Causes of Acral Lick Dermatitis
Many factors, or triggers, have been suggested to predispose to or cause acral lick dermatitis, including allergy (atopic dermatitis, food), psychogenic causes, boredom, bacterial folliculitis, foreign bodies, neurologic disorders, local trauma, and joint or bone diseases. Independent of the contributing factor, once the lesion has developed it will contribute to the perpetuation of the compulsive licking behavior.
Signs of Acral Lick Dermatitis
Lesions are usually single but they can be multiple. Large breeds are predisposed (Doberman Pinscher, Labrador Retriever, Dalmatian, Irish setter, Weimaraner, Great Dane, German Shepherd Dog). Onset of lesions can occur at any age, but it is more common in dogs more than 5 years of age. Lesions tend to be recurrent, either at the same or different sites. There is often a history of poor or partial response to many therapeutic treatments. Lesions are created and maintained by constant licking or chewing. Clinically the lesion is characterized by bald, red, eroded or ulcerated, firm, nodular plaque(s).
Diagnosis of Acral Lick Dermatitis
Diagnosis of acral lick dermatitis is based on history, clinical signs, and elimination of other primary causes. It may include skin scrapings, impression smear cytology, and fungal culture (to rule out dermatophytosis). Biopsy of the lesion is helpful to rule out neoplasia (e.g. mast cell tumor). If joint or bone involvement is suspected, radiographs are taken. If there is a history of intense itchiness pruritus (either seasonal or nonseasonal) an allergy test is performed.
Treatment of Acral Lick Dermatitis
Approximately 65% of the cases can be satisfactorily controlled with medical and/or behavior management. However, even if an underlying problem has been identified and treated, concurrent treatment of the skin condition is essential. It is important to treat the frequently associated secondary bacterial infection with appropriate long-term (6 to 8 weeks) antibiotics. Treatment of this condition can be complicated, and in selected cases surgical removal of the affected area is indicated, particularly if the lesion is small, although
complications may develop.
To stop the lick cycle, several devices to prevent licking are recommended : elizabethan collar, bandaging, bad tasting topicals, basquet muzzle. The following drugs aimed to alliviate anxiety are used: phenobarbital, diazepam (Valium), hydroxyzine (Atarax); tricyclic antidepressants: amitriptyline (Elavil), imipramine (Tofranil), and clomipramine (Anafranil).
The successful treatment of lick granulomas relies on a thorough investigation of potential underlying causes and a combination of treatments that may include systemic, topical, behavioral, and surgical methods.
Prognosis for Acral Lick Dermatitis
In most cases a fair to guarded prognosis is given to dogs with acral lick dermatitis. If the underlying condition can be determined, the prognosis improves dramatically.