Hives (Urticaria) in Dogs

What is urticaria?

Urticaria, also known as hives, is a skin condition characterized by raised red skin welts. Urticaria is commonly caused by an allergic reaction. These swollen welts can appear anywhere on the body, including the face, lips, tongue, throat, and ears. The individual welts can vary in size from about 5 mm (1/4 inch) to several cm in diameter, and if there are a large number of welts, they can blend together. The hives are usually very itchy.

What causes urticaria?

Urticaria is generally caused by direct contact with a substance that causes an allergic reaction. These substances include insect bites, food, pollens, molds, vaccinations, and medications.

Is urticaria dangerous?

If the urticaria is the result of insect stings, particularly bees, dogs can experience dramatic swelling around the face and lips. If the swelling progresses to the throat, breathing can be compromised and result in a medical emergency called anaphylaxis (see handout “Anaphylaxis in Dogs”).

Most cases of urticaria are self-limiting and cause no significant health threat to your pet.

"If the swelling progresses to the throat, breathing can be compromised and result in a medical emergency called anaphylaxis."

Can urticaria be treated?

Yes. Injectable antihistamines and corticosteroids usually bring about a dramatic improvement, sometimes in as little as a few minutes. If your dog develops a rash that goes away without treatment, it is important to report this incident to your veterinarian so it can be noted in your dog's medical records. Dogs that have episodes of urticaria may have other allergic reactions or the episodes may worsen in the future. If the episode is related to vaccination, your veterinarian will modify future vaccination protocols or may pre-treat your dog with antihistamines to minimize this reaction.