Canine Health Menu

Acral Lick Dermatitis

Issue Description
A skin disorder in dogs resulting from an urge to lick the lower portion of the leg. The lesion from the incessant licking is a thickened, firm, oval plaque.
Other Names
Lick Granuloma


Causes
The cause of a lick granuloma is most often psychogenic and is considered to be a form of canine obsessive-compulsive disorder, but other causes include bacterial or fungal infections, demodectic mange, 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.

Psychogenic causes include boredom, stress, or separation anxiety. Lick granulomas are especially seen in large active dogs left alone for long periods of time. The condition becomes a vicious cycle - erosion of the skin from licking leads to pain and itching, which leads to more licking. One theory is that excessive licking causes endorphin release, causing an addiction to licking. The lick granuloma often becomes infected with bacteria, causing a secondary problem.


Commonly Affected Breeds
  • Doberman
  • Great Dane
  • Labrador Retriever
  • Irish Setter and other setters
  • Golden Retriever
  • Border Collie
  • German Shepherd Dog
  • Keep in mind that any breed of dog can develop a lick granuloma, including mixed breeds

  • Symptoms
    Lick granulomas are skin wounds typically located on the distal area of the front leg or hind leg of a dog. Some dogs may have more than one lick granuloma at a time. These lesions usually appear as firm, raised, hairless areas of skin that may be hyperpigmented, or darkened with pigment, due to the dog's chronic licking of the area. The center of the lesion is usually ulcerated, red, and moist, or may be covered by a scab.

    Diagnosis
    In most cases, the diagnosis is made based on the appearance and location of the lesion and the fact that the dog has a compulsion to lick the area. Certain skin tumors, parasites, embedded foreign bodies, and allergies can create lesions that look very similar. In addition, trauma that causes bone fractures or nerve injury can also lead to constant licking, creating a similar lesion. If the diagnosis is in doubt or if the dog does not respond well to initial treatment, fungal cultures, radiographs (x-rays), and biopsies may be recommended.

    Treatment
    Treatment of the primary cause, if known, is essential. The dog should be tested for allergies, and treated accordingly if positive (fatty acids, antihistamines, hypoallergic diet, etc). It may also be necessary to check thyroid levels as hypothyroidism seems to play a role in some cases, particularly in black Labrador retrievers; thyroid medication often will resolve the problem if it's due to hypothyroidism.

    In psychogenic cases, dealing with psychological factors is most important. Factors should be identified such as being left alone all day, being confined, and changes in the household. Correction of these causes may include increased walks, avoiding confinement, and more interaction in the home.

    Drugs may be used until behavior modification has had time to take effect. Antidepressants are most commonly used, including doxepin, amitriptyline, fluoxetine, and clomipramine. If the psychological factors are not corrected, the dog will usually relapse after the drugs are discontinued. Endorphin blockers such as naltrexone can be used to reduce addiction to licking, or endorphin substitutes such as hydrocodone may decrease the urge to lick.

    The lesion should also be treated. Licking can be prevented by the use of Elizabethan collars, bandages, or antilicking ointments (which are bad tasting). Topical medications such as corticosteroids or DMSO may be effective if used early. Small lesions may be injected with triamcinolone or methylprednisolone. Oral antibiotics are used to control infection. Surgery may be performed to remove whole lesions, but there is risk of continued self mutilation to the area afterwards. Other potential treatments include cryosurgery, laser surgery, radiation therapy, and acupuncture. It is important to note that many dogs will lick at another leg, creating a new lick granuloma, if they are prevented from licking at the original one while it heals.

    Overall, lick granulomas are very difficult to treat, with control only being achieved in about 65 percent of cases.


    Dogs
    Horse Herd