What Makes Your Pet Itch?

Common Pollens               Dust Mites

         Introduction

Dermatological disorders are very common in the dog, cat and horse. In fact, a recent survey among veterinarians revealed that dermatological conditions are the most frequently seen problem on a day-to-day basis in their practice.

In companion animals, parasites, allergies and hormone disorders are most commonly manifested as dermatological conditions. In the dog, allergic disorders are the principal cause of chronic skin problems, which require professional, veterinary intervention. Atopic dermatitis or “Atopy” is a skin disease characterized by pruritus that is caused by an allergy to substances (allergens) in the environment encountered primarily by percutaneous absorption or inhalation of the allergen. It should be noted that atopy or allergies are encountered far more frequently in the dog, than any other companion animal. The most common environmental allergen is the house dust mite allergen. Atopy is increasing in prevalence among dogs and affects nearly 20% the dog population.

Allergies in pets tend to be inherited, just as they are in humans. If the parents are allergic, there's an increased predilection that the offspring will be as well. That's why we see that allergies are very common in some breeds of dogs and not as common in others. Typically, dogs that are predisposed to allergies (atopy) generally develop symptoms between 6 months and three (3) years of age. Depending on what they are allergic to, some dogs may suffer from seasonal allergies, while some may itch and scratch all year long. The biggest offenders are the common dust mite. As atopic dogs age, their symptoms tend to become less seasonal as they become allergic to more substances, eventually leading to year-round symptoms.

Example of canine atopic dermatitis in a canine with severe facial trauma(left).

Intradernal Skin Test (IDST) site on the same canine patient with strongest reactions with D. pteronyssinus and D. farinae allergen(dust mites)(right).
Pictures Courtesy of Wayne Rosenkrantz, DVM, ACVD - Animal Dermatology Clinic

         Common Symptoms in Your Pet

As discussed earlier, atopic dermatitis is often observed within the first three years of life. Dog owners may notice that their dog grooms excessively, with licking or chewing of the paws, face and abdomen. The ears may be red and hot to the touch. The result of this itchiness (pruritus) is that the dog may be presented to the veterinarian on a number of occasions within the first 24 months of life for a variety of minor skin conditions. Between these episodes, the skin and the coat can look remarkably normal. As the animal ages, the condition generally becomes more severe which usually requires medical intervention (e.g., antihistamines, glucocorticoids, antibiotics, etc.). With increasing pruritus, alopecia (hair loss) and redness of the skin becomes evident with secondary infections (bacterial or yeast) becoming more common.

Many dog owners scold their dogs for scratching and licking behavior. Some dogs will perform most of their chewing and licking in private or while left alone when the owners are gone. Luckily, there are some telltale signs that help us to identify the pruritic or “itchy” dog. Saliva staining is commonly seen in dogs as a red-brown staining of their light-colored hair in the groin, armpits and paws. In addition, with chronically affected dogs, the skin itself will also change color. Instead of being a pink color, a black mottling (hyperpigmentation) and thickening (lichenification) can slowly develop at these sites of self-trauma. These same sites are more prone to becoming secondarily infected by surface bacteria or yeast.

Paw Licking (above)
Significant secondary Malassezia
yeast pododermatitis associated
with atopic dermatitis.

         Diagnosis and Treatment

Fortunately, there are now many options to diagnosing and effectively treating allergies in your pets. Your veterinarian can perform allergy testing which is identical to the “skin tests” or in vitro blood allergy tests performed on humans. Your veterinarian may need to perform other diagnostic tests in order to “rule-out” other skin diseases, which may further confirm the diagnosis of atopy or allergies in our dog. Your veterinarian may recommend antihistamines, antibiotic or anti-yeast therapy, glucocorticoid therapy and perhaps even fatty acid supplements. In addition, your veterinarian may recommend immunotherapy (allergy shots) for more continuously itchy cases. In most all cases, your veterinarian will suggest an environmental control (avoidance) program as an adjunct to medical intervention.

         Preventative Care

Since environmental exposure to allergies is important in the development and to the level of severity of the disease in your pet, environmental control (avoidance) becomes an important component in the overall management of the disease. Environmental control can be very helpful as one of the most important factors for reducing the severity of symptoms and improving patient outcomes. The success of treatment depends on several factors including the overall health of your pet and the pet owner’s commitment to therapeutic intervention. In general, the steps to successful allergy treatment involve the following: (1) making every effort to avoid or reduce and if possible avoid) the allergens in the environment, (2) giving medication(s) to control symptoms and (3) identify the specific allergens that the pet is sensitive to, followed by specific allergen immunotherapy.