Thursday, November 6, 2014

Acral Lick Dermatitis

Acral lick dermatitis, also known as lick granuloma, is a self-induced skin lesion. The term acral refers to the legs and feet. Acral lick dermatitis mainly is a problem of dogs, rarely cats. The dog continually licks at one area of the leg, producing hair loss, sores, and thickening of the skin. Typical appearance is a raised, red, hairless, oval patch of skin or skin lump found over the front surface of one leg. Occasionally, more than one leg may be affected. The most common locations are over or near the carpus (“wrist”) of the front foot or just below or above the hock on the rear leg. Breeds most likely to develop acral lick dermatitis include the Doberman pinscher, Great Dane, Labrador retriever, Irish setter, golden retriever, and German shepherd, but any breed of dog can be affected.


Males are affected twice as often as females. The condition may appear at any age however most dogs are over 5 years of age when presented for treatment. Although several conditions that cause discomfort of the skin can cause persistent licking, in many dogs with acral lick dermatitis no underlying problem can be found. In these cases, acral lick dermatitis is considered a psychogenic disease; that is, it is caused by a behavioral disorder. For example, sometimes excessive licking or chewing can result from boredom or can be used as attention-seeking behavior; sometimes anxiety is the stimulus for stereotypic behaviors like repetitive licking. Stereotypic behaviors are excessive, repetitive behaviors engaged in to relieve psychological distress such as boredom or anxiety.


Causes

The most common cause of lick granuloma appears to be psychological, related to stress, anxiety, separation anxiety, boredom, or compulsiveness. Lick granulomas are especially seen in large active dogs left alone for long periods of time. It is often considered to be a form of canine obsessive-compulsive disorder. One theory is that excessive licking causes endorphin release, which reduces pain and makes the dog feel euphoric temporarily. That effect then in turn causes an addiction to licking.
But other less common causes include bacterial or fungal infections, trauma causing nerve damage, allergies, or joint disease. Hot spots may also lead to the formation of lick granulomas.
Many large breed dogs appear to be predisposed, as well as golden retrievers and other bird dogs. It can occur at any age, though most dogs are older than five years of age. Seventy per cent of the time it appears on one of the dog's left legs. Arthritic and mobility problems in older dogs give them more time to lick and over-groom themselves.
Frequent formations of lick granulomas in the same area due to the constant licking will cause hardening, caluse formation, hair loss (the hair may stop growing back), and hyperpigmentation to that area. The condition becomes a vicious cycle – erosion of the skin from licking leads to pain and itching, which leads to more licking. Lick granulomas sometimes become infected with bacteria, causing abscessed areas or fistulous tracts (furuncles).

Signs Look For
  • Persistent licking or chewing at one area on the foot or leg.
  • Hair loss, irritated skin, and eventually a raised, completely hairless, shiny, reddened area of skin.

Diagnosis

Several other skin conditions may appear similar to acral lick dermatitis. These include skin tumors, granulomas (masses due to chronic inflammation), and deep bacterial or fungal infections. In addition, several conditions that cause pain or itching can be involved in the development of lick granulomas, since dogs will lick areas where they feel tingling or discomfort. Depending upon the appearance of the skin lesion and your pet’s history, your veterinarian may need to run several tests to check for similar conditions and underlying disorders, including skin scrapings, bacterial or fungal cultures, and skin biopsies. In some cases, x-rays may be warranted to look for joint or bone disease, such as arthritis, or bone infections that can cause pain and therefore cause a dog to lick over the painful area incessantly. A history of trauma or surgery in the area might indicate possible nerve damage as a source of discomfort. A variety of conditions that cause itching can contribute to the development of acral lick dermatitis; these include allergies, skin infections, and skin parasites (fleas, mange, etc.). If no underlying disease can be found, then by exclusion, psychogenic factors are assumed to be the cause of the dog’s constant licking.
Therefore, the first step in evaluating a dog thought to have acral lick dermatitis is to perform basic tests to assess for other contributory medical and skin conditions (above). Once acral lick dermatitis is confirmed to be the problem, a very valuable form of evaluation is consultation with a veterinary behaviorist. These are veterinarians who specialize in assessment and treatment of behavioral disorders such as acral lick dermatitis. While animal behaviorists are sometimes derided, there are specialty-trained veterinarians whose focus of practice is entirely animal behavior, and their input and recommendations can be lifesaving.

Treatment

There are many approaches to treating acral lick dermatitis, and some trial and error is usually needed to find the best treatment for an individual dog. Since deep bacterial infections of the skin usually are present as well (secondary problem due to the damage of licking), antibiotic pills are usually given for several weeks. The affected skin area can be treated directly with a variety of medications, including topical treatments and injections. Bitter-tasting topical solutions are sometimes applied to discourage licking.
Most treatments that are applied to the lesion are aimed at altering the sensation in the skin. Agents used include corticosteroids, dimethyl sulfoxide (DMSO), capsaicin, anti-inflammatory drugs, and antihistamines. Additional treatments aimed at reducing itching or painful sensations include acupuncture, laser surgery, or cryosurgery. Removal of the lesion with conventional surgery, laser surgery, or cryosurgery is also advocated by some veterinarians. Some degree of relief can also sometimes be brought about by frequently bandaging the leg and/or placing an Elizabethan collar on the dog to break the cycle of licking-itching.
Behavioral components of the condition also need to be addressed. Boredom can be alleviated by increasing playtime, introducing another animal as a playmate, reducing confinement time, or keeping the pet occupied with toys such as those with openings for treats (e.g., Kong-type toys). Several behavioral modification training techniques can be used. Stressful conditions should be eliminated, when possible. Antidepressant and antianxiety drugs may also be helpful in some dogs, and these can be prescribed by your veterinarian or a veterinarian specialized in behavioral medicine.
Be diligent and persistent with treatment. Hair regrowth and reduced compulsion to lick happen very slowly (weeks to months).

Precautions

  • Avoid blaming or acting exasperated with a dog with acral lick dermatitis. Unfortunately, compulsive licking can truly be exasperating, but yelling at or punishing dogs for doing this simply does not register with them and often can make them more compulsive, which worsens the problem. In other words, harsh words and punishment for licking behaviors tend to be totally counterproductive.
  • Don’t assume that the problem is entirely in the skin, or entirely in the dog’s mind. Oftentimes, a combination of behavioral factors and skin factors is to blame for acral lick dermatitis. 

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