Anaphylaxis is a severe, rapid, whole-body allergic reaction that can cause collapse and death within minutes. Triggers include insect stings, vaccines, medications, and certain foods. The immune system releases a flood of inflammatory mediators that drop blood pressure, constrict airways, and cause swelling. In dogs the liver and gut are major target organs, often producing sudden vomiting and collapse. Emergency treatment with epinephrine and supportive care is required.
Anaphylaxis is the most severe form of allergic reaction, developing within minutes of exposure to a trigger and capable of causing collapse and death. It is a true emergency.
Common triggers include insect stings and bites, vaccines, certain medications, and some foods. The reaction occurs when the immune system overreacts to a substance it has become sensitized to.
Signs come on suddenly and may include facial swelling, hives, intense itching, drooling, sudden vomiting and diarrhea, difficulty breathing, pale gums, weakness, and collapse. In dogs, vomiting and collapse are prominent.
Diagnosis is based on the sudden onset of severe signs following a likely trigger. There is rarely time for testing; treatment is started on clinical suspicion. In dogs, ultrasound may reveal a swollen gallbladder wall, a clue that supports the diagnosis.
Emergency treatment includes epinephrine, intravenous fluids to support blood pressure, oxygen, antihistamines, and corticosteroids, with close monitoring for delayed or recurrent reactions.
Avoiding known triggers, monitoring animals closely after vaccines or new medications, and seeking immediate care at the first signs help prevent severe outcomes.
Animals that have had a severe reaction once are at risk of worse reactions in future and should be seen immediately at any recurrence. Because signs can return after initial improvement, a period of monitoring is advised.This content is for educational purposes and is not a substitute for professional veterinary advice. If you are worried about your pet, contact your veterinarian.
