Spring is here! Have your allergies been driving you crazy? Every year, when the forsythia is in bloom, I get out the Benadryl and stock up on tissues. But, is this the right treatment for my dog? Pets, like people, may develop allergies. In the dog, the most common symptom associated with allergies is itchy skin, either localized to one area or encompassing the entire body. In some cases, symptoms involve the respiratory system. Affected animals may exhibit coughing or sneezing and have clear discharge from the eyes or nose. In other cases, the allergic symptoms affect the digestive system resulting in vomiting and diarrhea. Some of the most common allergen categories include fleas, food, and environmental.

Insect bite allergy is the exaggerated inflammatory response to the bite or sting of an insect. Arachnids, such as spiders and ticks, and insects including fleas, black flies, deer flies, horseflies, mosquitoes, ants, bees, hornets, and wasps can cause an allergic reaction. Flea saliva is by far the most common insect allergen in dogs and causes flea allergy dermatitis (FAD). Most dogs experience minor local irritation from fleabites. The FAD dog will react to a single bite with severe itching. A dog with FAD will bite and scratch itself and may remove large amounts of hair, especially in the tail-base region. A secondary bacterial infection may develop in the areas of broken skin. Even the bite from a single flea may result in a dog with FAD developing severe signs. Therefore, strict flea control is essential.

Food allergies develop in response to the consumption of a particular protein source. Dairy, beef, wheat gluten, chicken, eggs, lamb, and soy are commonly associated with food allergies in dogs. Food allergies may cause itching, digestive disorders, and respiratory signs. Food allergies typically do not respond well to corticosteroids or other medical treatments. The most accurate way of testing for food allergies is through an elimination diet or “food” trial. In a food trial, the dog is placed on a diet containing novel proteins (ones the pet has never been exposed to before and therefore not likely to be allergic to) or a hydrolyzed protein diet. In a hydrolyzed protein diet, the protein source is broken down into extremely small components effectively “hiding” it from the immune system. Dogs with food allergies will not react to hydrolyzed proteins. A dog is deemed to have an allergy to food if all or most clinical signs resolve after a 4-12 week trial of a strict hypoallergenic diet.

Atopic dermatitis, also known as allergic dermatitis or canine atopy, occurs when an animal develops a hypersensitivity reaction to common substances found in the environment. These may include pollens from trees, grasses or weeds, mold, mildew, and dust mites. Many of these allergens are found seasonally, such as ragweed, tree, and grass pollens. Therefore, dogs exhibit clinical signs only during certain times of the year (spring and fall). Other allergens such as mold, mildew, and house dust mites are present year-round. Affected dogs show signs regardless of the season. In most dogs, signs of atopy manifest as itchy skin (pruritus). Many dogs will rub their face, lick their feet and scratch their axillae (underarms). Treatments include steroids, shampoos, immune modulators and/or desensitization with allergy serums. New treatments including Apoquel and Cytopoint, show definite promise for improving the quality of life in dogs with chronic atopy.

Back to the question, “Can I give my dog Benadryl for allergies?” The answer is yes, with a few caveats. Benadryl may help improve signs of itch if the allergy is mild. However, Benadryl is an antihistamine and most dogs need more relief than a simple antihistamine can provide. Allergic dogs may also suffer from skin infections. Skin infections require antibiotics and specialized topical therapy to resolve. A skin infection will not improve if Benadryl is used as the sole treatment. The best course of action, if you feel your pet is suffering from allergies, is to schedule an appointment with your Longwood Veterinarian to discuss presumed triggers for the allergy and potential treatment options. Severe cases may be referred to a veterinary dermatologist for further testing and evaluation.


Studies in people have shown chronic itch to be as debilitating as chronic pain. Help is just a phone call away, please call your Longwood Veterinary Center veterinarian, serving the Greenville, Kennett, and Chadds Ford communities for the past 20 years!

Written by: Tara Corridori, LVT