Dog Skin Allergies: What to Know

Is your dog suddenly scratching more than ever before? Dog skin allergies are one possible reason behind canine itchiness. Here’s what to know about skin allergies in dogs.

What Causes Skin Allergies in Dogs?

Also called allergic dermatitis, skin allergies are the most common type of allergic reactions in dogs. There are three major causes of skin allergies in dogs: fleas, food allergies, and atopic (or environmental) allergies.

Types of Dog Skin Allergies

Flea Allergy Dermatitis in Dogs

Flea allergy dermatitis is an allergic reaction to flea bites. Some dogs are allergic to flea saliva. This makes affected dogs extremely itchy, especially at the base of the tail, and their skin may become red, inflamed, and scabbed.

Dermatitis from fleas is the easiest to treat. In these cases, the dog reacts to saliva injected into the skin as the flea feeds. It’s like having mosquito bites all over you.

The key with this type of allergy is that the itch is more intense over the tail head. You usually see fleas, or you may find flea dirt, which looks like black pepper on the skin surface. Vets typically treat flea allergy dermatitis by applying a product that kills fleas before they bite.

Food Allergies in Dogs

Food allergies and sensitivities can cause itchy skin, as well. Dogs dealing with food allergies often are itchy around the ears and paws. Gastrointestinal issues may appear, as well.

There are several possibilities for why food allergies develop. Some dogs have a genetic predisposition to developing allergies. The same holds true for atopic allergies.

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The other contributing factor to food allergies is constant exposure to the same ingredients. For example, if you have continually fed a lamb and rice diet, continued exposure to those ingredients can cause intestinal inflammation and “leaky gut syndrome” (where the antigen is absorbed through the gut lining). The reaction appears in the skin, creating itchiness.

Talk to your vet about whether rotating foods in your dog’s diet can help prevent them from developing allergies. Foods that commonly trigger dog skin allergies include grains (like corn, wheat, rice, barley, and oats) and chicken.

However, true food allergies may not be as common as people think, according to Dr. Jerry Klein, Chief Veterinary Officer for the AKC. True food allergies result in an immune response, which can range in symptoms from skin conditions (hives, facial swelling, and itchiness), gastrointestinal signs (vomiting and/or diarrhea) or a combination of both. In some rare cases, a severe reaction resulting in anaphylaxis can occur, similar to severe peanut allergies in humans.

The best way to diagnose and treat a food allergy is to work with your veterinarian to manage your dog’s symptoms and discover which ingredient may be causing the reaction.

Environmental Allergies in Dogs

Environmental allergens, such as dust, pollen, and mold, can cause atopic allergic reactions or atopic dermatitis. In most cases, these allergies are seasonal, so you may only notice your dog scratching during certain times of the year. As with food allergies, the most commonly affected areas are the paws and ears (but also include the wrists, ankles, muzzle, underarms, groin, around the eyes, and in between the toes). Dogs often scratch their ears or lick their paws.

There is some debate about how these allergens cause itchiness. The traditional theory is that your dog may inhale them, then these allergens proceed through the lungs into the bloodstream, eventually finding their way to the skin. The other possibility is that they settle on the skin and migrate between the skin cells to the lower skin layers (the dermis). Either way, an allergen reacts with an antibody, which triggers the release of a histamine, causing itchiness.

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Your vet may diagnose atopic allergies with intradermal skin testing, where allergens are injected into the skin to look for reactions. They may also treat atopic allergies with medication (such as canine antihistamines, cyclosporine for dogs, or prednisone for dogs) and also with allergy injections (hyposensitization).

With all dog skin allergies, there is the risk of secondary infection. As your dog scratches, bites, and licks at their skin, they risk opening up their skin to yeast and bacterial infections that may require treatment.