Autoimmune Disease in Dogs and Cats Explained

Autoimmune Disease in Dogs and Cats

A normal immune system functions to remove foreign or invading substances such as bacteria or viruses, by targeting them for destruction and systematically removing them.  The immune system is comprised of a complex network of tissues specialized to create and mobilize white blood cells and other complex immune cells in concert with regulatory proteins and biochemical mediators to carry out the immune system’s search and destroy mission to rid the body of foreign invaders.  Autoimmune disease refers to a class of diseases whose cause stems from the immune system functioning abnormally to mediate the attack of its own tissues.

Autoimmune disease can be present in just about any organ system of the body, where an abnormally functioning immune system can destroy certain integral cell lines of the body , as in the case of immune mediated hemolytic anemia, or attack its own tissues, as in the case of chronic active hepatitis.  Other autoimmune diseases target the gut, as in the case of inflammatory bowel disease, while still others target the central nervous system.

What causes autoimmune disease?

Autoimmune disease is by in large genetic, where inherited abnormal genes are responsible for creating a dysfunctional immune system capable of mistaking its own tissues for and invading or foreign substance.  Exceptions to this rule are circumstances where disease intervenes to create abnormal tissue morphology that facilitates the immune system targeting the tissue for attack.  Certain cancers can be responsible for this, as can certain infectious diseases, such as tick born bacterial infections.  That stated, most cases of autoimmune disease are genetic in origin.

Do vaccines cause autoimmune disease?

No.  It has become a popular topic among internet chat forum people, some breeders, groomers, and other non-medically people that work in the pet industry that pet vaccines are a major cause for autoimmune disease in dogs and cats.  The reality, however, is that the link to vaccines causing autoimmune disease is at best thin.  While it is true that vaccines can trigger or exacerbate autoimmune disease in a patient already genetically predisposed to it, they are not the cause.  As such, attempts to prevent autoimmune disease by not having pets immunized are both misguided and dangerous, leaving pets susceptible to deadly infectious disease when the main determination of whether or not a pet will develop autoimmune disease lies in its genetic code.

That stated, in a patient with known autoimmune disease vaccines whose protective properties stem from their ability to stimulate the immune system into creating protective antibodies against a given infectious disease, vaccines could aggravate existing disease.  Therefore, in patients with known existing autoimmune disease, it is best to administer vaccines minimally, focusing more on reducing risk through lifestyle adjustment and trying to gauge the necessity for vaccine administration on protective antibody titers.  While protective antibody titers are far from a fool proof measurement of disease preventability, they still offer some value for patients that have diseases that can be exacerbated by vaccines.  (Click here for more on vaccine titers)

Does feeding grains cause autoimmune disease?

No.  While some grains, such as wheat have the potential to cause food allergy, which technically is a form of the immune system over-reacting or acting inappropriately, allergy and autoimmune disease are very different.  With an allergy the immune system responds to a false alarm created by a harmless substance it has mistaken as a threat.  In the case of autoimmune disease, the immune system’s recognition apparatus breaks down, and the body begins to manufacture T cells and antibodies directed against its own cells and tissues.

Can I prevent autoimmune disease in my pet?

In most cases with genes driving most predilections to autoimmune disease, the answer is in most cases, no.  However, decreasing the risk of infectious diseases known to trigger autoimmune disease can help to minimize some risk.  Keeping your pet healthy through good nutrition, good preventive well care, husbandry, and overall minimizing their potential to contract infectious disease that are known to trigger autoimmune disease is therefore a good idea.

Keeping cats indoors and decreaseing potential exposure to the blood parasite hemobartonella, for example, an infection known to trigger immune mediate destruction of red blood cells leading to life threatening anemia, would help to decrease their potential for autoimmune disease.  With flea bites suspected to be a major vector for the transmission of bartonella felis, a bacteria linked to autoimmune stomatitis, a disease that leads to painful infections and ulcerations of the gums and other mucus membranes of the mouth of cats, monthly flea prevention could go a long way toward preventing the disease.

In dogs, certain tick born bacterial diseases are linked to autoimmune disease, making limited exposure to ticks and/or comprehensive tick prevention an important way to reduce risk of autoimmune disease being triggered by infection.

Dr. Roger Welton is the President of Maybeck Animal Hospital and CEO/Chief Editor of the veterinary information and blog online community, Web-DVM.