 Like people, dogs can suffer from allergies.
As in the human population, the incidence of allergies in pets seems to be increasing.
While allergic humans may often sneeze, wheeze or even have serious respiratory
difficulties, allergic reactions in pets are mostly characterized by skin problems,
exacerbated by their primary symptom – itching and scratching. Dog allergies fall
into three main categories: flea allergic dermatitis, atopy, and food allergy. Many
pets can be affected by one or more allergy.
Food Allergy
What is food allergy and what are its symptoms?
Food allergy is an allergic reaction to one or more ingredients in a pet’s food.
The most common allergens are beef and milk products, cereals (wheat, corn, soya),
chicken and eggs. The exact cause of a food allergy is not known. Perhaps a change
in the pet’s immune system causes certain ingredients to be perceived as “foreign”,
initiating inflammatory mechanisms to fight off the perceived “intruder”.
The most common symptoms of a food allergy are itching, licking or chewing. Otitis
Externa (ear infection) along with other skin problems are also common in conjunction
with food hypersensitivity. Some pets may also have diarrhea and other digestive
problems. Symptoms can appear at any age, whether a pet has just started a new diet
or has been eating the same food for several years.
 How is food allergy diagnosed?
The only effective way for your veterinarian to diagnose a food allergy is to put
your pet on a “hypoallergenic” or “exclusion” diet for a minimum of 8-12 weeks.
Such a diet contains ingredients to which the animal has not been exposed in the
past. Because the source of protein causes most allergic reactions, exclusion diets
use proteins – often venison, fish or duck – that are normally not found in regular
pet food. An exclusion diet may comprise home prepared food or prescription commercial
hypoallergenic products.
If your pet has a food allergy, there should be a significant reduction in the symptoms
after the recommended period on the exclusion diet. To identify all the food allergens,
your veterinarian will recommend adding a single protein back into the diet every
1-2 weeks, while watching for a recurrence, or worsening, of symptoms. If this happens,
the veterinarian will recommend removing the offending ingredient from the diet.
How is food allergy treated?
The best way to treat your pet’s food allergy is to carefully monitor his or her
diet, in order to avoid flare-ups.
In rare cases, your veterinarian may also prescribe antihistamines and corticosteroids.
Flea Allergy Dermatitis
What is flea allergy dermatitis and what are its symptoms?
Flea allergy dermatitis (FAD), often called “flea bite hypersensitivity”, is a skin
disease caused by an allergic reaction to flea saliva. A
single flea bite can trigger the disease’s intense itching. Dogs with FAD chew and
bite their backs, legs, bellies or tails. This often leads to “hot spots”, or localized
hair loss and skin infections. You may find fleas and flea dirt (the flea feces
look like black specks) on your pet, although many dogs with FAD have very few fleas,
since they are constantly licking and chewing.
How is flea allergy dermatitis diagnosed?
Your veterinarian looks for the usual signs (scratching, skin sores, the presence
of fleas and/or flea dirt). He or she may also perform a skin test to confirm that
fleas are causing the problem, as FAD symptoms can resemble those of other conditions,
including external parasites (mites, lice), infections and other allergies, that
cause severe itching.
How is flea allergy dermatitis treated?
The best way to treat FAD is to prevent fleas from attacking your pet. Various insecticides
and insect growth regulators that eliminate flea infestations are available. Your
veterinarian can recommend the right product for your pet. Daily vacuuming and frequent
washing of your pet’s bedding can also reduce your home’s flea population.
To break the “itch-scratch” cycle that leads to skin infections, your veterinarian
may prescribe corticosteroids, antihistamines and essential fatty acids to relieve
irritation. Warm water baths and anti-itching shampoos and conditioners also help.
What is most important to realize is that there is no cure for FAD: your pet will
always be allergic to flea bites and you must be continually on your guard to prevent
further problems. Flea prevention is a must.
Atopy
What is atopy and what are its symptoms?
Atopy, or environmental allergy, is an allergic reaction to airborne substances
like pollen, molds, house dust mites and animal dander (skin or hair fragments).
It is most common in dogs, but some cats are also affected. The incidence of atopy
depends as much upon a pet’s genetic susceptibility as exposure to the allergen
itself. (An allergen is any agent causing the allergic reaction.) Terriers, Setters,
Retrievers, Dalmatians, and Chinese Shar-Peis are particularly prone to atopy.
Itching, mostly around the face, feet, lower chest and belly, is the primary symptom.
Depending on the cause, this may occur only seasonally (pollen) or year-round (molds,
dust mites and dander). “Hot spots”, other skin infections and ear problems can
develop. Frequent scratching due to chronic irritation may lead to hair loss. These
signs can be seen from 4 months to 7 years of age but are typically first noticed
around 1-3 years of age.
How is atopy diagnosed?
Atopy is confirmed through a process of elimination. Other causes of itching, such
as fleas, mites, lice, bacterial and yeast infections, as well as food allergies,
must be ruled out first. Your veterinarian will ask you for a detailed history of
your pet’s itching problem. Skin or serum (blood) testing for different allergens
may then be performed to help pinpoint the exact cause.
How is atopy treated?
Atopy is a lifelong condition and there is no known cure. However, there are a number
of ways to manage the problem:
- Anti-itch therapy, including the use of drugs, medicated shampoos and conditioners.
- Removing the source of the allergy from the environment as much as possible.
- Immunotherapy uses a series of injections to gradually accustom your pet’s system
to the allergen(s) causing the problem. Although its effectiveness varies, it provides
at least some relief for around 75% of pets with atopy.
- If the atopy is relatively mild (for example, occasional itching during the pollen
season), you can use “Elizabethan collars", T-shirts and socks to reduce irritation
by physically preventing your pet from scratching or biting themselves.
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