The allergy facts are in: Allergies may affect up to half of all American dogs, and there are three major allergens that cause most of the trouble. Fleas, inhaled substances like pollen or dust, and food are the main culprits in most canine allergies. Let's look at each in a little more detail, because the symptoms they cause in your pet may look extremely similar.
What an Allergy Is
An allergy is an overreaction of a sensitive animal's immune system to something it perceives as a threat. This substance is called an allergen, and it causes the immune system to release a chemical called histamine to fight the invader. Histamine causes skin redness, irritation and the formation of hives, along with digestive system problems, including diarrhea and vomiting.
Although your dog's allergy may seem to appear suddenly, it's actually a problem that may have been building for years. Consistent exposure to an allergen over time that reaches a point of overexposure is what commonly causes an allergic reaction, so the food or pollen that didn't affect your dog last month or last summer may now cause problems for him.
Medications and environmental changes can help treat flea and atopic allergies, while a dietary change is often required to resolve a food allergy problem.
Flea Allergies
Estimates indicate that 40 percent of all dogs are affected by flea allergies. Components of the flea's saliva cause an allergic reaction in sensitive dogs, and 15 different components have been identified as allergens. A single flea bite can set off an allergic reaction, and symptoms can last up to two weeks from that single bite.
Symptoms of flea allergies are mostly seen on the dog's skin, although the actual fleas themselves are often missing due to the dog's enthusiastic scratching and licking to remove the source of his itching. Other indicators of a flea allergy can include chewing at the base of the tail or hair loss, along with the presence of flea dirt (dark specks on the dog's skin) that fleas leave behind when they eliminate.
Atopic Allergies
The second most-common canine allergy is atopy, which affects about 15 percent of dogs. In atopic allergies, an inhaled allergen (e.g., dust, mold, pollen) causes an allergic reaction on your dog's skin. Symptoms include itching, skin irritation, recurrent ear infections that are difficult to cure, skin chewing and bald spots.
There seems to be a genetic component to atopic allergies, with some breeds being more prone to them. Susceptible breeds include:
- Bbeagles
- Belgian tervurens
- Boston, Cairn, Scottish, West Highland white and wire haired fox terriers
- Boxers
- Bulldogs
- Chihuahuas
- Dalmatians
- English and Irish setters
- Golden and Labrador retrievers
- Lhasa apsos
- Miniature schnauzers
- Poodles
- Pugs
- Shih tzus
- Shar-peis
Food Allergies
Canine food allergies affect about 10 percent of all dogs, and they are caused by either a protein or carbohydrate source in your dog's diet that his body suddenly sees as a threat. Problematic ingredients include cereal grains, dairy products, fish and meat. Symptoms most often show themselves on the dog's skin, and they can include face rubbing, head shaking, itching, sneezing and wheezing.