What Causes Allergies in Dogs?

While humans show allergy symptoms often through their sinuses, allergies in dogs express themselves through the skin, resulting in overall itchiness and ear infections. Knowing the cause of the allergies can often help treat them, causing your dog greater comfort.

Flea Allergies

Even after you've eradicated a flea problem in your house, your dog could show signs of a flea infection if he's allergic to fleas. Bites can itch up to three weeks later for flea-allergic dogs, so it's important to prevent flea bites altogether.

If your dog is allergic to fleas, you will often notice him biting the lower half of his body, such as his sides, stomach, rear legs and possibly near his tail.

There is no way to treat these allergies, but they can be easily prevented by giving your dog flea preventative every three to four weeks. Try not to miss a dosage because even one rogue bite can cause the allergies to continue for another few weeks.

Food Allergies

Many dogs who eat the same food for long periods of time develop food allergies to those familiar substances. Dogs are commonly allergic to corn and wheat, which are found in many cheap dog foods, but they can be allergic to a range of things, including protein sources, fruits and vegetables or preservatives and other filler found in dog food.

Allergy tests are infective for diagnosing food allergies, so veterinarians usually prescribe a food trial, during which your dog is removed from all food and treats except a food with one novel protein source, such as duck or rabbit, and one carbohydrate source, such as potato. Then, foods are slowly added back in to determine which trigger allergic reactions.

If your dog has a food allergy, it should clear up when placed on the novel protein. If you don't want to go through a full food trial, try switching to a different brand of food with a different protein source than you currently feed and see if there are improvements.

Environmental Allergies

If your dog has environmental allergies, the symptoms will often appear seasonally. Environmental allergies are usually diagnosed by elimination. Once flea and food allergies are under control, environmental allergies are all that remain.

It's very difficult to treat environmental allergies since you can't control your dog's exposure to the environment. Some dogs respond well to antihistamines or steroids that treat the symptoms.

Dermatologists are now giving dogs allergy tests during which the dog's skin is exposed at low levels to likely allergens. Those that cause a reaction are used to create a vaccination through which the dog is exposed at low levels to the allergens for long periods of time, allowing him to build up an immunity.

There are three main types of dog allergies: fleas, food and environmental. The difficulty in diagnosis is that your dog may have only one or all three. If your dog is troubled by persistent allergies, visit a certified canine dermatologist for a definitive diagnosis and begin to ease your dog's symptoms.