Skin Allergy (Canine)
Canine skin allergy is a common condition that causes inflamed and itchy skin. Secondary skin and ear infections frequently occur. Testing is available for dog skin allergies, and effective treatments, including allergy injections, may be prescribed.
Common names: Canine skin allergy, Allergic inhalant dermatitis, Airborne allergy.
Scientific names: Canine atopy, Atopic dermatitis.
Diagnosis of Canine Skin Allergy
Atopy usually develops in dogs between the ages of 6 months and 7 years, with 70 percent of affected dogs between 1 and 3 years of age. In certain breeds, signs may begin as early as 2 months of age. Predisposed breeds include terriers, boxers, lhasa apsos, shih-tzus, pugs, golden retrievers, Labrador retrievers, Dalmatians, cocker spaniels, setters, Chihuahuas, miniature schnauzers, Belgian tervurens, shiba inus, and beaucerons. Canine atopy may be more common in females than males, although some studies show no sex predilection.
Incidence/prevalence: Atopy is a common pruritic (itchy) dermatosis that affects 10 to 15 percent of the canine population.
While no geographic distribution is appreciated, clinical signs of dog skin allergy may initially be seasonal or nonseasonal, depending on the offending substances (allergens) involved. Roughly 80 percent of all atopic dogs will eventually have nonseasonal clinical signs. About 80 percent will manifest clinical signs from spring to fall, and about 20 percent begin in winter.
Clinical signs (primary, most to least frequent, scientific term, synonyms)
Pruritus (itch) manifested by licking, chewing, scratching and rubbing, often affecting the feet, flanks, groin, armpits, face and/or ears, Localized or diffuse skin erythema (redness).
Clinical signs (secondary, most to least frequent, scientific term, synonyms)
Salivary staining of fur (from licking), Alopecia (hair loss), Excoriations (linear scabs), scales, crusts (scabs), hyperpigmentation (dark skin) and lichenification (thickened, elephant-like skin) from self-trauma, Secondary pyoderma (skin infection due to bacteria), Malassezia dermatitis (skin infection due to yeast) and otitis externa (ear infection), Conjunctivitis, Facial swelling, Sneezing.
Causes (scientific, common term)
Type I hypersensitivity reaction (allergy) to inhaled or cutaneously absorbed environmental allergens, Genetic predisposition.
Organ systems affected (most to least affected)
Integument (skin), Eye (conjunctivitis), Respiratory (bronchitis or rhinitis, rare).
Skin cytology (impression smear, acetate tape preparations), Ear cytology (if indicated), Deep and superficial skin scraping, Flea combing, Fungal culture (if indicated), Intradermal skin or blood allergy testing.
Other hypersensitivities (food, flea bite, contact allergy) Ectoparasites, Folliculitis (inflammation of the hair follicle) due to bacterial infection, dermatophyte/fungal infection, Demodex), Malassezia dermatitis.
Canine skin allergy, also known as atopy or atopic dermatitis, is caused by an allergic reaction to inhaled or cutaneously (through the skin) absorbed environmental allergens in genetically predisposed dogs. Nearly any breed may be affected, and clinical signs are most common in young dogs between the ages of 1 and 3 years. Signs of a skin allergy include pruritus (itch) manifested by licking, chewing, scratching and rubbing of the feet, flanks, groin, armpits, face and ears.
Localized or generalized skin erythema (redness) may be evident. Brown salivary staining of fur from licking, hair loss, scales, crusts (scabs), and dark and thickened skin may also occur. Secondary skin and ear infections, often due to bacteria and yeast, are very common and contribute to itch. Conjunctivitis (inflammation of the lining of the eye) and sneezing are less commonly observed. Dog skin allergy signs may be seasonal in nature or year-round. Atopic dermatitis is most commonly caused by an allergy to house dust mites, but grasses, weeds, trees, molds, insects and dander are also very important allergens.
The diagnosis of atopy is based on history and on clinical signs combined with allergy testing, which may involve intradermal skin (considered the gold standard) or blood allergy testing. Tests are also performed on the skin to rule out and treat other causes of itchy skin disease, including skin parasites and infection. Allergy injections are frequently prescribed based on the results of allergy testing and, in most cases, reduce the need for other therapies.
Dog Skin Allergy Treatment
Treatments of the home environment to reduce exposure to offending allergens (pollens, molds and dust) are available. High-efficiency particulate (HEPA) air and charcoal filters may be beneficial.
A veterinarian may prescribe medications to treat a skin or ear infection, as well as to target the itch associated with skin allergy. This may include medications by mouth, as well as frequent bathing and ear cleaning. If a skin or blood allergy test is performed to determine what is causing the allergy, immunotherapy (allergy shots or vaccine) may be prescribed that will require injections under the skin.
Pet owners may learn to administer the injections, which are usually given for life. With allergy shots, 50 to 75 percent of atopic dogs have a good (some medical therapy still needed) to excellent (no other therapy needed) response. Clinical improvement may require several months after initiating immunotherapy and may require up to a year in some dogs.
Compliance and follow-up care for the patient with allergic skin disease is very important. An increase in itch or the presence of skin lesions is often due to a secondary infection that requires an examination by a veterinarian for appropriate treatment. Often, if an allergy vaccine is administered, the schedule of injections has to be modified over time, so frequent communication with a veterinarian is necessary.
The prognosis is good for canine atopy, although lifelong therapy for control is needed in most dogs. Relapses with secondary infections are common, and individualized treatment programs are important.
Scott, DW, Miller WH, Griffin CE. Parasitic Skin Diseases. In: Kersey, R, DiBeradino, C, eds. Muller and Kirk's Small Animal Dermatology. Philadelphia: W.B. Saunders, 2001; 490-500.
Medleau, L, Hnilica KA. Small Animal Dermatology: A Color Atlas and Therapeutic Guide. Philadelphia: W.B. Saunders, 2001; 106-109.
Hillier, A, Griffin CE. The ACVD task force on canine atopic dermatitis (I): incidence and prevalence. Veterinary Immunology and Immunopathology; 2001; 81:147-151.
Jeanne B. Budgin, DVM, DACVD
Steven Hansen, DVM, MS, MBA, DABVT, DABT
© 2007. The American Society for the Prevention of Cruelty to Animals (ASPCA)