Atopy can be considered the
canine equivalent of hay fever. It is quite common,
affecting around 10 per cent of dogs. Animals with
this condition become sensitized to substances (allergens)
in the environment, that are inhaled or absorbed
through the skin (and which cause no problems for
non-atopic animals). The resultant allergic reaction
is primarily seen as extreme itchiness (pruritis).
The main allergens involved
are house dust mites, house dust, human dander,
feathers, molds, and pollens from trees, weeds,
and grasses. Atopic dogs are also prone to seborrhea,
secondary bacterial skin infections (pyoderma) and
probably yeast (Malassezia) infections as well
How is atopy inherited?
The exact mode of inheritance is unknown. There
is a strong breed predilection for this condition,
and marked familial involvement (ie. if both parents
are allergic, there is a very strong likelihood
the offspring will be as well).
What breeds are affected
This condition occurs in many breeds. It is
most common in the following: Boston terrier, boxer,
Cairn terrier, Chinese shar-pei, dalmatian, English
setter, golden retriever, Irish setter, Labrador
retriever, Lhasa apso, miniature poodle, miniature
schnauzer, pug, Scottish terrier, West Highland
White terrier, and wire-haired fox terrier.
For many breeds and many disorders,
the studies to determine the mode of inheritance
or the frequency in the breed have not been carried
out, or are inconclusive. We have listed breeds
for which there is a consensus among those investigating
in this field and among veterinary practitioners,
that the condition is significant in this breed.
What does atopy mean to
your dog & you?
The condition is usually first seen between
1 and 3 years of age, although it may develop as
late as 6 or 7. Initially atopy may be seasonal
(eg. from spring to fall) but most affected dogs
eventually have signs all year round.
Dogs with atopy are very itchy.
The areas most affected are the face, paws, lower
legs, groin, and, less often, the ears and eyes.
In addition to scratching themselves with their
hind feet, they often lick or chew the affected
areas, or rub along the carpet to scratch the face
or ears. The intense itching can make them irritable
and less tolerant of being handled.
Initially, there are no apparent
skin abnormalities, except possibly slight reddening,
even though the dog is clearly itchy. (This is important
because in other conditions there is often a rash
or some visible lesion.) Over time, lesions develop
as a result of the scratching and self-trauma, bacterial
or yeast infections, and seborrhea, all of which
can contribute to the objectionable odor of these
dogs. The skin becomes reddened and eventually darkened
(hyperpigmentation), abraded, thickened, and wrinkled,
with loss of hair and bronze staining from saliva.
The concept of "allergen
load" is important in understanding and treating
this disorder. Atopic dogs are generally allergic
to more than 1 agent. A small amount of allergens
may be tolerated without developing a reaction,
but an increase in any one of those (ie. an increase
in allergen load such as occurs during pollen season)
may push your dog over the edge to an allergic reaction
of extreme discomfort.
How is atopy diagnosed?
There are many skin diseases that cause itching,
and they can all look rather similar on physical
examination. Your veterinarian will ask you questions
about your dog's diet, environment, any kind of
skin care you are already providing, whether any
other pets or people in the house are itchy, where
and how quickly did the skin lesions start, and
is there any seasonal pattern to the itching. The
answers, as well as the age and breed of your dog,
will provide diagnostic clues. For example, itching
that begins suddenly and rapidly gets worse, is
more typical of a flea allergy, scabies, or a drug
hypersensitivity. Itching that begins insidiously
and gradually worsens, is seen more often with atopy,
food allergy, bacterial or yeast skin infection,
and seborrhea. Skin infections and seborrhea commonly
develop secondary to atopy and may have to be cleared
up before your veterinarian can diagnose atopy.
Diagnostic tests may include
multiple skin scrapings and smears (for mites or
yeast infection), fecal examination (for parasites),
skin biopsy, skin testing (for allergies to different
substances), elimination diets or change in environment
(if food or contact allergy is suspected),
How is atopy treated?
Atopy can be satisfactorily controlled in at
least 90 percent of affected dogs. There are 3 components
to successful treatment, which will be life-long
and will likely require modification from time to
time. A combination approach is generally most effective.
1- reduction in exposure to
allergens. This requires identification of the substances
to which your dog is sensitive (ie. allergy testing).
You may be able to avoid some allergens altogether
(if your dog is allergic to feathers or tobacco
smoke for example), and reduce exposure to others
(by keeping your pet out of carpeted areas to reduce
house dust mite exposure for example). Your veterinarian
will discuss this with you, in conjunction with
the results of your dog's allergy testing.
2- hyposensitization (immunotherapy
or "allergy shots"). This is recommended
when the allergens involved can't be avoided, and
your dog has clinical signs more than 4 to 6 months
of the year which can not be kept under control
with medical therapy. Immunotherapy is carried out
after your dog's allergens have been identified
by allergy testing. Injections of low doses of the
appropriate allergens are given at short intervals
at first, and then boosters given as needed when
clinical signs begin to reappear.
3- medical treatment. Long
term management may include gentle moisturizing
anti-pruritic (control itching) shampoos, fatty
acids, antihistamines (more likely effective when
given as preventative), and short-acting corticosteroids
on alternate days (given for short periods at times
when there are flare-ups, to mimimize the potentially