Our Pets and Allergies: Knowing the Difference Between Environmental and Food Allergies

Categories: Pet Care & Training
Always be aware of excessive grooming, biting or scratching – all of these could be an indication of an allergy.

Have you ever wondered if your pet might be experiencing an allergic reaction? When we think of allergies, we generally think of the sneezing, runny eyes, and hay fever. But in cats and dogs, allergies tend to look a little different.

When allergies present themselves in our pets, they do not usually cause respiratory signs.  The majority of allergies in our pets result in skin diseases, often characterized by itching, red skin, and hair loss.  Sometimes we also see gastrointestinal effects such as diarrhea, particularly with food-related allergies.  Allergies can be a frustrating condition in our pets because they can sometimes be difficult to control and treat.

Itching may be an indication of either a food allergy or an environmental allergy.

Food Allergies V.S. Environmental Allergies

In both cats and dogs, allergies can be classified into two major types: food and environmental.

Food allergies account for about 10% of skin allergies in pets. The allergen in these cases is usually to a protein in the food, such as chicken or beef, but can also be to a carbohydrate, preservative, or food dye. These allergies are generally treated by feeding the pet a limited ingredient diet that contains a novel protein that the animal has never eaten before, such as rabbit or venison, and usually one other carbohydrate source, such as green pea. It can take up to six weeks to see any resolution of the skin disease after changing the diet in this way. Our pets can also have both food and environmental allergies, so a diet change might be necessary, but not the only treatment needed to solve the problem.

Environmental allergies include allergic reactions to parasites, commonly called Flea Allergy Dermatitis (FAD). FAD causes hair loss and itching, usually starting just above the base of the tail and spreading outwards from there. In cats, FAD also causes a rash called miliary dermatitis, which can be identified by feeling for tiny scabs all over your cat’s skin. FAD is an allergic reaction to the flea’s saliva, and in a susceptible animal, it only takes one flea to cause a reaction. The only way to control FAD is to prevent fleas by using a high-quality flea control product recommended by your veterinarian.

What your pet is eating may be the cause of an allergy – this can be determined by trying out a limited ingredient diet.

Other environmental allergens can be the same things that trigger hay fever in us – things like pollen, molds, dust mites, and so on. In a dog or cat that has an allergy to these types of substances, we call it atopy, which is an exaggerated response by the immune system to something in the environment that shouldn’t cause an immune response. In dogs, we see chronic ear infections, and the face, feet, armpits, and lower belly tend to be very itchy, causing dogs to scratch and lick these areas. Cats will also be very itchy and may develop ear infections, sometimes even pull out their fur. Cats also have a condition called eosinophilic granuloma complex, which can cause ulcers on the lips, (sometimes known as “rodent ulcers”) mouth, and raised, red plaques on other parts of the body.  In both pets, the trauma to the skin causes secondary infections with bacteria and yeast that further the disease progression. Treating these allergies requires clearing any ear and skin infections present, as well as addressing the allergy itself.

Dr. Ann Marie McNamara, Veterinarian at Lollypop Farm.

Allergy Testing for our Pets

When it comes to determine what type of environmental allergies your pet may have, veterinarians use either intradermal skin testing or serologic testing. Intradermal testing involves injecting a small amount of a pure allergen under the skin and measuring the allergic response; a panel of allergens is tested and this process requires sedation. This type of testing is usually only performed by boarded veterinary dermatologists. Serologic testing, on the other hand, uses a blood sample to test an animal’s response to allergens. Serologic testing is less invasive and your general practice veterinarian can take the sample and send it to the lab. However, the results are often not as clear cut to interpret as intradermal testing.

Dealing with our Pet’s Allergies

In our pets, we treat allergic skin disease in a number of ways. Antibiotics, antifungals, and ear medications are used to control secondary infections, including both oral and topical medications (such as medicated wipes or shampoos). In the cases of food allergies and FAD, we can prevent exposure to the allergen by a diet change and using high quality flea control. The allergic response itself can be dampened with antihistamines, steroids, or other immune-modulating drugs, such as cyclosporine or Apoquel. There are newer treatments that target the specific players in the immune response that are responding abnormally in atopy.  Finally, there are allergy shots like we used in people, that use the data from the intradermal or serotologic testing to create a custom blend that helps desensitize the immune system to those allergens.

If your pet is always scratching, and his or her skin is red and smelly and there is hair loss, see your veterinarian. Allergies are one cause of skin disease in your pet, and your veterinarian will be able to determine if the skin disease is atopy, FAD, or some other disease and help your pet feel better.

This guest blog was written by Dr. Ann Marie McNamara, Veterinarian at Lollypop Farm

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