Spring is wonderful for outdoor activities for you and your pet but can result in exposure to bees, wasps, hornets, ants, and other biting and stinging insects. Most of us know these bites and stings can cause an allergic reaction in people. Did you know these allergic reactions are just as common in our pets and can occur in dogs of any age, breed, or sex? Reactions can vary from mild to severe.

Mild. Pets that have a mild reaction will have minimal swelling or pain where they were stung. Your pet may or may not require treatment but monitoring for worsening symptoms is strongly advised.

Your pet may not develop allergic symptoms right away so it’s a good idea to call your veterinarian and have a plan should things worsen.

Moderate. This is the most common reaction in dogs. Pets with moderate allergic reactions often will have urticaria.  Urticaria is a moderate vascular reaction of the skin marked by hives or wheals and rapid swelling and redness of the lips, around the eyes, and in the neck region.  It is usually extremely itchy.  Urticaria may progress to anaphylaxis and is considered life threatening.

Severe. The most severe reaction is anaphylaxis, a sudden, severe allergic response that produces breathing difficulties, collapse and possible death. Symptoms usually occur within minutes following an insect bite or sting and proceed rapidly.  Symptoms usually include sudden onset of vomiting, diarrhea, staggering, rapid drop in blood pressure, swelling of the larynx leading to airway obstruction, seizures and cardiovascular collapse or death. This reaction is life threatening for your dog. Antibodies that the immune system has made to some portion of the insect venom trigger anaphylaxis and urticaria.

It is important to note that in the most severe reactions I’ve seen, the owners never suspected a bug sting. They called our hospital because their dog was vomiting, lethargic or had diarrhea.

There is no diagnostic test for anaphylaxis or urticaria.  However, there is a study in progress here in Southern California that is looking at the relationship of a liver enzyme called Alanine Transferase (ALT) and insect envenomation.  It seems when this enzyme is elevated after an insect sting, prognosis goes down for the dog and more aggressive treatments are needed. Your veterinarian may want to check this enzyme if an insect sting is suspected.
Treatment in mild cases can include oral diphenhydramine (Benadryl) however, call your veterinarian for proper dosing.  Treatment for a moderate reaction involves a trip to the hospital for evaluation and will usually include injections of cortisone and other medicine. Treatment for a severe reaction is critical and your pet should be taken to a hospital as soon as possible. Minutes count. Severe reaction treatments may include i.v. medication, such as epinephrine and fluids, as well as oxygen and other life supporting procedures.

NOTE:  Giving oral antihistamines, like Benadryl, in an acute, severe reaction is usually ineffective and can be dangerous. These animals need to be transported to a veterinarian immediately.


There is no way to prevent or predict these allergic reactions, so it is important to have a plan and be prepared. Put your veterinarian’s phone number, as well as the after-hours emergency clinic that your veterinarian recommends when they are closed, on your cell phone.

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