These small to large fluid-filled swellings develop on the concave surface of the pinnae in dogs, cats, and pigs. The pathogenesis for the development of the lesions is unknown, but head shaking or ear scratching due to pruritus is almost always involved. In dogs, the condition is seen with atopy and food allergy, in which the ear canals are the primary sites of allergic inflammation, pruritus, and secondary infection. In pigs, sarcoptic mange, pediculosis, and meal in the ears (from overhead feeders) have been implicated as a cause of head-shaking that has led to auricular hematomas. Bites from other pigs also may be at fault (see Diseases of the Pinna: Necrotic Ear Syndrome in Swine). Treatment is surgical to allow drainage. After draining and flushing, several mattress sutures can be placed to eliminate the pocket. The addition of a drain made out of a teat tube, piece of soft urinary catheter, or IV catheter increases the success rate of surgery. Drainage and glucocorticoid instillation are successful in ~50% of cases. Drainage is best obtained with a butterfly connection or an IV catheter. Glucocorticoids are instilled to fill the cavity without causing skin distention. A short course of a low anti-inflammatory dosage of oral glucocorticoids is commonly added to this treatment.
Last full review/revision July 2011 by Sheila Torres, DVM, PhD, DACVD; Scott A. Dee, DVM, MS, PhD, DACVM