Both dogs and cats can suffer from malfunctions of their immune systems when part of the body's system which is supposed to keep your pet safe from invasion by bacteria or viruses actually turns on itself and sees various parts of his own body as 'foreign.' When this happens, the ability of the immune system to recognize the "self" marker is lost, and it begins to attack and reject the body's own tissue as foreign. One specific tissue type such as red blood cells may be affected, or a generalized illness such as systemic lupus may result.
What causes the immune system to short circuit and start rejecting normal body tissue? Many theories exist, but the ultimate answer is, "We don't know." Part of the reason we have modified our vaccination protocol at Fountain City Animal Hospital is because there is some compelling evidence that in certain individuals, the introduction into the body of multivalent modified-live vaccines overstimulates the immune system and can result in an autoimmune episode. Some people believe that environmental pollutants or food preservatives may play a role in the initiation of these terrible syndromes. We do know that genetics plays a role in many species, and we also recognize that some cases seem to occur spontaneously.
No matter what the initiating factors might be, we know that any autoimmune condition is potentially life-threatening and needs an immediate decisive medical response. Your pet might present with Autoimmune Hemolytic Anemia (AIHA) in which the immune system turns on the body's red blood cells and destroys (hemolyzes) them, resulting in an acute and profound life-threatening anemia. Your pet might present with anemia from another type of autoimmune condition, Immune Mediated Thrombocytopenia (IMTP), in which the body destroys one of the main players in the cascade of events that allows clotting of blood in the body. We also see a variety of immune-mediated diseases of the skin including Erythema Multiforme, the Pemphigus complex of diseases, and Discoid Lupus Erythematosis.
The classic example of a multi-systemic autoimmune disease is Systemic Lupus Erythematosis (SLE), also known simply as 'lupus.' Often called the 'great imitator,' lupus can mimic nearly any other disease state. The signs of SLE may be acute (sudden onset) or chronic and are usually cyclic. A fluctuating fever that does not respond to antibiotics is one of the hallmark signs, as is a stiff gait or shifting lameness caused by a classic polyarthritis. Other abnormalities we may find on screening blood work include a hemolytic anemia or thrombocytopenia, or leukopenia (a low white blood count). We often see pain and muscle wasting (polymyositis) and severe damage to the glomerulus, the functional unit of the kidney, which can lead to protein loss in the urine and eventual fatal renal (kidney) failure.
We also see cases of Immune Mediated Polyarthritis, totally separate from the syndrome that constitutes SLE. This is a very painful condition, and dogs usually present to us barely able to move or completely recumbent, in tremendous pain.
Another autoimmune syndrome we have begun to see in recent years is Immune Mediated Meningitis or Encephalomyelitis, both serious conditions affecting the central nervous system.
No matter what the particular body system being attacked might be, a quick diagnosis and initiation of immunosuppressive therapy with high doses of steroids along with other potent drugs as needed is imperative to get these patients immediately comfortable and eventually back on their feet and back to their cozy homes. Many of these patients can be weaned off their immunosuppressive drugs over time, but this must be done with great care and close monitoring.