When Animals Attack... Themselves

The immune system is a fabulously intricate apparatus that provides a defensive barrier between our delicate insides and the comparatively filthy outside world. Millions of microscopic warrior cells are quartered in strategic points all over the body, and each camp communicates with the others using floods of particles which are even tinier. Upon arrival, those minute communication particles bind to the outer surface of the recipient cell. A detailed message is delivered into the interior; new products are synthesized, and quickly. More messages go out. The result is an orchestrated response of tiny, angry defenders equipped with the weapons to immobilize, dismember, and remove invaders--from the size of a virus right on up to the relatively enormous dimensions of a splinter or even a parasitic worm.

The whole thing has to be in pretty good working order all the time, because every surface we touch, even everything we put into our mouths, is crawling with germs and other contaminants. Every so often, however, the immune system gets... a screw loose. Somewhere along the line, one of those carefully devised bulletins is somehow lost in translation. Instead of completing its duties as assigned, the army loses sight of exactly who's the boss and who's the enemy. It actually begins to attack the surfaces of the body and turn that vicious arsenal of weapons against itself. This is known as autoimmune disease, and it's actually relatively common in dogs and cats.

In hemolytic anemia, red blood cells are abducted from the bloodstream and vaporized. Lose enough of these, and oxygen can no longer be carried to the distant points of the body. I don't need to tell you what happens then. In other cases, it's not red cells but platelets under attack. When too many platelets have been destroyed, blood just starts to spontaneously seep out of the vessels (gruesome, I know), causing bruises, nosebleeds, strokes, and other forms of blood loss. Another type of autoimmune disease targets the skin, causing blisters, rashes, and scaling on various surfaces of the body. This initially only causes itching and discomfort, but it can expand to damage multiple joints and major organs like the kidney.

We're not yet sure how a previously reliable immune system can become so unstable that it begins to demolish its own home. Furthermore, today's technology doesn't allow us to identify and smother the specific courier that's causing the problem. In most cases, the entire defense mechanism needs to be shut down and rebooted in order to prevent the patient from killing himself. We often have to take the immune system off line for several weeks to months. During that time, we earnestly hope it will abandon its deranged attempts to self destruct. While on this type of therapy, the body is very vulnerable to infections and to side effects of the medication itself, which can be quite severe. That's a fine line to walk, but many of our patients do emerge safely on the other side of this complex disease.

Dr. M.S. Regan