Canine Alopecia - Alopecia X

Alopecia X (growth-hormone/castration responsive dermatosis adrenal sex hormone alopecia, pseudo-Cushing's) has to be the most frustrating area to discuss, as this condition is poorly understood and has many names! Classically, this was first described in the early 1980s at the University of Tennessee in the Pomeranian breed. The affected dogs were young adults and had striking alopecia on the trunk, ventral neck, caudal thighs, and lateral trunk. In the original studies in the affected Pomeranians, abnormal sex hormone results were seen with ACTH stimulation. The affected dogs had exaggerated and elevated levels of progesterone and certain androgens.

Research in humans with a similar condition suggests a deficiency or partial deficiency in adrenal enzymes. Thus, at one point it was speculated in the dog a deficiency of 21- dehydroxylase was present resulting in abnormalities in steroidogenesis and ultimately abnormally high levels of certain adrenal gland sex hormones. Therefore, the term adrenal gland hyperplasia-like syndrome was also coined recently! Unfortunately, some normal appearing Pomeranians also had some of these abnormal hormonal levels and recent evidence suggests the condition may not be related to just elevated progesterone's and androgens. Moreover, treatment response based upon sex hormone levels often fail. As a result, and in conjunction with insufficient data since this original study, there is a fair amount of confusion and controversy.

The alopecia can start at an early age and be progressive. Initially, alopecia may involve only the primary or guard hairs giving the dog a "puppy coat" appearance Photos 6 and 7, p. 16S). Affected areas can be very scaly and pustules and papules can also be seen. Diagnosis is made generally with skin histopathology but ruling out other conditions'.

These can include hypothyroidism, Cushing's disease and follicular dysplasia. Treatments can include neutering, melatonin, oral methyl testosterone and even Lysodren. All have occasionally resulted in partial or complete regrowth of hair but alopecia may redevelop while on therapy.

Alopecia X has goes by many names:

  • Black Skin Disease
  • Growth Hormone Responsive Alopecia
  • Castration responsive Alopecia
  • Coat Funk
  • Follicular Dysplasia of the Siberian Husky
  • Post-clipping Alopecia
  • Adrenal Sex Hormone Alopecia

Alopecia X seems to be a sex hormone imbalance in at least some cases and did not earn the name "castration responsive alopecia" for nothing, generally late onset (5 to 7) and mainly affects males . For this reason, the first step in treatment is to sterilize the patient; many animals will grow their hair back (though possibly not permanently

References:  Carlo Vitale, DVM, Dipl. ACVD

Colour Dilution Alopecia

What is colour dilution alopecia?

This condition develops in some, but not all dogs that have been bred for unusual coat colour, especially "fawn" (a dilution of a  normally red or brown coat) or "blue" ( a dilution of the normal black and tan coat colour). Alopecia means hairlessness - affected dogs have a poor, patchy haircoat progressing to widespread permanent hair loss. At the cellular level, there are abnormalities of the hair follicles and uneven clumping of pigment (melanin) granules in the hair shafts in affected areas

The inheritance is unclear. The condition is thought to be due to the interaction of different factors at the gene position for colour. It is not simply determined by the genes at that locus, because not all dogs with colour dilution develop coat problems.

This condition is seen most commonly in Doberman pinschers with unusual coat colours (as many as 90% of blue Dobermans and 75% of fawns). The condition also occurs but is less common in other breeds bred for unusual coat colours: Bernese mountain dog, Chihuahua (blue), Chow Chow (blue), Dachshund (blue), Great Dane (blue), Irish setter (fawn), Miniature Pinscher (blue), Saluki, Schipperke (blue), Shetland sheepdog (blue), Standard poodle (blue), Whippet (blue), Yorkshire terrier (grey-blue).

For many breeds and many disorders, the studies to determine the mode of inheritance or the frequency in the breed have not been carried out, or are inconclusive. We have listed breeds for which there is a consensus among those investigating in this field and among veterinary practitioners, that the condition is significant in this breed.

Dogs with this condition are born with a normal hair coat. Those with lighter blue or fawn hair coats usually start to show changes by 6 months while in dogs with darker steel blue coats, the changes may not be evident until 2 or 3 years of age. Your dog will experience hair loss and dry skin. Sometimes the earliest sign is a recurring bacterial infection (folliculitis), generally on the back, where you will see small bumps which are infected hair follicles. This clears up temporarily with antibiotics, but the affected area is very slow to regrow hair, or remains hairless.

Hair loss is usually first apparent on the back and by 2 or 3 years has spread over all the light coloured areas of the body. The exposed skin is often scaly and is susceptible to sunburn or extreme cold. Your dog's health is not otherwise affected by this condition.

Your veterinarian may suspect this disorder if your dog has typical hair coat changes and is an unusual colour for the breed. The diagnosis is confirmed through microscopic examination of plucked hairs or a skin biopsy. The latter is a simple procedure, done with local anaesthetic, in which your veterinarian removes a small sample of your dog's skin for examination by a veterinary pathologist. The biopsy will show changes characteristic of this condition.

For the veterinarian:  Careful microscopic examination of plucked hairs will show large clumps of melanin distributed unevenly along the hair shaft.

In young dogs, demodicosis or other inherited hair defects should be considered while in dogs with a later onset (2 to 3 years of age), endocrine disorders (particularly hypothyroidism) should be ruled out.

Treatment

Your dog can lead a normal healthy life with periodic symptomatic treatment as needed - moisturizing rinses for dry scaly skin or antibiotics for bacterial infections.

Since early hair loss occurs due to breakage, you may be able to slow the rate of loss by avoiding harsh shampoos and vigorous grooming.

For the veterinarian:  There have been some early reports of hair regrowth using etretinate treatment . (See resource below.)

Breeding advice

Affected dogs, their parents and siblings should not be used for breeding. The condition can be entirely avoided by the use of non-colour-diluted dogs in breeding programmes

Resources

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.

Copyright © 1998 Canine Inherited Disorders Database. All rights reserved.

Other causes of hair loss

Dog hair loss may also be caused by hormonal problems, such as:

 

 









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