Dogs and Allergies: Symptoms and Testing

When dealing with dogs and allergies you have to remember that dogs don’t react to allergens like humans do. Canine allergy symptoms usually present as skin conditions. Even inhalant allergies, such as pollen, produce skin reactions and hot spots. Allergy testing, while capable of identifying common canine allergies, cannot identify every possible allergen, so some detective work is required of both the dog’s owner and his veterinarian when a dog has allergies.

Atopic Dermatitis

Atopic dermatitis is a contact allergy, meaning something in the dog’s environment is causing the allergic reaction. Dust, mold, pollens and flea saliva can all cause atopic dermatitis.

Atopic dermatitis usually develops within two years of birth. Allergy symptoms caused by atopic dermatitis include:

• chewing abdomen or hindquarters
• chewing footpads
• excessive grooming
• hot spots
• licking
• red, inflamed ears, often hot to the touch.

A dog with allergies may lick excessively between his toes, under his armpits and in the groin area. This licking results in saliva stains, a browning of the fur.

Food allergies, flea infestations and scabies mites can all mimic atopic dermatitis. These conditions must be ruled out before treating dogs for contact allergies.

Hot Spots, Dogs and Allergies

Hot spots are bacterial infections that can plague a dog’s skin. Hot spots are often triggered by allergies, which provide bacteria with the environment they need to flourish.

Food Allergies

• Twenty percent of dogs in the U.S. suffer from allergy symptoms. Of this number, ten to fifteen percent have food allergies or food sensitivities. Common allergy symptoms associated with dogs and food allergies include:
• rectal itching
• ear inflammation
• hair loss
• head shaking
• itchy skin
• licking or chewing of the front paws
• loss of appetite.

The similarity between food allergy symptoms and symptoms of atopic dermatitis is readily apparent, making allergy testing difficult. In rare cases, food allergies produce additional symptoms, such as:

• asthma-like symptoms
• behavioral changes
• diarrhea
• flatulence
• seizures
• sneezing
• vomiting

Dogs are rarely allergic to a specific dog food. Instead, allergy symptoms usually develop from an ingredient in the dog food. Possible food allergens include beef, chicken, fish, lamb, pork, eggs, milk, soy, corn and preservatives.

Respiratory Allergies and Symptoms

The symptoms of an inhalant allergy are similar to other canine allergy symptoms, with itching often worse in the feet, armpits, groin and flanks.

Common inhalant allergens include pollens, molds, dust mites and chemicals. The inflammation caused by inhalant allergies is often responsible for ear infections in dogs.

Allergy Testing and Blood Tests

Canine allergies, like human allergies, can be difficult to identify. First, conditions that mimic allergies must be ruled out. As dogs can suffer from many different skin conditions, this alone presents a challenge. A blood test may detect histamines, indicating the dog is reacting to an allergen.

Allergy testing can identify the most common canine allergies. During allergy testing, a portion of the dog’s coat is shaved off, and tiny amounts of numerous allergens are scrapped into the dog’s skin. If the dog is allergic to a specific substance the skin will develop an allergic reaction in that area.

While allergy testing cannot test for every conceivable allergen, it can test for some of the most common allergens: dust mites, flea saliva, pollens and molds.

Identifying food allergies through allergy testing is not possible. Instead, the dog is put on an elimination diet. During the elimination diet the dog is fed a homemade mix of two parts starch (potatoes or rice) and one part protein (duck, lamb or venison). The exact ingredients don’t matter as long as the dog has never eaten them before.

While on the elimination diet, dog owners slowly add possible food allergens back into the dog’s diet, watching carefully for any allergy symptoms.

Treating Dogs for Allergies

The best treatment for dogs with allergies is one of avoidance: food allergy symptoms can be prevented simply by not feeding the dog the allergen. In other cases, however, avoidance may not be possible.

Dogs who are allergic to flea saliva should receive a flea preventive. For other allergies, treatment may focus on relieving symptoms.

Short-term relief from itching and inflammation can be treated with cortisone, but only if scabies has been ruled out as the source of apparent allergy symptoms. Antihistamines may be administered under a veterinarian’s advice (never attempt to dose your dog without first consulting your vet). Cool baths with Epsom salts or medicated shampoos can also provide an itchy dog with some relief.

Ear Infections, Dogs and Allergies

Ear infections often result from canine allergies. Allergy symptoms include inflammation, which narrows the ear canal and promotes bacterial growth. Accidental invasion of the ear canal by pollen, mold or other allergens often precedes an ear infection.