Our immune system is a remarkable network of communicating cells that helps our body fight the daily influx of bacteria, viruses and fungal organisms. We are able to live in a non-sterile world with billions of cohabitating bacteria in our gut and not succumb to infection. Researchers continue to consider ways to use the immune system to fight cancer while HIV demonstrates the effects of a broken one. Sometimes the immune system makes mistakes- it takes what should be recognized as “self” and turns it into the enemy.
Auto-immune disease is a catchall term for when the immune system misfires and focuses an attack on the “good guys” (our own cells) in our bodies. Antibodies are small proteins that normally label foreign material and bacteria for destruction. If a patient receives a transplant organ, then special medication needs to be given to help prevent that patient’s body from rejecting the new tissue by developing antibodies to the unique transplant protein. Veterinary patients also develop these self-destructive diseases where vital systems may be attacked. Red blood cells that carry oxygen, platelets that allow blood to clot and blood vessel lining cells are just some of the body parts that can be affected by auto immune disease. Antibodies can develop against receptors between the nerves and the muscles rendering a patient unable to walk and swallow in a disease called myasthenia gravis.
We often don’t know why these diseases develop. Some think there is a correlation between receiving vaccines (a stimulus to the immune system) or certain medications that might trigger the misfire that creates an autoimmune disease. Animals that have immune mediated hemolytic anemia can lyse their red cells over days or in severe cases hours- creating a medical emergency as the oxygen carrying cells are destroyed and inadequate delivery of oxygen creates a life threatening illness. In the case of platelets being the target, those patients may bleed into their lungs- creating the inability to breathe, their intestines may undergo massive blood loss, or the brain may experience severe neurologic damage. In each case prompt care to suppress the immune system is needed to prevent irreversible damage. You can read more about the many autoimmune diseases at this link.
http://www.provet.co.uk/petfacts/healthtips/autoimmunedisease.htm
Therapy is focused on decreasing the production of antibodies-usually by reducing the number of antibody producing cells such as lymphocytes. The aim is also to decrease the ability of the faulty antibodies to attach to the targeted proteins particularly because in these cases the proteins are part of “self” not “other”. This helps slow the process of destruction of the cells and the damage to certain parts of the body. Prednisone is one of the first line medications with cyclosporine, mycophenylate, leflunomide and in some cases intravenous gamma globulin (Privigen) to block the receptors for erroneous antibodies. If massive blood loss or rapid hemolysis of red cells are present survival rates are often less than 50%. A lengthy hospital stay or treatment period may be needed with prognosis remaining unclear for a week to 10 days in many cases.
Prevention of auto immune disease involves monitoring your pet and creating a carefully thought out vaccination protocol with the guidance of your family veterinarian. Be sure pets are protected from common infectious diseases, based on their lifestyle, and that they have additional vaccines to protect from illness, but not more than necessary. Many people are choosing to run vaccine titers on their pets. A blood test can confirm the presence of adequate antibodies to certain viruses- distemper, parvo virus and Rabies in order to avoid unnecessary administration of additional vaccines. The best prevention for any illness is close careful observation and regular interaction to know the attitude, energy and personality of your pet, so changes are apparent when they occur.
Blog Post Author:
Merrianne Burtch, DVM, DACVIM