Pet Allergies

April 08, 2024

Allergies are a common problem affecting our cat and dog companions. The two main types of allergies we encounter, and that will be discussed here are food allergies and environmental allergies. It can often be difficult to differentiate between the two.

What are allergies?

Allergies are an exaggerated immune response to food or environmental triggers, meaning the body produces antibodies against substances (allergens) that other animals can tolerate just fine. These antibodies recognize the allergens as harmful and an immune response is created to try and protect the body from the substance, this creates signs such as redness, itching, inflammation, and others in our pets.

Clinical Signs

Signs you may notice in an allergic pet are itchiness- manifested as frequent scratching, biting or licking, hair loss, face rubbing, ear infections, eye discharge, or flaky skin. The most commonly affected areas on the body are the face, paws, limbs, ears, and abdomen. Both food and environmental allergies have this distribution, animals with environmental allergies are nearly always itchy, whereas they may or may not be itchy with food allergies.

Food Allergies

There is a difference between true food allergy and food intolerance. Skin signs manifest only with a true food allergy. The origin of food allergies in animals is not well understood, but is different compared to humans, which is why we cannot reliably test for food allergies in our pets. The most common food allergies are to protein sources, with beef and chicken being the top allergens in dogs. Dairy, eggs, and wheat are also potential causes, but to a lesser extent. The most common food allergies in cats are beef, dairy, lamb and fish. Food allergies can present at any age, but if an animal presents with itching less than one year of age, food allergies are a top suspicion. Cats may present at any age with non seasonal itching, 4-5 years old is the most common age of presentation. Many people are interested in allergy testing to try and definitively identify the specific foods their pet is allergic to, unfortunately there are no reliable food allergy tests for our pets, there is no proven correlation between the findings on the tests and the true disease. Because of this, elimination diet trials are our only means of diagnosis (and treatment). We generally recommend prescription allergy diets, as over the counter diets (from the pet store) may contain proteins not listed on the ingredient list, such as through cross contamination. We pick novel proteins or hydrolyzed protein diets for our trials. Novel protein is a protein the animal has never had before, such as rabbit, pork, or kangaroo. Hydrolyzed protein diets are protein sources the animal likely has had before (chicken for example), but the protein has been hydrolyzed, or broken up so finely the body is unlikely to recognize it as an allergen.

Environmental Allergies

Environmental allergens for dogs include pollen, molds, grasses, trees, and dust mites. Diagnosis of environmental allergies is done by excluding all other causes of itch. Environmental allergies usually present between 1-3 years of age. They may have a seasonal distribution, meaning signs are worse in the summer, and resolve in the winter, or vice versa. But, depending on the allergen, signs may persist all year. Allergy testing: Because of the type of immune response that is mounted in environmental allergies, we can reliably test for them in our pets as we can in humans. This is not a diagnostic tool, but rather to help us identify allergens if we are considering the use of immunotherapy. There is serum testing (blood test) as well as intradermal testing. Intradermal testing is where a small amount of allergen is injected under the skin to assess the response, this is performed with a dermatologist, while blood testing can be done in our clinic. Neither test is perfect, and false results can occur.

How to diagnose and treat

Before diagnosing and treating allergies, we must always search for other possible causes of the signs, such as flea’s, mites, ringworm, or secondary infections such as yeast or bacteria. Secondary infections occur when an animal has been traumatizing the skin due to itch, and this in turn makes the animal even itchier! We often do this by obtaining samples of the skin (swab, tape, scrape) and looking at them under the microscope. If no other causes for the clinical signs can be identified, then we can move to allergy treatments. Thankfully there are many treatment options available to help manage your pets signs:

• Medicated, calming or moisturizing shampoos can be utilized depending on the location and type of signs your animal has. Bathing helps to remove environmental allergens from the skin, but also treat secondary infections and help replenish a compromised skin barrier.
• Apoquel and Cytopoint: these are medications that block the transmission of itch cytokines, which are produced in large amounts when the body is reacting to an allergen. They have minimal side effects and are very effective for keeping your pet comfortable. Apoquel is a daily pill, while Cytopoint is an injection given every 4-8 weeks
• Steroids: Steroids are very effective at reducing inflammation in the body, they can reduce redness, swelling and itch in our patients, but unfortunately are not as targeted as the medications discussed above and have a host of side effects, we try and use steroids in short courses, or at the lowest effect doses.
• Immunotherapy: With environmental allergy testing we can identify an animal's specific allergens and create injectable or sublingual (oral) vaccines to modify the body's immune response. It can take many months for clinical improvement, and success is between 50-80%
• Diet trials: As discussed above, novel or hydrolyzed protein diets are the treatment choice for suspected food allergies. The diet must be fed strictly for a total of 8 weeks to assess an animal's response. Allergies can be very challenging to manage and require lifelong care, but it is very rewarding to treat these patients and bring relief to the animals (and their owners). Let us know if we can help you manage your pets allergies!

Dr. Alyssa Vickers