What is sebaceous adenitis?
This is a perplexing condition in which the sebaceous glands in the skin become inflamed for unknown reasons, and are eventually destroyed. These glands normally produce sebum, a fatty secretion that helps prevent drying of the skin.
Clinical signs vary with the severity of the condition, and between different breeds.
How is sebaceous adenitis inherited?
It appears that the disorder is inherited as an autosomal recessive trait in the standard poodle; however the wide variation in clinical signs suggests that inheritance is not straightforward, and breeding studies continue.
What breeds are affected by sebaceous adenitis?
Sebaceous adenitis is most often seen in the standard poodle, vizsla, Akita, and samoyed. The condition has been diagnosed in many other breeds as well (see resource 1 below).
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.
What does sebaceous adenitis mean to your dog & you?
Sebaceous adenitis is usually first noticed in young adult dogs (1 to 5 years of age). The condition can appear differently in different breeds, and there is also marked variability depending on the clinical severity.
One form of the disorder is seen in long-coated breeds - the Akita, samoyed, and (most-studied) the standard poodle. Typically affected standard poodles have dry scaly skin with patches of hair loss along the top of the head, back of the neck, and back. Silvery scales tightly adhere to tufts of remaining hair. Very mildly ("sub-clinically") affected standard poodles have a normal hair-coat, but abnormalities typical of the condition are seen on microscopic examination of skin biopsies. More severely affected dogs will have areas of thickened skin ("hyperkeratosis"), extensive hair loss and often a musty or rancid odour. Secondary skin infections often occur as well.
The second form of sebaceous adenitis occurs in short-coated breeds such as the vizsla. There is a moth-eaten appearance to the haircoat with mild scaling, affecting primarily the trunk, head, and ears.
Sebaceous adenitis is primarily a cosmetic disorder - that is it affects the appearance of the dog rather than his/her general health. The condition tends to be most severe in the Akita, resulting in chronic secondary bacterial infections, weight loss, and fever.
How is sebaceous adenitis diagnosed?
Your veterinarian may suspect this disorder based on your dog's clinical signs. To differentiate this condition from other skin disorders, many of which are also associated with increased scaling, a skin biopsy is necessary. This is a simple procedure done with local anesthetic, in which your veterinarian removes a small sample of your dog's skin for examination by a veterinary pathologist. The biopsy will show changes in the skin consistent with this condition.
How is sebaceous adenitis treated?
This disorder requires long term management, which can be frustrating for both owners and veterinarians because the response to treatment is highly variable. There may be periods of spontaneous improvement or worsening of the condition, independent of treatment.
Your veterinarian will likely try a combination of approaches, to determine with you what will be most effective for your dog. Most important is the regular use of anti-seborrheic shampoos to remove scales and dead hair, together with fatty acid dietary supplements. This may be all that is required in mildly affected dogs. Additional treatments include spraying the dog with a mixture of propylene glycol and water to help restore lubricants to the skin and the use of oral essential fatty acids.
For the veterinarian: Retinoid therapy and cyclosporine have been used with variable results in refractory cases. Contact the Genodermatosis Research Foundation (GRF) for the most current recommendations on therapy.
Although the genetics have not been determined, the condition does appear to be inherited in those breeds studied. It is thus preferable to avoid breeding affected dogs of any breed, their siblings, and their parents.
The Institute for Genetic Disease Control in Animals (GDC) operates an open registry for sebaceous adenitis in the standard poodle. All dogs that have been used or are intended to be used for breeding purposes, or any dog with a diagnosis of sebaceous adenitis, should be registered through an annual skin biopsy. Bear in mind that subclinically affected poodles (meaning that they have no clinical signs, even though a skin biopsy shows that they have a mild form of the disorder) may produce clinically affected puppies.
The GDC (http://www.vetmed.ucdavis.edu/gdc/gdc.html) provides registration forms, instructions for veterinarians regarding biopsies, and a list of participating pathologists. Registration requires evaluation of two 6-mm skin biopsies by a participating dermatopathologist, who will send the results to the submitting veterinarian and GDC for their computer files.
In sub-clinically affected dogs (those with a normal haircoat), histologic lesions consistent with sebaceous adenitis may not be evident in a particular biopsy sample. Thus a pathologist's report of "normal" does not guarantee that the dog is unaffected, but rather that the skin biopsies examined showed no evidence of the disorder. By having the poodle biopsied and registered annually however, the owner has done all that s/he can to ensure the animal is suitable for breeding, and has contributed information to the registry to decrease the incidence of this disease in the standard poodle.
FOR MORE INFORMATION ABOUT THIS DISORDER, PLEASE SEE YOUR VETERINARIAN.
Campbell, K.L. 1997. Diagnosis and management of keratinization disorders in dogs. ACVIM - Proceedings of the 15th Annual Vet. Medical Forum. pp 220-222.
Dunstan, R.W., Hargis, A.M. 1995. The diagnosis of sebaceous adenitis in standard poodle dogs. In J.D. Bonagura and R.W. Kirk (eds.) Kirk's Current Veterinary Therapy XII Small Animal Practice. p 619-622. W.B. Saunders Co., Toronto.
Genodermatosis Research Foundation (GRF), 1635 Grange Hall Road, Dayton, OH, 45432
Copyright © 1998 Canine Inherited Disorders Database. All rights reserved.
Revised: October 30, 2001.
This database is funded jointly by the Sir James Dunn Animal Welfare Centre at the Atlantic Veterinary College, University of Prince Edward Island, and the Canadian Veterinary Medical Association.