Introduction

Anaphylaxis is an unusual or exaggerated allergic reaction (called “hypersensitivity”) to a foreign protein or some other foreign substance, such as a drug or toxin (these are called “allergens”). Anaphylactic shock refers to the serious and generalized state of shock brought about by this hypersensitivity and is the end result of a severe anaphylactic reaction. If not treated quickly, anaphylaxis can cause rapid and devastating consequences, up to and including death. There are innumerable causes of anaphylactic shock in dogs, depending upon the particular animal’s immune system.

Causes of Anaphylactic Shock

Vaccinations

Virtually any agent can cause anaphylaxis, depending on whether the dog is allergic to it or not. Vaccines are commonly reported to cause allergic reactions. While most vaccination reactions are mild and only cause a slight fever or lethargy, some dogs can have an abnormally strong and sudden reaction to a vaccine which results in anaphylactic shock. Any type of vaccine, including modified live and killed virus vaccines, has the potential to cause an anaphylactic reaction. However, it is extremely rare for dogs to suffer from anaphylactic shock as a result of vaccines.

Allergic Reactions

A more common cause of anaphylaxis in dogs is an allergic reaction to medication. Just like in people, dogs can have an allergic reaction to almost any drug or substance not normally found in their bodies, including for example penicillin. Other potential causes of anaphylaxis include topical flea and tick treatments, insect stings, venomous bites, oral or topical antibiotic products, local or general anesthetics, drugs prepared from animal products (like insulin, adrenocorticotropic hormone and enzymes), diagnostic agents (such as iodinated x-ray contrast media), mold, pollen and particular ingredients in food.

Once a dog experiences anaphylactic shock from exposure to a particular allergen, that allergen usually will continue to cause severe allergic reactions upon reexposure.