Allergic Skin Disease

One of the most frequent reasons pet owners visit their veterinarians for, is to treat and consult over allergic skin disease. The most common clinical signs are: scratching, licking and chewing at their skin and feet, shaking their heads, scales and flakiness of their skin, discoloration of the hair and skin, and hair loss (alopecia).

There are many causes to allergic skin disease:

Inhalent  allergies occur when a patient has an allergic reaction to things that are in the air. The most common of these is pollen. Pets that have inhalant skin disease tend to have clinical signs that are seasonal, or are worse at certain times during the year. This is by far the most common cause, and pets tend to chew at their feet, have ear infections, and scratch to the point where secondary bacterial infections develop which aggravates the itchiness. Most pets develop skin infections as a result of scratching and licking. The itchiness comes first. This is why it is important to identify the cause of the discomfort and not just treat the infections.

Food allergies are an important component in the skin puzzle. Oftentimes they are not the sole cause of the problem, but they contribute to the symptoms. Pets that have food allergies tend to develop these at early ages and have hairloss in the backside , under the tail. Food elimination trials can be implemented to address this potential cause skin discomfort.

Ectoparasites, ie. fleas and ticks are a smaller proportion of the allergic puzzle with the advent of effective products to control  them. Thankfully, we see very few cases of flea bite dermatitis anymore. It is important to exercise good preventive measures to control fleas and ticks, especially in allergic pets.

Contact dermatitis occurs when a susceptible pet is exposed to something they are allergic to by direct contact. The most common areas of the body affected are the feet. A pet that is chewing at their feet and nowhere else, is likely allergic to the grass they are exposed to. Another common sign is redness in the groin area because it is the most hairless part of the body and the part most likely to contact the grass, when a pet lays down. Other possible causes of contact dermatitis are rugs, or towels and even the laundry detergent used to clean the pet’s bedding.

Treatment is aimed at controlling the itch. This is achieved with topical sprays and shampoos, antihistamines, and sometimes steroids. Steroids should be used with caution, and only on a short term basis because of potential long term side effects. Antibiotics are used to control secondary infections and must be continued until the infection is cleared. This could take 2-6 weeks.
Underlying conditions such as hypothyroidism need to be addressed and treated as well.

Diagnosis is made by trial and error, and allergy testing. This can be done with blood testing (RAST) and intradermal skin testing, usually done by a dermatologist. Food trials can be done without expensive testing by trying novel diets. The definition of a hypoallergenic diet is one protein and one grain. If a food trial is instituted, the pet must get nothing other than the food for 30-45 days for an objective assessment to be made.