The auricle, or pinna, is the expanded external portion of the ear that collects sound.  It is made up of a delicate, curved plate of cartilage covered with thin layers of muscles and blood vessels and sandwiched between two layers of skin.  Aural hematomas result when the fragile plate of cartilage is fractured and damaged blood vessels within the cartilage leak.  The result is a soft, fluctuant swelling most noticeable on the inner (concave) surface of the pinna.

Most aural hematomas are self inflicted and develop secondary to vigorous head shaking or scratching. This behavior is a reaction to irritation associated with inflammation of the external ear canal. The most common causes of inflammation are foreign bodies, atopy (inhalant allergies), food allergy, bacterial infection, yeast infection, and ear mites.  Rarely, hematomas result from underlying immune-mediated disease, plasma cell chondritis, or increased capillary fragility due to systemic disease.

Objectives of treatment are to:

Identify and eliminate the source of ear irritation.   This is accomplished through physical and otoscopic examinations. Due to the pain associated with ear disease, many cats need sedation to facilitate a thorough examination of their ear canal. Foreign material can be removed from the ear canal and samples collected to identify the cause of the disease. Appropriate medications can be prescribed to treat the condition. Signs of systemic disease require additional diagnostics including blood work, Felv/FIV testing, radiographs, and/or biopsy.

Surgically drain the hematoma under general anesthesia. The fluid is removed and sutures are placed to appose the cartilage and prevent reoccurrence. These sutures will remain in place for 3 weeks to allow adequate time for the cartilage to heal.  Some small hematomas may resolve without surgical intervention if the underlying cause has been eliminated.  However, second-intention healing may cause deformation of the pinna with a poor cosmetic result.

If treatment is delayed, the fibrin clot within the hematoma will begin to contract, causing the ear to become firm, thickened and cauliflower-like in appearance.

Prognosis for cosmetic appearance is guarded and recurrence is unpredictable.  Best results are obtained when the underlying cause has been eliminated and the hematoma has not been allowed to begin the process of fibrosis.