Why Does My Dog Have Welts All Over His Body?

Updated on May 30, 2016
Dog welts all over body
Dog welts all over body
Welts in dog
Welts in dog

What are Welts in Dogs?

Urticaria is the medical terms used to denote the presence of welts, also known as wheals or hives on a dog's skin. The skin rash presents with raised, red itchy bumps that typically cause a burning and itchy sensation. The welts can be localized on the dog's head, legs, belly or back or they can be widespread all over the dog's body. They may tend to come and go. Some dog owners describe the welts as appearing as dime sized bumps on the dog's skin.

While there are many causes of welts in dogs, they often tend to appear as a result of an acute (arising suddenly) allergic reaction. A common culprit can be vaccinations, which is why vets often recommend keeping an eye on the dog for the first few hours after receiving shots. Other causes are allergic reactions from exposure to certain types of plants, insect bites, household chemicals, medications, stress and foods. In some cases, the presence of welts may be indicative of medical conditions. This article will focus mainly on welts triggered by allergic reactions.

When it comes to allergic reactions, welts can form when there is direct contact with an irritant. In this case, it's called "contact dermatitis" and the allergic reaction is mostly localized to the area that got in contact with the allergen. The welts or rash will therefore show up often on dog feet and the belly area if the dog happens to lie down on the product. Inhaled allergens such as grass pollen, dust mites or mold can also cause welts.Insect bites can also be a culprit if the dog is allergic to them. However, some times, the actual trigger may be difficult to pinpoint and the underlying cause of the welts on dog skin remain a mystery. A veterinary dermatologist may test for some common allergens, but the process can be costly and challenging at times.

What Causes Welts?

When the dog's immune system reacts to an allergen, mast cells in his bloodstream release the chemical histamine. Histamine triggers small blood vessels under the dog's skin to leak. The accumulated fluid therefore forms large welts.

A Risk for Complications

One concern about welts is that they can sometimes be accompanied by swelling of the lips, nose and eyes (angioedema). Sometimes the eye swelling is so severe, the dog cannot open its eyes. These cases may require antihistamines and injectable steroids, but serious cases may sometimes spread to the throat (laryngeal edema) which can block the dog's airway and lead to anaphylactic shock. Other accompanying symptoms may include generalized symptoms such as vomiting, abdominal pain, diarrhea, shock, pale gums, cold legs, incoordination, collapse, convulsions, and death.

Time is of therefore of the essence here. According to the Merck Veterinary Manual dogs can die from anaphylaxis within minutes. These dogs need immediate vet attention for a shot of life-saving epinephrine. And for those curious to know, yes, they do make epi-pens for dogs!

Respiratory distress can occur if the angioedema involves the nares, larynx, or pharynx.

— Karen A. Moriello, DVM, DACVD

Treatment for Welts in Dogs

In order to address welts in dogs, the underlying allergy needs to be addressed. Benadryl, is an anti-histamine which can help provide relief, as it blocks the release of histamine. According to veterinarian, Dr. Christine M, plain Benadryl (diphenhydramine) can be given at a dose of 1 mg per pound of body weight, every 12 hours until the dog's symptoms are gone. It's always best to consult with a vet before giving Benadryl to dogs and to discontinue its use should the dog show behavior changes such as excitement or lethargy. Benadryl should not be given to dogs suffering from glaucoma. Other medications given under vet prescription include Claritin (loratidine) and Atarax (hydroxyzine) given under the dosage and guidance of the vet.

Omega 3 fatty acids are also beneficial for the skin, but may take some time to kick in and provide relief. Veterinarian Dr. Kara recommends combining fatty acids and antihistamines as they appear to work in synergy, increasing their effectiveness compared to when either one is given alone.

Frequent bathing under the form of cool water baths may provide relief to minimize the time the allergen is in contact with the skin as in the case of dogs allergic to pollen and grass which accumulates on the skin. Oatmeal baths are soothing for dogs with allergies.

If the vet suspects the welts derive from a food allergy a special hypoallergenic diet may be recommended. This means no more table scraps or treats as the diet needs to be fed exclusively. Common prescription diets often contain novel proteins the dog has not been exposed to before and these diets need to be fed for at least 2 to 3 months or more for the effects to be seen.

Sometimes when dogs have rashes, the constant itching and scratching may cause lesions that cause secondary bacterial or yeast infections and dogs may require also a course of antibiotics. A vet will need to diagnose these secondary skin conditions though through a skin scrape. These secondary infections are often treated with antifungal or antibacterial shampoos such as chlorhexidene shampoo for bacterial infections and Malaseb for antifungal.

For severe reactions, steroids are sometimes given under the form of a shot or oral medication ( like prednisone) but these drugs can have annoying or severe side effects at times and they work by suppressing the immune system.. In some cases, the dog may develop welts again once the steroid is out of his system.

Disclaimer: this article is not meant to be used as a substitute for veterinary advice. If your dog has welts, please see your vet.


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    • profile image

      Gina Auton 4 months ago


    • profile image

      Jenny 10 months ago

      Thank you. Helpful article!

    • alexadry profile image

      Adrienne Janet Farricelli 19 months ago from USA

      Thanks all! This is important information to be aware of as dogs can be prone to allergic reactions and welts in dogs may not be readily identified as they look different than welts in humans.

    • DDE profile image

      Devika Primić 19 months ago from Dubrovnik, Croatia

      I like the way you write about our friendly pets. Informative and always useful.

    • Karen Hellier profile image

      Karen Hellier 19 months ago from Georgia

      Interesting article. I have never noticed welts on my dog's body but she is 11 and has had hot spots and fatty tumors. Thanks for this information though. Very thorough article.

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      stella vadakin 19 months ago from 3460NW 50 St Bell, Fl32619

      Very interesting article and good advice. I have always used benadryl for my dogs. I am lucky my smaller dogs do not seem to get much of anything.

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