Itching? Scratching? Ear Problems? The ABCs of Canine Allergies

Canine allergies can be a real problem for many dogs. photo: AdobeStock

Skin and ear problems are common in dogs, and they’re one of the most frequent reasons owners bring their pets to the veterinarian. While there are many different things that might cause a pet to lick, rub, scratch, or chew themselves, the most common one is allergies. 

An allergy is defined as a chronic condition involving an abnormal reaction to an ordinarily harmless substance called an allergen. Allergens can trigger a response that starts in the immune system and results in an allergic reaction. 

When dogs are allergic, instead of the sneezing or congestion that humans experience, they generally show their allergies in the skin and ears.

In order to better understand what your dog may be suffering from, it helps to break down some allergy basics.

Three Main Types of Canine Allergies

Environmental Allergies. Just like people, dogs may be allergic to pollen, dust, or molds. Allergic dogs may scratch all over, especially at their armpits, belly, ears, and paws. They may also have recurrent skin and ear infections or lick their paws. Take note if you see these reactions during a particular season, like spring or fall. This may help determine the likely allergen.

Food Allergies. Animals with food allergies may exhibit very similar signs as pets with environmental allergies, but the itching is not seasonal. Animals may develop a food allergy at any time in their life, even if they have been eating the same food all along. In fact, one of the most common canine food allergens is chicken. Besides itchiness, food-allergic dogs may also experience ear or skin infections. The symptoms of a food allergy usually do not improve much with anti-itch medications. 

Parasite Allergies. Fleas can cause itching and hair loss in dogs due to the simple irritation of their bites, secondary bacterial infections, or to a flea bite allergy. Animals with flea bite allergies will often scratch and lose hair on their backs near the tail. In flea-allergic animals, even one flea bite can cause a reaction. Mange mites (sarcoptes or scabies mites) can also cause intense allergic reactions and extreme itchiness. Scabies may cause hair loss and crusts forming on the dog’s ears and elbows. Scabies mites can be very difficult to find and, if suspected, should be treated even if skin samples don’t reveal mites. 

How To Identify Allergies

Some parasites, like fleas and ticks, are usually easy to find since they are visible to the naked eye, but other skin parasites may be tricky to find. Demodex mites live inside hair follicles and can usually be found by veterinarians with skin scrapings. Skin scraping involves using a dull blade or medical skin spatula to scratch the skin to acquire samples of skin cells and any parasites that may be present. Scabies (sarcoptes) mites can be very hard to find and may be present even if skin scrapings are negative. There are several other types of parasites, like Cheyletiella (also called walking dandruff) and a variety of species of lice, which you’ll also need help from your vet to detect. Luckily, there are newer prescription medications to treat them all!

Unfortunately, no easy test exists that will give you all the answers about your dog’s allergies. Blood or skin testing for food allergies is not usually accurate in dogs and cats.  Since you can’t rely on food allergy testing, the only way to determine if your dog has food allergies is to talk to your vet about performing a diagnostic diet trial for 8-12 weeks. Prescription hydrolyzed protein diets are the most reliable diets since the proteins in them have been broken down into small pieces that the immune system can’t recognize. They have also been tested for impurities. During the test diet, all other food, including treats, supplements and chews, must be stopped.

Once food allergies and parasites have been eliminated, accurate testing does exist for environmental allergens. Blood allergy testing is more convenient and can be performed by most veterinarians but may be less accurate than skin testing. Skin allergy testing tests the actual organ that is involved in the allergy (the skin), so is more accurate than blood testing, and is typically performed by veterinary dermatologists. Once the allergy test results are known, allergic pets can receive allergy shots (just like people!) to desensitize them. 

Other Causes of Irritation

Although the main reason for a pet’s itchy skin may be allergies or parasites, they can also develop secondary bacterial or yeast infections, which can keep the itchiness going even after the underlying cause is treated. These infections may cause red, crusty, flaky skin as well as hair loss, pimples, and red bumps. If an irritation persists, consult your family vet or seek the help of a board-certified veterinary dermatologist.

While we never recommend self-diagnosing your best dog friend, we hope this information helps you better understand how you can speak up for your pup and spare them from chronic itching and scratching.