Dr. Terri Bonenberger, DVM, authored this article.
Just as allergies are increasing among humans, veterinarians are also seeing significant increases in allergies in dogs. Interestingly, the symptoms of canine allergies cause different symptoms than typical “hay fever”—known clinically as allergic rhinitis in people. While people sneeze and wheeze, dogs tend to itch and scratch!
What to Watch For
Consider speaking with your veterinarian about allergies if your dog suffers from:
- Seasonal or non-seasonal itching, licking, scratching, rubbing
- Foot licking, face rubbing/scratching
- Rashes or patchy areas of redness
- Recurrent ear infections or head shaking
- Recurrent skin infections
- Patchy hair loss
Canine Allergies: Many Forms
Canine allergies can be divided into three main categories: flea allergy, food allergy, bacterial and fungal infections, and environmental allergies (atopic dermatitis). Although flea allergy and environmental allergies are most common, often dogs can have multiple allergies so a thorough evaluation by your veterinarian or a veterinary dermatologist is recommended.
Flea Allergy Dermatitis
Flea allergy is caused by a hypersensitivity to flea bites. Dogs are exposed to flea saliva when bitten by fleas, and it doesn’t take many bites to cause an allergic reaction. Dogs with flea allergy typically develop itching over their backs, legs, bellies and tail. This condition is known as flea allergy dermatitis. The itching and allergic reaction can cause development of “hot spots” andsecondary bacterial infections.
Diagnosis is made based on the pattern of itching, which your veterinarian can help to identify. In many cases (but not all) there will be visual evidence of fleas such as flea “dirt” (flea feces appearing as black specks). However, visual evidence of fleas is not always present as fleas spend the majority of their lives “off” of the dog and fleas can be removed in the process of itching and grooming by the dog. Treatment includes preventing exposure to fleas in your pet’s environment in combination with strict flea prevention methods.
Fleas aren't the only critters that like to live on your dog. Mites can also be a pain, though they are a whole lot smaller. The two most common types of mites, sarcoptes and demodex, can cause secondary skin infections in addition to itching. And while sarcoptes mites tend to affect the ears, elbows, and chest of a dog, demodex mites are less particular and can appear anywhere on your dog's body.
Treatment for mites includes shampoos or special dips, topical preventatives, and intensive sanitation – meaning you’ll need to thoroughly clean your pet’s vacuuming and bedding. Your veterinarian will also likely prescribe something to control the itch and treat any secondary skin infections.
Bacterial and Fungal Infections
An itch has to be scratched, but all that increased scratching by your dog damages the skin, which can result in bacterial and fungal infections as secondary conditions to itching. Common signs of infection include inflamed, reddened skin, areas of hair loss, and ear infections. These infections also often cause your dog to smell badly. In order to diagnose a bacterial or fungal infection, your veterinarian will collect samples for culture or examine under a microscope.
Treatment for bacterial or fungal infections includes topical and/or oral medication to help heal your dog’s skin barrier and reduce itchiness.
Although food allergy is the least common allergy in dogs, it can mimic other allergies so it is important to eliminate it as a cause of itching in dogs with non-seasonal allergy symptoms. In some dogs it can also cause gastrointestinal symptoms (vomiting, diarrhea). As with other types of allergy, itching with ear and skin infections are common.
The only way for your veterinarian to diagnose food allergies is through a strict “hypoallergenic” dietary trial for 8-12 weeks. Protein sources are the most common food allergens. Therefore, novel protein diets are most often recommended as they contain unique protein sources (rabbit, venison, duck based diets) to which your pet has not been exposed to in the past. Prescription diets are preferred because these diets are highly purified and not contaminated with other protein sources (such as beef or chicken) which can occur under less strict manufacturing processes. Once food allergens are identified, control is through strict avoidance of these ingredients.
Environmental Allergies (Atopic Dermatitis)
Environmental allergies include both indoor allergens (house dust mites, molds) and outdoor allergens (pollen, weeds, grasses, trees). These are the same allergens that cause “hay fever” in people. When concentrations of these airborne allergens increase, it can trigger itching and secondary ear and skin infections in some dogs. This condition is known as atopic dermatitis. Certain breeds appear more likely to developing these types of allergies including many terrier breeds, Golden Retrievers, Labradors, and Shar Peis.
Symptoms can be seasonal or non-seasonal depending on what specific allergens are bothering your dog. Facial rubbing and foot licking are the most common types of itching seen; repeated ear and skin infection are common. Diagnosis is made based on the pattern of itching and eliminating all other causes of itching (bacteria and yeast infections, food allergy, flea allergy and other parasitic infections such as lice and mites).
Unfortunately, there is no cure for environmental allergies and therapy for this disease is life-long. However, symptoms are highly manageable. Milder cases are often controlled with antihistamines and topical therapy alone. In more severe cases, your veterinarian or veterinary dermatologist may recommend allergy testing (skin or blood testing) which can be used to identify specific allergens to which your pet is reacting. Allergy injections given over time can then help reduce your pet’s sensitivity to these allergens. Because this therapy can require 6-12 months for benefits it is often combined with other anti-itch therapies (drugs, topical shampoos, rinses and sprays) to help keep your pooch happy and comfortable.
If you have any questions or concerns, you should always visit or call your veterinarian – they are your best resource to ensure the health and well-being of your pets.