Sebaceous Adenitis
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The cause of sebaceous adenitis is unknown but the end result is inflammation of the sebaceous or oil gland associated with the hair follicles. Loss of the sebaceous gland leads to dysfunction of normal hair growth which results in hair loss. The underlying cause is probably a combination of genetic predisposition and immune-mediated sebaceous gland inflammation.
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Sebaceous adenitis is an inflammatory disease that mostly affects young adults to middle-aged dogs. Cats are rarely affected. Some breeds of dogs that are prone to sebaceous adenitis include Standard Poodles, Akitas, Vizslas, Samoyeds, and Belgian Sheepdogs. It is believed to be a recessive inherited trait in Standard Poodles.
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Most dogs will show a bilaterally symmetrical hair loss and excessive scaling, especially around the face, head, ears, and trunk. Some dogs may develop a bald “rat-tail”. Many dogs may have a secondary bacterial infection of the skin with pimples, crusting, and possible odor. Belgian Shepdogs may have a severe draining ear infection. Vizslas and Dachshunds often have circular areas of crusting of hair loss that can spread and eventually merge together. The hairs of affected animals often have adherent surface debris surrounding the base of the hair called ‘hair casts’. Akitas often have more severe disease with red inflamed skin and greasy crusting and matting. Sebaceous adenitis is usually not itchy but can be if there is a secondary infection.
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See Clinical Signs.
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Sebaceous adenitis is suspected when the history and clinical signs are consistent. Microscopic examination of hairs from dogs with sebaceous adenitis often shows obvious hair casting. The definitive diagnosis of sebaceous adenitis is made by taking a skin biopsy which involves removing small pieces of skin after numbing the area with anesthetic and submitting the skin samples to a pathologist.
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Some dogs can spontaneously improve but most dogs need lifelong control of their sebaceous adenitis. It is mostly a cosmetic disorder with no internal manifestations of disease.
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The treatment for sebaceous adenitis may involve anti-inflammatory therapy, retinoid drugs or vitamin A along with anti-scaling shampoos and emollient rinses. Treatment of secondary infections, if present, is also important. Some dogs respond better to some treatments than others, and trying different therapies may be necessary. The goal of therapy is to alleviate and slow progression of symptoms, but only partial improvement may be seen.
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Prevention of sebaceous adenitis involves not breeding affected animals.
