Aural Contact Dermatitis in Animals

Aural contact dermatitis commonly affects the concave aspect of the pinna, likely because the concave aspect lacks hair. Topical ear medications, particularly those containing aminoglycosides and/or propylene glycol, are common causes of aural contact dermatitis in animals being treated for otitis externa. Lesions can develop 1–7 days after starting treatment. Contact dermatitis can also result from ointments applied transdermally to the concave aspect of the pinnae.

Clinical signs of aural contact dermatitis include the following:

• erythema

• edema

• papules that may coalesce to form plaques

• erosions

• ulcerations

• pruritus (variable)

• pain (variable)

Diagnosis of aural contact dermatitis is based on the following:

• detailed history, including any recent topical therapy

• physical examination

• resolution of clinical signs after discontinuation of all topical medications

• recurrence of clinical signs after drug challenge

Definitive diagnosis is rarely achieved, because most clients are reluctant to trigger a recurrence of clinical signs and discomfort via drug challenge.

Treatment of aural contact dermatitis involves avoidance of the topical medication suspected of causing the dermatitis, as well as administration of corticosteroids (topical and/or oral) to control inflammation. If treatment of otitis externa is to be continued, a product with different active ingredients and vehicles should be used.