Anaphylactic Shock in Dogs

Dog being examined by a veterinarian on an exam table.
Anaphylactic shock requires immediate veterinary attention.

Getty Images/Monty Rakusen 

Anaphylactic shock is a severe form of a hypersensitivity or allergic reaction to an allergen. This type of reaction can be life threatening if not treated immediately. Knowing how to be recognize the signs of anaphylactic shock could potentially save your dog's life.

What Is Anaphylactic Shock in Dogs?

Hypersensitivity reactions can occur when a dog is exposed to an allergen. Reactions can be localized on the external surface of the body (i.e. skin) or systemic and cause life threatening consequences due to multiple organ system involvement. Anaphylactic shock is the systemic form of a type 1 hypersensitivity reaction. Also known as anaphylaxis, it is an overreaction of the dog's immune system to an allergen and is thought to even have a hereditary or familial reason for occurring.

In response to exposure to an allergen, an exaggerated immune response occurs leading to the release of histamines. If localized to the skin, it causes the redness and itching, hives, and/or facial swelling.

But in anaphylactic shock, the excessive amounts of histamines in the body lead to decreased blood pressure, smooth muscle contraction, capillary dilatation, and edema. In many animals, the lungs are most affected by anaphylactic shock causing respiratory distress, but in dogs, the liver is the main organ compromised by this reaction. Due to its close relation to the gastrointestinal system, dogs with anaphylactic shock can quickly develop diarrhea/bloody diarrhea, vomiting, drooling, pale gums, cold extremities, and collapse. Pale gums and cold extremities are indicators of poor circulation. Poor circulation in your dog can progress to collapse or coma, so seek veterinary treatment immediately.

Signs of Anaphylactic Shock in Dogs

  • Diarrhea
  • Vomiting
  • Drooling
  • Skin-related symptoms (hives, itching, swelling)
  • Pale gums
  • Cold legs
  • Collapse
  • Coma

Causes of Anaphylactic Shock in Dogs

Any exposure to an allergen or antigen can result in anaphylactic shock if a dog is severely allergic to it but the following things are the most commonly seen types of allergens.

  • Insect stings: Wasps, fire ants, and bee stings usually just cause redness and swelling at the sting or bite site but if a dog is severely allergic to them, anaphylaxis may occur.
  • Medications: If your dog has an allergy to a medication, anaphylaxis can occur.
  • Vaccines: Similarly to medications, some dogs can react negatively to vaccines. Vaccines have different ingredients in them that may cause anaphylaxis in dogs.

Treatment of Anaphylactic Shock in Dogs

Immediate veterinary treatment of anaphylactic shock is needed to prevent serious complications such as seizures, coma, and death. Treatment often entails fluid therapy to address poor circulation and dehydration from vomiting and diarrhea, medications to counteract the body’s reaction to the allergen, and oxygen. Additional treatments are often administered to address nausea and other symptoms that may develop. 

How to Prevent Anaphylactic Shock in Dogs

If you know that your dog has allergies, then the best thing you can do to prevent anaphylactic shock is to keep your dog away from that specific allergen. If you don't know what your dog is allergic to, monitor it closely when it is exposed to medications and vaccines to ensure there are no signs of anaphylaxis. And, avoid exposing your dog to ant hills and stinging insects as best you can while outside.

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  1. Disorders Involving Anaphylactic Reactions (Type I Reactions, Atopy) in Dogs. Merck Veterinary Manual.

  2. Anaphylactic Shock: How to Effectively Diagnose and Treat. Today's Veterinary Practice.