Acral Lick Dermatitis

Also known as: Acral Lick Granuloma — Acral Pruritic Nodule — Lick Granuloma

Introduction

Acral lick dermatitis results from an urge to lick the lower cranial portion of a limb, producing a thickened, firm, oval plaque.

The condition may be organic or psychogenic in origin and potential organic causes should always be excluded before a diagnosis of an obsessive-compulsive disorder is made.

It might be that a predisposing cause or initial insult induces attention and licking, and exposes sensory nerves in the lower epidermis, resulting in a continuous stimulus to lick.

Stress and medical triggers can both contribute to the development of acral lick dermatitis in an individual dog. These may include: hypersensitivities, ectoparasites and other pruritic conditions, fractures, implants, osteomyelitis, arthritis, intervertebral disk disease, neurological lesions.

The stereotypical behaviour is often inadvertently reinforced by the attentive owner.

Large breeds such as Doberman Pinschers, Great Danes, Golden Retrievers and Irish Setters are more commonly affected, and males are twice as often affected than females.

Damage is done to the skin and it is inevitably secondarily infected, usually with Staphylococci but sometimes with gram-negative bacteria and anaerobes. Chronic folliculitis and furunculosis are important and result in further inflammation, fibrosis and self-trauma.

Clinical Signs

The lesion commonly occurs on the cranial aspect of the forelimb in the carpal or metacarpal areas. Multiple lesions on more than one limb may sometimes be present.

There is firstly alopecia and saliva-staining, then erosion of the skin, and a firm, well-circumscribed, often pigmented and sometimes ulcerated, plaque.

Diagnosis

A thorough history and clinical examination should be performed to help identify any underlying conditions.

Bacterial and fungal cultures, skin scrapings and cytology should be performed to investigate any dermatological diseases.

Radiography of the affected limb can be performed, and there are often periosteal reactions in the underlying bone.

Biopsies should always be taken, and histopathology performed to rule out other differentials.

Culture and sensitivity should be performed to identify suitable antimicrobials.

Electrophysiological studies have suggested that there is a mild distal sensory polyneuropathy, which may cause or be a result of the disease.

Treatment

Any predisposing causes should be addressed.

Behavioral acral lick dermatitis is diagnosed by exclusion, and treatment of these dogs involves a combination of behavioural management with training and medication, and treatment of the skin disease.

Behavioural management include: identifying and prevention situations and stimuli that lead to conflict, stress, anxiety or boredom. This can be combined with medical therapy such as: clomipramine or selective serotonin reuptake inhibitors.

These drugs should be used with care as they can lead to sedation, tachycardia, mydriasis, dry mouth, gastritis, nausea, and are contraindicated in hepatic and renal disease. Benzodiazepines can also be used, but can lead to sedation and ataxia.

Dog appeasing pheromone (DAP) has shown to be as effective as other drugs in some studies.

For the skin lesion, antibacterial therapy is essential. The antibiotic should be broad spectrum or chosen according to sensitivity results. Long-term treatment is necessary, and may be up to 4 months, especially if there is furunculosis and excessive scarring.

Topical treatments available include various steroid and antibacterial ointments.

An effort should be made to deny access to the area until the lesion has resolved, and this might involve using an Elisabethan collar, a sock or a bandage.

Lasers can be used to debride the lesion and accelerate healing.

Searching for an underlying cause is paramount in the treatment of this condition, as otherwise signs will recur once antibiotics and preventative measures are stopped.

Prognosis

Treatment is often difficult as the condition can combine various behavioural and medical problems.

A guarded prognosis should be given to owners before beginning treatment.

Acral Lick Dermatitis Learning Resources
Flashcards Test your knowledge using flashcard type questions	Small Animal Dermatology Q&A 17

References

Landsberg, G. (2003) Handbook of behavioural problems of the dog and cat Elsevier Health Sciences

Muller, G. (2001) Small animal dermatology Elsevier Health Sciences

Harvey, R. (2009) A colour handbook of skin diseases of the dog and cat Manson Publishing

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