What Are the Symptoms of a Dog With Hives?

Allergic reactions can occur in dogs as well as in humans. Allergic reactions in dogs are the result of antibodies that cause inflammatory cells, such as basophils and mast cells, to release substances within the body that cause the reaction. Allergic reactions can occur in any breed of dog, at any age. Hives are a common symptom of allergic reactions and can cause swelling and itching. Hives may appear on the dog's skin as round, raised bumps or the dog's hair may appear to be raised in patches.

  1. Itching and Swelling

    • Itching is perhaps the most common symptom that occurs with hives. A dog that has hives may itch excessively, and have swelling in the affected areas. It is important to watch for excessive swelling, especially around the dog's face and lips. This could be a sign of a serious or life-threatening allergic reaction.

    Urticaria

    • Urticaria is the term used to describe the rapid swelling that may occur with hives. Dogs that have this condition may experience rapid swelling of the lips and eyes, swelling of the neck, and redness of the lips and eyes. Urticaria occurs soon after the dog is exposed to the allergen and is usually treated with an oral antihistamine such as diphenhydramine. The veterinarian may also administer corticosteroids by injection such as dexamethasone or prednisolone.

    Anaphylaxis

    • Anaphylaxis is the most severe allergic reaction that a dog can have. This condition is a medical emergency and many pet owners may not recognize the symptoms of this life-threatening condition until it's too late. Anaphylaxis is characterized by the swift swelling of the larynx (which leads to airway obstruction) and often occurs with hives. Other symptoms of anaphylaxis are itching, vomiting, diarrhea, staggering, weakness, difficulty breathing, rapid swelling of eyes, lips or tongue, and collapse. If your dog experiences a sudden onset of these symptoms, contact a veterinarian immediately for diphenhydramine (an over-the-counter antihistamine) dosage instructions. It is also important to get your dog to an emergency veterinary clinic as soon as possible. The veterinarian may need to administer oxygen and IV fluids, open the dog's airway, and administer medication such as corticosteroids or antihistamines. Anaphylaxis usually occurs quickly after the onset of hives, and while severe, dogs that survive usually return to good health.