Causes of Anaphylaxis in Dogs
There are countless potential causes of anaphylactic shock in dogs, depending upon the particular animal’s immune system. The inciting allergen may be saliva from an insect bite, venom from a snake bite or a bee sting, a particular medication, topical parasite treatments, an environmental allergen (mold, pollen, grasses, chemicals, dust, etc.), some component of the dog’s diet, a vaccine or virtually anything else. The substance, called the allergen, is perceived as foreign and harmful by the dog’s immune system. Initial exposure to the allergen – which can be by physical contact, inhalation or ingestion - produces a cascade of immunological changes that essentially put the dog’s body on heightened alert to any subsequent exposure to the same allergen. Upon re-exposure, these mobilized components of the dog’s immune system aggressively activate, synthesize and release what are collectively called “inflammatory mediators.” Within a matter of minutes, the situation can become critical. The inflammatory mediators cause dilation (stretching beyond normal dimensions) of the blood vessels, increased leakiness (permeability) of the blood vessel walls, dangerously low blood pressure (hypotension), respiratory abnormalities, accumulation of fluid in the throat, excessive secretion of substances into the airways, heart rhythm disturbances, gastrointestinal distress, severe itchiness (pruritis) and widespread pain.
Prevention of Anaphylaxis in Dogs
The best way to prevent anaphylactic shock is to avoid exposing a dog to any substances that it is known to be allergic to. Of course, this is only realistic after the dog has had an allergic reaction to something, and even then only if the offending allergen can actually be identified. Intravenous medications should be administered slowly to reduce the chances of an anaphylactic reaction to the medication.
Once a dog suffers anaphylactic shock from exposure to something in its environment, that allergen usually will continue to cause severe allergic reactions when the dog comes into contact with it again. Occasionally, a dog may go into anaphylactic shock on the very first exposure to an allergen, although it is much more likely to go into anaphylaxis on a second exposure.