Sebaceous Adenitis (SA) is an immune-mediated disease that causes destruction of the sebaceous glands (oil producing glands in the skin). These glands produce sebum, which helps with normal turnover of the skin cells, lubrication of the skin and hair, and antimicrobial properties. Clinical signs are variable depending on the normal coat length and texture.
Symptoms of Sebaceous Adenitis
In long-coated breeds, early signs may include straightening of curly hair, changes in hair color, or coarsening of hair texture with progression to hair loss and marked scaling (known as follicular casting, which is a waxy, adherent type of scaling). In short-coated breeds, circular areas of scaling and hair loss (alopecia) are the most common appearance. Itching and inflammation are variable in sebaceous adenitis, but many dogs have minimal itching. Lesions generally affect the entire body, with the trunk, ears, and head being the most common sites.
Standard Poodles and poodle mixes, Akitas, Vizslas, Samoyed, and Havanese are commonly affected breeds. However, sebaceous adenitis has been seen in many other purebred and mixed breeds. There is a suspected genetic/inherited component in many of these breeds, but the most well-known research is focused on the genetic component of sebaceous adenitis in Standard Poodles.
Diagnosis of Exclusion
Sebaceous adenitis mimics many common skin conditions since it resembles the inflammation and itch seen with allergies, as well as hair loss and scaling provoked by other infectious causes. Therefore, it is very important to have a full work up to get a confirmed diagnosis. In general, skin scrapings and cytology samples are usually collected to rule out skin infections and parasites that can cause scaling and hair loss. History and a full dermatological exam may reveal subtle lesions (particularly follicular casting) that are more indicative of sebaceous adenitis than allergies. However, the ultimate diagnosis is made via biopsies, which will show complete absence of sebaceous glands.
Prognosis and Treatment of Sebaceous Adenitis
Since sebaceous adenitis is primarily a cosmetic disease, long-term prognosis for overall health is good. However, treatment to help with scaling, itch, and hair regrowth is generally recommended for comfort and quality of life. Although labor intensive, the use of topical therapy to remove scaling (seborrhea products) and oil replacement soaks are a major component of treatment, since they are the safest long-term treatments. In more severe cases, immune-modulating therapies, including cyclosporine or steroids, may be recommended for improved resolution and hair regrowth. Mild supplements, such as vitamin A and omega fatty acids, may be discussed as supportive care options. The prognosis for hair regrowth is variable and depends on an individual pet’s response to therapy. Your veterinarian should discuss the risks and benefits of each treatment plan based on the severity of clinical signs, and recommend a combination of topicals and systemic therapies as needed to get initial improvement. In general, therapies can be tapered and reduced once improvement is noted, however, since this disease can naturally wax and wane, life-long treatment is generally required.