Dog And Cat Autoimmune Diseases
A reader with a pet named Rosie has asked a question about Rosie’s illness, an autoimmune condition.
Let’s start with the basics of what autoimmune conditions are.
The immune system is charged with the task of keeping us healthy by killing things that invade the body such as bacteria, viruses, cancer cells, parasites, or anything else that can cause disease or damage to the body.
It is when these perfectly normal functions of the immune system go awry that problems occur. The word “auto” comes from the Greek prefix autos, meaning “self.” So, when the immune system begins to attack the very body it is charged with protecting, self, we have an autoimmune disease.
Autoimmune conditions can literally affect any part of the body. The letter presently at hand about Rosie deals with a condition called autoimmune hemolytic anemia, or AIHA. This condition occurs when the immune system determines that red blood cells (RBCs) no longer belong in the body and are targeted for destruction and removal. The result is broken-down red blood cells in circulation, which then have to be removed by the spleen and the components recycled to make new red blood cells. The degree of illness depends on the degree of attack: if only a few RBCs are damaged, neither the patient nor the owner notices. But, when the attack causes the number of RBCs to drop to a point where oxygen-carrying capacity is reduced, the patient becomes sluggish, pants to breathe, and may have yellow skin and red urine. This is truly an emergency crisis.
A cousin condition to AIHA is AITP, autoimmune thrombocytopenia, which is an attack on the platelets of the body. Platelets are fragments of cells called thrombocytes and are very important in the clotting of blood. If platelet production is too low, or platelet destruction or usage is too high, normal clotting fails and bleeding ensues.
The other big category of autoimmune conditions affecting dogs evidences itself in the skin. Conditions such as Pemphigus foliaceous, bullous pemphigus and systemic lupus erythematosus (which can affect nearly every organ of the body, including the skin) are primarily attacks on proteinaceous components of the skin and/or structures immediately under the skin. The lesions usually appear as deep, draining wounds that may be very itchy. The lesions are frequently infected and will not heal without treatment.
There are enough other autoimmune diseases to fill a book. Having covered the most common diseases, we will next look at causes and treatments.
The obvious next question is, “What causes autoimmune conditions?” Here you can get all the way from hard science to conspiracy theories. Let me start by saying that the not all causes of all cases of autoimmune attacks will be identified. When autoimmune disease experts get together, they talk about triggers. Triggers for some patients may be certain foods, certain medications or certain allergens. Some triggers may be “pulled” at birth and just waiting for the bullet to come out. These are patients whose genetic code, most closely linked to breeds and families, puts them at higher risk for an autoimmune attack. They are literally attacks waiting to happen.
Treatment for autoimmune disease is focused on removing the cause or trigger, if it can be identified. Again, since the cause rarely is identified, treatment is usually symptomatic and aimed at suppressing the immune system attack on the affected system of the patient. Many of the drugs are the same as those used in stopping rejection of transplanted organs because rejection, too, is an attack by the immune system on a body part we don’t want attacked. These medications range from common prednisone to exotics like gold salts. Most patients are started on corticosteroids like prednisone, and only those who fail to respond to prednisone get moved up the ladder to more exotic medications. As we move up the ladder, medication cost tends to move up also. However, some of the more exotic medications have fewer side effects.
If your pet is victimized by an autoimmune attack, your pet’s doctor will perform laboratory tests to confirm the diagnosis, begin symptomatic treatment if the condition is advanced and life-threatening, and advise you regarding prognosis and long-term treatment.