Paw Licking & Allergies |
| Paw-licking and -chewing are common signs of disease
in dogs. Many owners assume these behaviors are normal and fail to recognize
the extent of the problem. Genetics play a role in many cases, but overbreeding
is not a specific cause. Purebred and mixed-breed dogs can chew any combination
of paws, but chewing both front feet is most common. The degree of itch
and obsession with the feet can vary with time of year, weather, age, diet
and other factors.
The most common cause for the itch you describe is atopic dermatitis, or inhalant allergy. This is similar to hay fever in humans except that the result is usually foot-chewing rather than respiratory signs. Allergens include dust and dust mites; pollens from trees, weeds, grasses and other plants; molds; mildew; animal or human dander, including wool; and insects. Usually more than one substance is involved. Some atopic dogs also develop skin irritation on the face, forelimbs and armpitis, among other places. Atopy also frequently causes or contributes to chronic ear and eye problems. Occasionally, dogs develop respiratory signs, such as sneezing or nasal discharge, reverse sneezing and wheezing, breathing difficulty, cough or exercise intolerance. A dog with a flea allergy also will chew its paws. Obviously, any irritating substances can also initiate chewing, including soaps, shampoos, chemicals and foreign bodies. Infections of the skin, hair, nails and nail beds can
be the primary cause of foot-chewing and are almost always present as secondary,
complicating factors in allergic situations. Infectious agents can include
bacteria, yeasts, fungi and demodectic mites. Many of these organisms
are normally present on the skin and only cause disease under certain conditions.
Allergies can cause constant licking and subsequent swelling of the feet
and accumulation of debris, creating a moist, warm environment in which
overgrowth of these organisms can occur. Chewing and superficial infection
allow deeper penetration of the organisms into the tissues, creating a
very itchy cycle. If the suspected allergy is treated but not the secondary
(or primary) infections, it is unlikely
Diagnostics to help define the problem beyond simple allergy include thyroid testing, cytology (examining smears of the skin and nail beds under a microscope for infectious agents) and skin scrapings with microscopic exam to rule out mites. Blood or skin testing can be done to specifically identify offending allergens, thus allowing an owner to decrease exposure if possible. Bacterial cultures may be needed when bacteria are suspected based on cytology or biopsy results and antibiotics don't clear up the problem. Culture of the bacteria allows sensitivity testing to determine which antibiotics are likely to give the best results. This can be especially important in chronic cases in which long-term treatment may be needed. Trial courses of medications can also be used once it is deemed safe. As with allergies in humans, the situation can be complex and may require trying several different medications to find the best drug or combination of drugs. Treatment will vary depending on the specific diagnosis. Dogs with low thyroid results (hypothyroidism) should be supplemented. Specific infections should be treated. This treatment might include orally administered medications and/or topically applied medications, dips, scrubs and soaks. I have found that scrubbing the feet two or three times weekly with antibacterial/antifungal shampoos can be extremely helpful — 4 percent chlorhexidine is my favorite active ingredient. The feet should be dried well after scrubs. Allergens identified on testing should be avoided or eliminated from the dog's environment whenever possible. Keeping the dog inside more and avoiding walking in grass, weeds or brush may also help, reducing topical and oral exposure to potential allergens. Some dogs may need desensitization injections; the ingredients should be chosen based on allergy testing and likelihood and duration of exposure. Flea control needs to be nearly perfect in allergic dogs. Dogs with atopy (inhalant dermatitis) may require further anti-inflammatory treatment. This is where corticosteroids such as prednisone come into the picture. It is important to realize that steroids are not inherently "bad" medications; in fact, they are essential in the short-term and emergency treatment of many patients. The itch relief gives damaged and infected tissues a chance to heal by breaking the lick cycle. Long-term reliance on steroids and failure to pursue other causes of the itching should be discouraged. Unfortunately, a few dogs need steroids for sustained allergy relief. Even in these individuals, efforts should be made to use the steroids only intermittently and at the lowest possible dose, and to spare the need with other medications and supplements whenever possible. Antihistamines may provide complete or at least adequate relief for many dogs, especially when used in combination with omega-3 fatty acid supplements. Each dog is different, so you may have to try several types and dosages to find the best one. Food allergy also has to be considered because it can cause the same signs as atopy. Allergy can develop to any food, though protein sources are most often the problem. Hypothyroidism can also contribute to many allergic conditions. Veterinary dermatologists are available to address non-responsive or complicated cases. By Michael Abdella, DVM |
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