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Name
Inhalant Allergy, Canine and Feline
Short Description
Atopy
Affected Animals: Dogs, cats, humans. In canines, females are
affected more commonly than males. Geographical location can
influence the animals affected. Dog breeds predisposed to atopy
include beagles, Boston terriers, Cairn terriers, Chinese shar-peis,
dalmatians, English bulldogs, English setters, golden retrievers,
Lhasa apsos, miniature schnauzers, Scottish terriers, West Highland
white terriers, and wirehaired fox terriers. There are no documented
predilections in cats.
Overview: Like humans, dogs and cats can be allergic to
pollens, spores, and other allergens that appear in the environment
seasonally, as well as substances found within the house such as
dust and animal dander. While people tend to respond to these
various allergens by sneezing and developing watery eyes, animals
react by getting very irritated, itchy skin. This leads to constant
scratching and chewing which can cause trauma to the skin and
extreme discomfort. Generally, symptoms worsen with age and can be
controlled, but not eliminated.
Clinical Signs: Pruritus is the most common symptom. Secondary
skin lesions due to the resulting self-trauma will have a pattern of
distribution within interdigital spaces and on the muzzle or face,
carpal and tarsal areas, axilla, groin, periocular, and pinnae.
Symptoms are initially seasonal and usually worsen with age.
Recurrent pyoderma and otitis externa are commonly noted. Skin
lesions can include erythema, alopecia, scales and crusts, fur
stained with saliva, hyperpigmentation, and lichenification. These
symptoms usually respond well to corticosteroids. Cats may vary
widely in their symptoms, which can include eosinophilic granuloma
complex, miliary dermatitis, symmetrical alopecia, facial pruritus,
and behavior changes. Any animal with pruritus should be evaluated
for the possibility of atopy.
Symptoms: Common symptoms include an often intense itching,
which results in the animal's constant scratching and biting of the
irritated skin. Secondary skin abnormalities will result from the
trauma caused by scratching the itch. These include redness, hair
loss, crusts and scaling, ear problems, fur that is stained brown
from saliva, and skin infections. Cats may vary widely in their
symptoms, which can include facial itchiness, hair loss in equal
patterns, raised and open sores, and bumps with bloody scabs.
Description: Clinically known as atopy, inhalant allergy is a
hypersensitivity to environmental allergens manifested through
irritation of the skin and ears. Atopy occurs in 10 to 15 percent of
the dog population and tends first to occur when the canine is
between one to two years old. Feline atopy can occur at any age. It
is not uncommon for animals to have atopy in conjunction with other
allergies such as food hypersensitivity and flea allergy dermatitis.
Treatment involves the avoidance of the allergens, medications, and
sometimes immunotherapy, or allergy shots. Atopy is a lifelong
disease that can not be cured. Thus, atopic animals will need to
receive treatment for the rest of their lives, and treatment plans
may be only somewhat effective
Diagnosis: The veterinarian will ask the owner about the
animal's history of symptoms. During the physical examination, the
presence of itching and skin lesions will be assessed. Before
concluding a diagnosis of inhalant allergy, the veterinarian will
need to rule out other skin diseases including food
hypersensitivity, flea allergy dermatitis, sarcoptic mange, contact
dermatitis, and yeast infection of the skin. Diagnostic procedures
can include bloodwork and urinalysis, and skin scrapings, and fungal
cultures. Intradermal skin testing is believed to be the most
accurate of the allergy tests; this procedure should be performed by
an experienced veterinarian or by a veterinary dermatologist. There
are also blood tests which, while they are unreliable for felines,
may provide information about inhalant allergies for canines.
Prognosis: Inhalant allergy is a life-long disease that
tends to worsen with age. Therefore, treatment is required for the
duration of the animal's life. Owners may elect euthanasia for
animals with severe allergic skin disease and disappointing
responses to therapy.
Transmission or Cause: The most common allergens include airborne
pollens such as grasses, trees, weeds, and fungal spores. Indoor
allergens include natural fibers such as wool and household dust
mites. In addition, some animals are allergic to the dander from
other animals in the same dwelling.
Treatment: Treatment involves the avoidance of identified
allergens when possible. Essential fatty acid supplements, given at
higher doses, can help control the symptoms. Medications can include
antihistamines, corticosteroids, and immunotherapy, or allergy
shots. Owners should be aware that long-term use of corticosteroids
can result in complications including iatrogenic Cushing's disease,
or excessive levels of glucocorticoids in the body, diabetes
mellitus, and worsening bacterial or fungal skin infections. Allergy
shots are formulated specifically for individual animals and are
administered by an injection under the skin. Improvement of symptoms
can take three to six months in the canine and up to one year in the
feline. Immunotherapy is successful in reducing itching in 60 to 70
percent of dogs and 73 percent of cats. In addition, shampoos and
topical products may be beneficial.
Prevention: Prevention includes avoiding known allergens by
maintaining a dust-free house, closing windows, and keeping the
animal indoors during high pollen season. It is also important to
minimize complicating factors such as fleas, a dirty haircoat, and
skin or ear infections.
