Allergies and Your Pet

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Allergic Dermatitis

Allergic dermatitis refers to an allergy that manifests as “itchy skin”. It is the most common reason a pet owner seeks veterinary care. Before appropriate therapy can be instituted, the cause of the allergic dermatitis must be uncovered. Causes of allergic skin disease include flea allergy dermatitis, food allergy and atopic dermatitis (allergy to pollens, weeds, dust mites, etc.) Many pets have a combination of allergies. Control of one or more of the offending problems may result in partial or complete control of your pets’ symptoms.

In many cases allergic skin diseases are complicated by secondary bacterial and yeast infections. Secondary infections occur because of damage to the skin caused by scratching. These infections can cause the itching and irritation to get even worse. For this reason secondary infections must be treated before the underlying cause of an allergy can be ascertained.

Food Allergy Dermatitis

Food allergy dermatitis is an adverse reaction to a dietary ingredient, usually a specific protein in a pet’s diet. The disease is usually non-seasonal, but may be intermittent.

Symptoms most frequently begin in pets 1-3 years of age. In many cases, dogs have eaten the allergenic diet for two years or more before symptoms begin. Signs are highly variable and may include severe itchiness, hair loss, recurrent ear infections, and licking and chewing at the feet.

The most common ingredients that pet’s are allergic to are proteins like beef, poultry and lamb, and grains like corn, wheat and rice. Diagnosis and treatment of food allergies are through food elimination trials. Usually a pet is switched to a novel protein diet, meaning a diet with ingredients that the pet has not been previously exposed to. It is important the pet be maintained on this diet for at least six to eight weeks and not be given any snacks or treats that may contain the offending ingredients.

Atopic Dermatitis

Atopic dermatitis (AD) is a common inflammatory skin disease resulting from a hypersensitivity to inhaled allergens such as pollens, dust-mites, molds, etc. There is an inherited predisposition to developing AD. AD is very common in dogs and affects between 3-15% of the canine population. AD is comparable to human hay fever or seasonal allergies except instead of respiratory symptoms, dogs develop skin disease. Dogs with AD are itchy and frequently have secondary bacterial or yeast infections of the skin or ears. Unfortunately, dogs with AD rarely grow out of their disease. Most dogs with AD are also allergic to fleas and it is essential that absolute flea control be maintained, no matter what therapy is being pursued for the AD.

Steroid Therapy

Steroids (such as prednisone, methylprednisone and depo-medrol) can be useful in relieving the itchiness and discomfort of allergic skin diseases. When used judiciously and in combination with other therapies, they can be safe and efficacious. However, long term, chronic use can have serious consequences. Systemic side effects may be numerous and include behavioral changes (aggression, increased thirst and urination, increased appetite and panting); gastrointestinal problems (vomiting and diarrhea); serious endocrine disorders affecting the liver and kidneys; pets are susceptible to secondary skin infections and recurrent urinary infections. For cases that must be managed with chronic long- term steroids, we recommend close veterinary supervision and occasional blood work to screen for developing endocrine disorders or liver or kidney damage. It is important that the cause of your pet’s allergy is ascertained and appropriate therapy is instituted to reduce the need for steroid use.