Sebaceous Adenitis in Dogs

My dog is a Terrier mix and she started losing hair in small patches on her head. The number of hairless areas increased, so I took her to see the veterinarian. After many tests that did not provide a diagnosis, the veterinarian took a skin biopsy. The diagnosis is a condition called sebaceous adenitis. It seems that this is not a very common condition, and I would like more information.

Sebaceous adenitis is an immune-mediated disorder in which there is an inflammatory process directed against the sebaceous glands in the skin. The sebaceous glands are associated with the hair follicles and produce the substance that helps to keep the skin supple and the haircoat soft. Sebaceous adenitis tends to occur in young adult to middle-aged dogs. There are two forms of the disease — one that occurs in short-haired breeds and one that occurs in long-haired breeds. The breeds that are predisposed to sebaceous adenitis are the Standard Poodle, the Akita, the Samoyed, and the Vizsla.

Do the signs of sebaceous adenitis vary between long-haired and short-haired dogs?

The signs of sebaceous adenitis in long-haired dogs include:

• Areas of hair loss that are symmetrical from side to side on the body
• Dull, brittle haircoat texture
• White scales on the skin that do not flake off easily
• Small tufts of matted hair distributed around the body
• Lesions that tend to start on top of the head and along the spine
• In severe cases (common in Akitas), itching and bacterial infection in the hair follicles which may progress to a generalized deep skin infection

The signs of sebaceous adenitis in short-haired dogs include:

• Patchy hair loss that gives a moth-eaten appearance
• Mild skin scales
• Lesions that appear on the head, the ear flaps, and the torso of the body
• Affected dogs may develop scarring in the skin

Short-haired dogs with sebaceous adenitis rarely develop bacterial infections.

Skin biopsy is the only way to diagnose sebaceous adenitis definitively. The pathologist will find areas of infection, inflammation, and scarring in the areas of sebaceous glands. In advanced or severe cases, there may be a complete loss of the sebaceous glands.

How is sebaceous adenitis treated?

Unfortunately, sebaceous adenitis is a challenging disease, as the clinical signs may come and go independent of any treatment that it instituted. There are no studies to support any definitive treatment.

Treatments that are described as variably effective include antibiotics to treat any associated bacterial infection, and medications to interfere with the immune system attack on the sebaceous glands. These treatments may be supplemented with topical treatments to try to soothe the skin and remove the flakes and scales. The Akita is the breed that is most noncompliant to treatment.