Dogs exhibit allergy symptoms such as itchy, dry skin and gastrointestinal signs including chronic vomiting and diarrhea, and it can be difficult to distinguish the cause among the three most common allergies in pets: flea allergy dermatitis, environmental allergy and food allergy, writes veterinarian Chase Constant. Gastrointestinal symptoms usually accompany food allergies, which also occur year-round, Dr. Constant points out. He adds that a food trial directed by a veterinarian is the best way to diagnose a food allergy.

Unlike humans, dogs cannot scratch their paws and are forced to lick and bite them when they are itchy. There are two things to consider when caring for an itchy dog: Treat the underlying cause of the itch, and treat any secondary infections that have developed.

Like people, dogs can have allergies, causing them to become itchy. We usually think of three types of allergies: flea allergy dermatitis (FAD), food allergy or environmental allergy. Some dogs are allergic to flea saliva, and it takes only one bite to set off them off and keep them itching for up to two weeks. The key to treating this allergy is avoiding contact with fleas, which is why most veterinarians recommend the use of regular monthly flea control.

Food allergies are very common in dogs and can cause mild to severe itching (paws, face, and ears), red skin, or even gastrointestinal signs (chronic loose stool or vomiting). Environmental allergies cause similar signs, excluding the gastrointestinal ones. One key to helping differentiate between these two types of allergies is timeline. Food allergies will continue year round, whereas most environmental allergies improve or resolve at some point during the year (in other words, they are seasonal, with the winter months usually being the better months).

Many times, a secondary infection (bacterial or yeast) has developed because the biting and licking has damaged the skin. If your dog is constantly licking or biting his paws, he should be evaluated by your veterinarian, because it can be a painful condition and these infections need to be treated with oral or injectable medications (antibiotics or antifungals), with medicated shampoos or with both. Then the underlying allergy needs to be addressed.

A food trial is needed to determine a food allergy. This involves feeding your dog a very strict diet over several months with a protein source he has never been exposed to, like rabbit or venison. Your vet can help you plan a proper food trial to determine if your dog has a food allergy, then what food should be fed on a long-term basis.

Environmental allergies can be treated with different medications. Some dogs with mild allergies or allergies that last only a few weeks or months each year can be treated with antihistamines like Benadryl. Some dogs require more aggressive medications that actually suppress the immune system. Skin testing or blood testing is available and can determine what things in the environment are causing the allergies. This information is used to formulate allergy shots, which sensitize your dog to the allergens. This process can take several months to a year to start working and will require lifelong use. This is a special procedure that not all veterinarians perform, and it may require seeing a board certified veterinary dermatologist or a veterinarian with a special interest in dermatology.

Remember: When you are sneezing constantly and rubbing your itchy, watery eyes, your dog may be going through the same thing and may need treatment.

— Chase Constant, VMD

One response to “Distinguishing the cause of allergic symptoms in dogs”

  1. Mary says:

    Thank you for the straight forward, helpful information. My dog says Thank you too!

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