Autoimmune Skin Disease (AISD)
AISD results from a disorder of the immune system and the skin. Normally the immune system only attacks "foreign" invaders (bacteria and viruses). In AISD, the animal's body recognizes its own skin as "foreign". As a result of this abnormal immune response, the skin is attacked and damaged. In a sense, the animal is trying to reject its skin, just as it would try to reject a viral or bacterial infection.
Why does the animal's immune system recognize its own body as foreign? So far, we can't answer that question. Various explanations have been proposed which include genetic, environmental, drug and viral factors. In dogs, there is some evidence for a genetic component, as AISD is seen more commonly in certain breeds (Akitas, Collies, Shelties, Chows and Dobermans). We currently diagnose several distinct syndromes, eg. Pemphigus, pemphigoid, systemic and discoid Lupus Erythematosus.
Most cases of AISD occur in mature animals. The skin lesions first appear as small red spots that rapidly form a blister, then a pustule or pimple, and finally a crust. In most cases, the major lesions noted by the owner are red spots, ulcers and thick crusts (scabs) that form over the spots. The crusts usually start on the nose, around the eyes and on the ear flaps. Lesions may also involve the foot pads, mouth, anus and genitals. Itchiness is variable, as some pets are not bothered at all while others are rubbing and scratching. Other signs noted are depression, lethargy, anorexia, lameness, enlarged lymph nodes and fever.
Several tests are necessary to diagnose AISD. Blood tests along with cultures and skin biopsies are needed to diagnose if, and which, AISD is present.
Once the diagnosis has been made, several treatments are available. Treatment involves using different medications that suppress the abnormal immune response and therefore are called immunosuppressive drugs. Each drug available has its good and bad points. They are all very potent agents and can cause serious side effects with chronic use. A baseline blood panel and urinalysis will be done initially and periodically during treatment to monitor for adverse drug effects.
In most cases, pets with AISD can be controlled so that their skin is normal with only rare flare-ups. However, most have to stay on some treatment for life. In addition, there are some cases that can't be controlled with the treatments currently available. At the present time there is not test to determine which dogs will respond to treatment and which ones will not. It may be necessary to try several different drugs or combinations of drugs before you will know whether or not your pet's disease can be controlled.