One of the most common reasons that cats and dogs visit their veterinarian is the constant scratching or licking that keeps both pets and owners awake at night and distracted during the day. For some pets, this can be a seasonal occurrence, but for the unlucky ones it can become a constant, year-long battle. Allergies form because of an over reactive inflammatory response to an antigen and usually presents as redness, irritation and inflammation of the skin and ears, although the eyes and nasal passages may also sometimes become affected.
The most frequent cause of itchy skin, or pruritis, is the pesky flea. Besides being a household nuisance, multiple flea bites can cause an allergic reaction in some animals that leads to a flea allergy dermatitis. For those animals that develop this allergy, the most important thing is to ensure proper flea control both on their body and in their environment.
Another very common cause of allergic skin reactions in our region is atopic dermatitis (AD), otherwise known as eczema. AD develops in response to common allergens in the environment such as trees, grasses, pollens, molds, house dust mites, etc. There is typically a seasonal variation in the intensity of the pruritis noted, and there may be periods during the year when no itchiness is observed. Skin or blood testing can reveal the cause of atopic dermatitis and allergy shots can be formulated to desensitize the immune system to these stimuli.
Food allergies form as a result of a hypersensitivity to a specific component of the diet, usually a major protein or carbohydrate ingredient such as beef, pork, chicken, soy or wheat. These allergies arise after repeated exposure, so these foods could be ingested for several months to years before the food allergy develops. The pruritis from a food allergy is present all of the time and generally does not exhibit any change in intensity throughout the year. Diagnosis of a food allergy requires a strict food trial using a novel protein and carbohydrate diet for at least 8-10 weeks. If the symptoms resolve on the food trial and return when the original food is given as a challenge, then a diagnosis of a food allergy can be confirmed.
Secondary causes of itchy skin can develop from bacterial or yeast infections that occur as your pet starts to scratch, causing abrasions in the skin that allow surface organisms to invade and cause localized inflammation. Treatment of these infections is required before the underlying cause of the allergy can be determined. Other less common causes of itchy skin can include scabies (sarcoptic mange) and ringworm (fungal) disease.
Unfortunately, all of these itchy skin diseases can appear similar and can’t be diagnosed without a proper history, physical exam, and diagnostic tests by your veterinarian. Treatment options can consist of a combination of steroids, antibiotics, antifungals, antihistamines, parasiticides, immunomodulatory drugs, allergy shots, prescription/restricted diets and flea preventatives. Just remember that allergies are a lifelong problem and can only be managed, not cured.