Dogs are most commonly allergic to flea bites, and they can be allergic to certain foods, but environmental allergies often present the biggest challenge to caring owners who want to help their dogs.
Preventing exposure to allergens is the simplest solution to a hypersensitive overreaction to a substance. But exposure to fleas can be controlled with flea-preventative medicines or pesticides, and exposure to allergy-causing foods can be curtailed as soon as an observant owner can identify which foods trigger the dog’s hypersensitive response. It’s much more difficult to prevent your dog’s exposure to pollen, fungal spores, and/or dust mites – invisible stuff in the air.
Extreme itching is the classic sign of an allergic reaction in dogs, known more technically as a hypersensitive immune reaction. In a true allergic response, the dog’s immune system detects an ordinarily benign substance and treats it as a pathogenic invader. In the simplest terms, the allergic dog’s body produces chemical defenses to the erroneously identified “invaders,” prompting an acute inflammatory response. This, in turn, causes the dog to itch all over.
Flea-bite hypersensitivity can generally be ruled out if you’ve never seen a flea on your dog or your other pets and you practice good flea prevention. Food allergies affect dogs year-round, so if your dog doesn’t have fleas, and his allergy symptoms wax and wane with the seasons, they are probably environmental.
Understanding Environmental and Seasonal Allergies in Dogs
Canine Atopic Disease (CAD), the veterinary term for environmental allergies, affects an estimated 15 percent of all dogs. Dogs with CAD itch and scratch. Any dog can have an occasional itch, but dogs with CAD will stop in the middle of eating or playing in order to scratch or chew their feet, rub their faces against carpets or furniture, lick their stomachs and groin areas, or scratch their “armpits.” The trigger may be pollen, mold spores, dust mite droppings, or other environmental antigens.
Constant licking can create new problems by damaging the skin and producing lick granulomas – thick, hairless red patches that may be accompanied by infection. Violent head shaking (a reaction to an itching sensation in the ear) can result in an aural hematoma, in which a blood vessel in the ear pinna (the ear “flap”) bursts, causing painful and disfiguring swelling.
Another allergy-related symptom is the hot spot, an outbreak of pyotraumatic dermatitis, wet eczema, or a Staphylococcus intermedius infection. Painful, swollen, and warm to the touch, hot spots can emit pus and smell awful. In many dogs, hot spots mark the return of seasonal allergies.
Identifying Your Allergic Dog’s Allergens
Environmental allergies have many possible causes and triggers, so veterinarians spend time looking for and ruling out potential causes. You can help by being observant and keeping track of your dog’s medical history. Even a simple note on a calendar (“March 12: Leroy licking his feet”) can help lead to a diagnosis. Note any changes in your dog’s health, habits, or attitude, and keep your notes from year to year.
“You can find almost everything you need to know by taking a good history,” says Donna Spector, DVM, DACVIM, an internal medicine specialist who has practiced at leading institutions including the Animal Medical Center in New York. “There are good clues to be found in such facts as the environment the dog lives in, when the allergies started, the location on the body that is most affected, whether there is a seasonal component, the dog’s breed, and any medications he’s been given and what sort of response he had to those.”
Intradermal allergy testing, which is considered the gold standard for the diagnosis of atopic dermatitis, involves injecting small quantities of 40 to 60 different allergens into the dog’s skin, typically under general anesthesia. A visible swelling will occur at the injection site if a dog has a reaction to the allergen.
Another testing method involves checking a blood sample for antibodies to allergens that are known to contribute to atopic dermatitis. The results of these tests can be used to formulate an allergen-specific immunotherapy based on the offending allergens. Note that blood tests for canine atopic disease are not reliable for diagnosing food allergies, although they are sometimes used for that purpose.
Preventing or Minimizing Exposure of Allergens
Your veterinarian will be an invaluable ally in helping you identify the cause of your dog’s allergy symptoms and recommend medications for relieving those symptoms (and treating any secondary infections caused by excessive licking or scratching). Also, she may recommend allergen immunotherapy, also known as desensitization. This involves gradually increasing exposure to relevant allergens through subcutaneous injections or drops given under the tongue, in order to help build tolerance to allergens. Immunotherapy may take up to a year to become effective but, when successful, its results are long-lasting.
Veterinary care aside, there are a number of things that you can do to significantly reduce your dog’s exposure to the environmental allergens that wreak havoc on her body.
Prevention is crucial in dealing with environmental allergies, so consider when, where, and how your dog might be exposed to substances that trigger reactions.
Indoors, forced-air heating and air conditioning can spread allergens such as dust (and dust mites) and pollen, so install filters that reduce their migration. Whenever possible (such as when vacuuming, or in your heating system) choose HEPA (high efficiency particulate-absorbing) filters to avoid reintroducing allergens back into the pet’s environment.
Reduce indoor exposure to dust and dust mites with frequent vacuuming (with your dog in a separate room) and dust frequently. Consider removing dust reservoirs such as house plants, rugs, carpets, fuzzy throws, fuzzy toys, and pet beds. When it isn’t possible to remove or replace these items, do what you can to keep them allergen-free, by washing them frequently (and drying in the dryer, not on a line outdoors).
Mold spores are another common allergen for hypersensitive dogs. Mold is often overlooked as an environmental allergen,but its multicellular fungi are present almost everywhere. Favored mold surfaces include wood, leaves and plants, air ducts, soil, and basements.
Mold thrives in damp, humid environments, multiplying through microscopic spores that disseminate through the air. Dehumidifiers and improved air flow through your house can help discourage mold growth. Whenever possible, keep your dog and his bed out of damp basements or garages. Professional mold remediation may improve your dog’s health, and yours, too!
Spring and Summer Are Most Challenging for Seasonal Allergies in Dogs
These seasons are when pollen-related allergies spike. It only makes sense to limit your dog’s outdoor time during peak allergy seasons – don’t let your dog put her head out the car window while traveling, and don’t let her nap on a pollen-covered deck or porch. If you want to give her an opportunity to soak up some sunshine, spray the deck off first or put down a clean blanket for her to lie on.
Keep lawn grass cut short to reduce seed and pollen production, and keep your dog off the lawn for one to two hours after mowing or when the lawn is wet.
You’ll probably be able to develop a sense for which type of pollen most aggravates your dog’s allergies. Is it the early-blossoming trees and plants? Grasses? During times of peak pollen levels of the offending plants, bathe your dog frequently using hypoallergenic shampoos, leave-in conditioners, cool water rinses, and soothing coat sprays. Rinse your dog’s paws when coming in from outdoors, and wipe her coat several times daily with a damp microfiber cloth to help remove pollen. And prevent her from licking her paws or coat (thus ingesting pollen) as much as possible.