A Closer Look at Canine and Feline Anaphylaxis

Rebecca Dablow, CVT

Associate Veterinary Information Specialist

Anaphylaxis is a sudden, often unexpected reaction of the immune system in response to an antigen.  This reaction can quickly become a medical emergency and it’s important to know the signs to watch for so you can respond appropriately, and ensure your pet receives the appropriate veterinary intervention.

An antigen, or allergen, may be anything your pet is exposed to which creates an immune response within the body. Common antigens include insect or reptile venom, medications and vaccinations, foods (such as peanuts in humans), plants, and other toxins.

A mild to moderate immune response or allergic reaction in our pets may include a runny nose, watery eyes, itchy or irritated skin, digestive upset, reddened skin, hives, and facial swelling (which is often what our owners call to report)

Anaphylaxis occurs when the symptoms move beyond this, to a more urgent concern.  We can see signs progress to airway obstruction, cardiac changes (arrythmias and decreased blood pressure leading to shock). Extreme cases may lead to cardiac and respiratory arrest, followed by death.

If any early signs are seen in your pet and you think they may be having a possible allergic reaction, please call your veterinarian right away to triage the situation and gauge urgency.  Your veterinarian will often treat this type of reaction with injectable and/or oral steroids and antihistamines. Severe cases may need hospitalization, aggressive supportive care, and the use of epinephrine (adrenaline).

Sometimes, we never find out what the original antigen is, and the experience is a one-time event.  In other cases, we can isolate the exposure if it occurred within a few hours of the symptom onset.  Your veterinarian may recommend consulting with Pet Poison Helpline in the event of anaphylaxis, as there may also be a concurrent poisoning or toxicity concern.  We are here 24 hours at to assist both pet owners and veterinary professionals.