Dog Hives (Urticaria | welts): Causes, Diagnosis & Treatment

What Are Dog Hives (Urticaria)?

Hives, otherwise known as “urticaria” by medical professionals, are one abnormality you may see. They occur when your dog is allergic to something, such as an insect, medication, or food. Recognizing hives in dogs and understanding the cause is essential to relieving your dog’s discomfort and preventing dog hives in the future.

What do dog hives look like?

• Dog hives look like raised bumps on the skin, usually about the size of a nickel.
• Hives are usually red in color; however, you may not notice redness if they are on a very furry part of your dog. In this case, your pet’s hives may only look like fur-covered bumps. Sometimes, it’s difficult to see the raised bumps, and you may only feel them when petting your dog.
• Dog hives can appear anywhere on the body, including the face, tongue, neck, legs, chest, abdomen, or back. They can affect just one area of the body or the entire body.
• Dog hives are very itchy. This may be the first thing you notice before seeing or feeling hives on your dog’s skin. Your dog will likely be trying to scratch, lick, or bite the areas affected as it will be itchy.
• Hives usually happen very fast– within minutes after exposure to whatever caused them.
• You may notice excessive drooling and a swollen/puffy face if the hives affect your dog’s throat or mouth.

What causes hives on a dog?

Dog hives are almost always related to exposure to an allergen. Once exposed to an allergen, mast cells in your dog’s body release a substance called histamine. Histamine causes blood vessels to dilate, which leads to raised welts on your dog’s skin.

The most common allergens causing dog hives include:

• Insect bite or sting, or ingesting an insect  (photo recommendation: dog playing with bee)
• Vaccinations
• Acute allergic reactions to medications (chemotherapy, vitamin K, antibiotics)
• Food allergies
• Environmental allergies (grasses, trees, mold, dust mites, etc.)
• Contact allergens such as shampoos, insecticides, cleaning products
• Ingesting or skin exposure to toxic plants

Much less common causes of hives in dogs include prolonged exposure to extreme temperatures (hot or cold), strenuous exercise, parasites, or significant psychological stress.

Insect bites/stings, food, and medications are the most common causes of hives in dogs.

How are dog hives diagnosed?

As a pet parent, it can be worrisome to see these skin rashes, but luckily, for your vet to diagnose your dog’s hives. Your vet will use a combination of your history and their physical examination findings.

It’s essential to think about anything new your dog may have been exposed to. Did you see them playing with a bee? Were they recently vaccinated? Did they start a new medication or a new food? During the physical exam, your veterinarian will look at your dog’s skin to evaluate hives and where the hives are located.

If your veterinarian is having trouble diagnosing your dog’s hives or the reason for their hives, they may perform additional diagnostics, such as blood work, skin cytology, skin scrapings, or fecal analysis.

How to treat & get rid of dog hives?

Treatment for hives in dogs can be simple or more extensive, depending on the cause, severity, and duration of the allergic reaction.

To get your dog quick relief from the swelling and itchiness related to hives, your veterinarian will usually administer an injection of diphenhydramine (an antihistamine) and a corticosteroid. Once your dog is feeling better and discharged from the hospital, your veterinarian may also recommend that you continue giving your dog Benadryl two to three times a day at home for a couple of days.

To prevent hives from reoccurring, you need to understand what caused them in the first place so that you can avoid the allergen in the future. If there is no apparent cause for your dog’s hives (such as insect bite, medication, or vaccinations), it may be more challenging to understand how to prevent hives in the future. Environmental and dietary allergies are two possible causes of hives that may require further diagnostics and treatment.

Environmental allergies

If your dog has recurrent hives or has other signs of allergies, your veterinarian may recommend testing for environmental allergies with serum allergy testing or intradermal allergy testing. With these results, your veterinarian can create a plan to desensitize your dog to these allergies with allergen-specific immunotherapy.

If you determine that you cannot eliminate the allergens in your dog’s environment or pursue allergen-specific immunotherapy treatment, your veterinarian may recommend:

• Giving your dog daily antihistamines (such as Benadryl, zyrtec, or hydroxyzine)
• Giving your dog other prescription-strength allergy medications such as apoquel or cytopoint
• Starting daily skin health supplements, such as omega-three fatty acids.
• Frequently bathing your dog with medicated high-quality shampoo

Food allergies

Allergies that stem from food can also cause recurrent episodes of hives in dogs. The most common cause of allergies in dogs include chicken, beef, dairy, and egg 2. Recurrent episodes of hives can also be related to dietary allergies. To diagnose a food allergy, your veterinarian may recommend a diet trial for 6-8 weeks with a prescription food or an over-the-counter diet with a different protein source, like fish or venison. If your dog responds positively to a food trial, you can continue the special diet long term.

Are dog hives dangerous?

Dog hives are rarely life-threatening. However, there are a few less common situations where hives can affect your dog’s breathing and become dangerous.

• Hives in the face, neck, or throat can cause severe swelling that impacts breathing, which can become life-threatening.
• The presence of hives anywhere may indicate your dog is having or about to have an anaphylactic reaction, which causes constriction of airways and difficulty breathing. 3 Besides hives, other signs of anaphylaxis include vomiting, diarrhea, facial swelling, drooling, blue gum color, and collapse.

If you notice that your dog has hives, pay particular attention to how they are breathing and for any other concerning changes in their behavior. If you are concerned your dog may be having severe allergic reactions, take them to the emergency room immediately to rule out a medical emergency.

At-home remedies for dog hives

If possible, take your dog to the veterinarian if you notice they have hives, especially if this is a first-time problem. If your dog chronically or intermittently has hives and the issue has previously been discussed with a veterinarian, some at-home remedies may help relieve the allergic reaction.

• If the hives are not affecting your dog’s face, neck, throat, or ability to swallow, you can administer Benadryl by mouth. Always discuss if this is appropriate for your dog with your veterinarian first and receive instructions about dosage and frequency.
• If the hives were caused by a contact allergen (such as grasses/trees or chemicals) or insect bites you can help relieve itchiness by bathing with a gentle oatmeal-based dog shampoo can help your dog feel more comfortable.
• Apply a cold compress to the hives or the most severely affected areas of your dog’s skin. Be careful never to apply a cold compress for more than 10 minutes at one time, and always wrap the ice or cold object in a towel before applying it to your dog’s skin.