat ( alopecia is the medical term for hair loss). This is actually a hair cycle problem where the normal shed and growth patterns are disrupted. The dog sheds hair and fails to regrow a normal coat.
The primary clinical presentation of alopecia X is the symmetrical, gradual loss of hair over the trunk and thighs, while hair on the head and front limbs remains normal. Sometimes the guard hairs are lost first, leaving a soft "puppy" coat. The skin may also darken, called hyperpigmentation. Other terms for the condition in veterinary literature include adult onset growth hormone deficiency, growth hormone-responsive alopecia, castration-responsive alopecia, and, more recently, adrenal hyperplasia-like syndrome. Breeders of Alaskan malamutes often refer to it as coat funk and Pomeranian breeders call it black skin disease.
The primary symptom is symmetrical coat loss. It often starts on the flank and rump near the tail and spreads forward up the sides of the dog. However, some dogs lose coat around the neck first, followed by loss of coat on the back hind quarters. The coat loss may be gradual and not noticed by the owner at first. The dog seems to shed normally, but the coat doesn’t grow back in some areas. Sometimes coat will grow back at the site of a trauma. For instance, a typical step in diagnostics is for the veterinarian to do a punch biopsy. A thick tuft of hair will often grow at the site of the biopsy.
Both sexes are affected, and the condition may appear as early as nine months or as late as 10 years old. Both intact and neutered dogs can have the condition, however neutering will often cause the coat to grow again at least for one cycle of growth. Spontaneous regrowth sometimes occurs with no known cause. This may happen as quickly as one year later.
Alopecia X is a catchall term that may be describing more than one disease with similar types of hair loss. There is no single known cause. In some cases it may be a hormone imbalance. Some cases are believed to have a genetic link, and there is ongoing research to try to identify the genes involved.
There is no specific diagnostic test for alopecia X. It is usually a matter of ruling out other causes of the symptoms. Your veterinarian will first have to examine the dog for other possible causes of coat loss, such as hypothyroidism, Cushing's syndrome, sebaceous adenitis, parasites, and skin infections. Thyroid screening, testing for Cushing's syndrome and sometimes a punch biopsy may be performed.
The ACTH (adrenocorticotropic hormone) response test with measurement of sex hormones and precursors can be preformed by specialty laboratories, such as one at the University of Tennessee College of Veterinary Medicine. However, this test is expensive and not 100-percent conclusive; therefore, it is not recommended by many veterinarians because they consider alopecia X to be primarily a cosmetic condition.
There is no treatment that is 100 percent effective. Castration or spaying is the first recommendation for intact dogs. This will often cause the coat to recycle, but it is important to understand that it may recycle only once. About 30 to 40 percent of dogs respond to oral melatonin given twice per day. This is considered a safe treatment but should be used only if a veterinarian has ruled out other possible causes of hair loss. It should not be used in diabetic dogs without consulting a veterinarian because some adverse reactions have been reported. As with castration, the coat may recycle only one time, and then symptoms may begin to appear again. Some dogs do respond to melatonin with permanent results so that the coat cycles normally from that point on.
Melatonin is readily available over the counter as a nutritional supplement. Nutritional supplements are not regulated by the Food and Drug Administration in the same way as drugs, so there may be variability in potency from brand to brand and bottle to bottle.
Research has been done on treatment with growth hormones and drugs that alter the adrenal glands’ production of cortisol and sex hormones. These treatments are experimental and have the potential for serious side effects.
Dogs with alopecia X may have more flaking of the skin and are more susceptible to the cold and to sun exposure. Consider putting a t-shirt on your dog if it will be in the sun for any length of time and a coat or sweater if the dog is going to be outside in the winter when temperatures are low. Exposure to the sun may cause the skin to darken. Maintain your dog’s remaining coat with a routine of bathing, brushing, and trimming. This will help you to be aware of any secondary skin infections or changes in the coat, and the stimulation is good for the health of the skin.
Elizabeth Wells, Ph.D. - Michigan State University
Treatment of canine Alopecia X with trilostane, by Rosario Cerundolo, David H Lloyd, Angelo Persechino, Helen Evans and Andria Cauvin, Veterinary Dermatology 2004; 15(5): 285-293.
Adrenal steroid hormone concentrations in dogs with hair cycle arrest (Alopecia X) before and during treatment with melatonin and mitotane, by Linda A. Frank,Keith A Hnilica and Jack Oliver, Veterinary Dermatology 2004; 15(5): 278-284.
Identifying "look alike" endocrine diseases, by Pat White DVM MS diplomat ACVD DVM June 2001.
Black Skin disease - Mapping Canine X Chromosome Linked Alopecia: Canine Health Foundation Grant Gary Johnson, DVM, Ph.D., University of Missouri, Columbia.