Hives in Dogs | Symptoms of Hives in Dogs | Allergic Reaction in Dogs

By Jessica Remitz

Hives (Urticaria) and a swollen face (Angioedema) are commonly the result of an allergic reaction in dogs. Similar to humans, when a dog is exposed to one a particular allergen, the immune system reacts—or in most cases, overreacts—and causes a hypersensitive state. Hives in dogs are usually not life threatening, but it is important to seek veterinarian care as soon as possible to treat the condition.

Causes of Hives in Dogs

“There are many different allergens that can cause hives,” says Yvonne Szacki, DVM of Park Slope Veterinary Center in Brooklyn, New York. Common causes of hives or swelling of the face include:

– Insect stings or bites, including bee stings and spider bites.

– Vaccines, primarily following an injection of a vaccine, like rabies or Bordetella (also known as Kennel Cough). 

– Food allergies.

– A chemical reaction, primarily to insecticides used to treat grass.

– Plants, including poison ivy or oak.

– According to renowned veterinarian and medical journalist Dr. Jeff Werber of Los Angeles, California, “Nearly any allergen that your pet is hypersensitive to can cause hives.”

Signs and Symptoms of Hives in Dogs

“The degree to which a pet suffers from hives depends on what the irritant or allergen is and the degree to which your pet is affected by it,” Werber says, adding, “Two dogs can be exposed to the same allergen and have extremely different reactions from each other.”

Symptoms of hives in dogs can include:

– Medium to large areas of redness and swelling on the face, abdomen, and legs.

– Swelling around the muzzle.

– Swelling around the eyes, which can cause them to close.

– Excessive scratching.

– Drooling, if the muzzle starts to swell.

Similarly to humans, a dog’s skin will often break out in raised, circular lumps and bumps, “But the reaction can become more severe if left untreated and could lead to a dog’s throat closing,” Werber notes.Because hives are so itchy, your dog may begin scratching excessively, which can also make the reaction worse. “The more the animals is reacting, the more they start scratching themselves and contribute to the trauma of the skin,” Werber says. “Think of it as getting terrible mosquito bites then scratching them all at once—it makes it worse than the bite was in the first place.”

Treatment for Hives in Dogs

Hives are generally treated with the appropriate dose of antihistamines, such as Benadryl or a steroid, depending on the severity of the reaction. It is not uncommon for the hives to resolve on their own once the allergen has moved through the body, but, according to Szacki, “[It] can take between 24 and 72 hours to clear.” Weber advises that, “Using ice or a cold towel to soothe your dog’s skin can also help them to feel better and limit excessive scratching.”

For first-timers, Werber recommends seeing a veterinarian immediately, as failure to treat hives can lead to a more serious reaction as the allergy progresses to other parts of the body.  Pet parents that have dealt with hives before may be able to manage the condition from home, depending on if their dog has been exposed to the same allergen twice and they have instructions from their veterinarian. If you are administering Benadryl from home, Werber suggests administering one milligram per pound.

How to Prevent Hives in Dogs

“The best way to prevent a recurrence of hives in your pet is to avoid exposing your dog to the allergen that caused the reaction and to keep Benadryl on hand at home,” Szacki says.

Werber adds, “If you have identified what your pet has reacted to in the past, particularly for a reaction to a vaccination, you can also pre-treat for the condition. With a reaction to a vaccination, you can give the dog a shot of Benadryl prior to the vaccination, wait 10 to 15 minutes, and then safely give them the injection.”

Fortunately, most cases of hives in dogs are just allergic reactions, so there’s no need to panic if your canine does have a breakout. Just be sure to see a veterinarian and follow their advice for appropriate care.