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Sebaceous adenitis means inflammation of the sebaceous gland, which is responsible for producing the oily component of sweat. This maintains moisture in the skin and haircoat, and makes the coat look healthy and shiny. When the sebaceous glands are damaged, the coat can become brittle and lifeless, and the skin dry and flaky.

Several possible causes have been proposed for SA. These suggest that SA is :-

1. A developmental, possibly inherited, disorder of the sebaceous glands

2. A disease of the immune system, triggered by an unknown mechanism

3. Part of a more generalised defect in the growth of the skin and hair.

Of these, the first seems more likely in the breeds frequently affected by SA.

Inheritance of SA in the Standard Poodle
Evidence from pedigree and test matings suggests that SA in the Standard Poodle is inherited as a recessive disease. This means that affected dogs have to get a faulty gene from both parents to get this skin disease. Dogs with only one affected gene will appear normal, but may have affected puppies if mated with carriers of this recessive gene. All coat colours are affected equally.

Neither affected digs nor their parents should be bred from once the diagnosis has been made. To assist in identifying affected dogs, the Standard Poodle Club has started an open registery of affected and tested dogs. It is suggested that skin biopsies should be taken every other year from all breeding stock to check for SA. This test will not identify carrier animals.

Clinical Signs
SA mostly affects young and middle-aged dogs of both sexes. While many breeds have been reported with SA, certain breeds appear predisposed. The disease is very variable, signs depending upon breed affected, the degree of inflammation in the skin and the proportion of sebaceous gland affected.

In short coated dogs like the Vizsla, circular patches of hair loss (alopecia) and scaling are seen. These may join up to form large patches. SA-affected dogs are rarely itchy (pruritic) unless there is secondary bacterial infection. In the Standard Poodle, scaling usually precedes alopecia. Signs may be subtle, and may start on the head, ears or feet. Eventually severe hair loss and scaling may be seen.

The Japanese Akita tends to have greasy and scaly coat, with considerable loss of undercoat. A rash may affect the skin, and some Akitas show signs of being unwell, with raised temperature and weight loss. The Samoyed is often affected with severe crusting of the coat, leading to matting and eventual hair loss on the trunk. In the German Shepherd Dog disease often starts on the tail, progressing to involving the rest of the body.

The course of the disease also varies, waxing and waning signs in some dogs; some may even return to normal, although these often relapse.

Making the Diagnosis
The diagnosis of SA is suggested from the history and clinical signs and confirmed by skin biopsy. Confirmation may prove difficult, as inflammation of the sebaceous glands can form a part of many other skin diseases in the dog. To make a diagnosis of SA, either specific changes affecting the glands need to be seen, or there has to be a complete absence of glands in the biopsies.

Treatment
Treatment of SA focuses on two different aspects of the disease. Firstly, the active inflammatory part of the disease needs to be controlled, if possible. Secondly, the consequences of loss of sebaceous glands have to be limited.

Anatomy of the Sebaceous Gland
The skin contains two layers: the outer epidermis, itself consisting of 5 or 6 layers, and an inner dermis made up of fibers, cells,hair follicles, glands, blood and lymph vessels and nerves. Sebaceous glands are found throughout haired skin and open via a duct into hair follicles

Response to treatment depends on how badly the glands have been attacked, and how many have been affected. If all the glands have been destroyed, then the inflammation goes away, but the effects of this loss will last for life.

The inflammatory (immune response) part of the disease has been treated with several drugs. Steroids are sometimes effective early in the disease process, but can have serious side effects. Cyclosporine, a drug which suppresses the immune system, has been used, but is very expensive and its safety has yet to be proven in the dog. Retinoids, a group of drugs derived from Vitamin A, are also occassionally used. These too are very costly and must not be used in breeding bitches.

The dryness, scaling and resultant coat loss may respond to high doses of essential fatty acids (e.g. evening primrose oil/fish oil combinations). Topical bath oils, emollients, and humectants (conditioners) trap moisture on the skin and hair and may help. Scales can also be reduced by the use of anti-scaling shampoos, although these tend to be drying to the skin. Often a combination of measures is used, although the response can be poor.

SA in the Llasa Apso-Note the hair loss and scaling on the trunk

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http://www.cerebussamoyeds.com/Spring%202001.pdf

The above information is simply informational. It's intent is not to replace the advice of a veterinarian nor to assist you in making a diagnosis of your pet. Please consult with your own veterinarian for confirmation of any diagnosis. Your pets life may depend on it.

Sebaceous Adenitis