Dogs with Atopic Dermatitis: Causes, Diagnosis, and Treatment
Atopic dermatitis is a disease in which there is an inherited tendency to
develop IgE antibodies in response to exposure to allergens that areinhaled or
absorbed through the skin. This extremely common allergic skin disease is
second only to flea
allergy dermatitis in frequency, and affects about 10 percent of dogs.
Atopy begins in dogs 1 to 3 years of age. Susceptible breeds include Golden
Retrievers, Labrador Retrievers, Lhasa Apsos, Wire Fox Terriers, West Highland
White Terriers, Dalmatians, Poodles, English Setters, Irish Setters, Boxers,
and Bulldogs, among others, although any dog may be affected. Even mixed breeds
may suffer from atopy.
Signs generally first appear at the same time as the weed pollens of late
summer and fall. Later, other pollens begin to influence the picture: tree
pollens in March and April; then grass pollens in May, June, and early July.
Finally, the dog starts to react to wool, house dust, molds, feathers, plant
fibers, and so forth. With prolonged exposure and multiple allergens, the
condition becomes a year-round affair. Some dogs have indoor allergies (usually
house dust, grain, mites, or molds), so they may react all year-round from
In early canine
atopy, itching is seasonal and the skin looks normal. Dogs
scratch at the ears and undersides of the body. The itching is often
accompanied by face-rubbing, sneezing, a runny nose (known
eyes, and licking at the paws (which leaves characteristic brown stains on
the feet). In many dogs the disease does not progress beyond this stage.
When it does progress, an itch-scratch-itch cycle develops with deep
scratches (called excoriations)in the skin, hair
loss, scabs, crusts, and secondary bacterial skin infection. These dogs are
miserable. In time, the skin becomes thick and darkly pigmented. A secondary
dry or greasy seborrhea with flaky skin often
develops in conjunction with the skin infection.
canal infections may accompany these signs, or may be the sole
manifestation of atopy. The ear flaps are red and inflamed, and the canals are
filled with a brown wax that eventually causes bacterial or yeast otitis.
Canine atopy, especially when complicated by pyoderma, can be difficult to
distinguish from flea allergy dermatitis, scabies, demodectic mange, food
allergies, and other skin diseases. The diagnosis can be suspected based on
the history, location of skin lesions, and seasonal pattern of occurrence. Skin
scrapings, bacterial and fungal cultures, skin biopsy, and a trial
hypoallergenic test diet should be considered before embarking on an involved
course of treatment for atopy. It is important to treat and eliminate fleas. The majority of dogs with canine atopy are
allergic to fleas and may have an associated flea allergy dermatitis
complicating the picture.
Treatment: The most effective long-term solution is to change the dog’s
living circumstances to avoid the allergen. The atopic dog is usually allergic
to many different allergens, however, and often it is not possible to avoid
exposure to them all.