A hematoma is a swelling caused by blood or fluid collecting under the skin. Both dogs and cats may develop aural hematomas, though they are more common in dogs. An aural hematoma is a swelling on the inner curve of the outer ear, the area known as the pinna. This swelling is uncomfortable for the animal and may cause temporary hearing problems if the pinna swells large enough to partially cover the opening of the ear. If left untreated permanent scarring may occur.
The swelling that forms an aural hematoma is usually caused by a self-inflicted injury from excessive ear scratching or head shaking. This is most common in animals with some sort of ear infection. The animal scratches the ear in an attempt to relieve the discomfort of the ear infection. The scratching or head shaking causes the capillaries to burst allowing blood to seep between the cartilage and the skin of the pinna. Animals with fragile capillaries are at highest risk for aural hematoma.
The most obvious symptom of aural hematoma is swelling of the pinna. The swelling will be warm and soft at first. Over time the skin will gradually thicken and harden. If the condition is not treated the swelling will go down on its own, but the ear will be painful until it does. Even if swelling is not apparent, an animal that is engaging in more head shaking and ear scratching than is normal should be examined by a veterinarian.
Treatment for aural hematoma usually involves surgery to drain the swelling. This can usually be done by your veterinarian. After the swelling has been drained, the veterinarian will cover the site with a bandage, and may fit the animal with a protective collar to prevent further injury during healing. Because aural hematoma is usually the result of another ear condition, the underlying problem must also be treated to prevent recurrence.