Canine Aural Hematoma

What is an aural hematoma?

Hematomas are collections of blood or serum (the yellowish, clear fluid portion of the blood) within the tissues. Hematomas that are more than a couple of days old may also contain blood clots. An aural hematoma is a hematoma that develops beneath the skin on the ear flap. This part of the ear is called the pinna. It consists of a thin layer of cartilage (which gives the pinna its shape and structure), with skin on either side, on the outer and inner surface of the ear flap.

Aural hematomas cause obvious swelling and thickening of the pinna. The swelling is hot and painful when it first develops. Without treatment, healing of the hematoma may disfigure the pinna, causing shrinkage and distortion. A cauliflower ear is the result.

What causes aural hematomas?

Hematomas develop when blood vessels beneath the skin are ruptured and leak blood or serum into the surrounding area. In most cases aural hematomas result from persistent scratching of the ear or shaking of the head. The most common reason why dogs scratch at their ears or shake their heads repeatedly is irritation within the ear canal. Causes of irritation within the ear canal include bacterial or fungal infection (otitis externa), parasites (mites, ticks, etc.), and foreign materials (e.g. grass seeds).

How are aural hematomas treated?

There are two basic treatment options:

Conservative therapy

-the veterinarian inserts a needle into the hematoma and draws out the fluid; cortisone may then be injected into the hematoma
-the pinna is bandaged to the dog's head for a few days
-the success rate for this approach is only about 50%

Surgery

-the veterinarian makes an incision over the hematoma to remove the blood/serum and any blood clots
-depending on the size of the hematoma, the veterinarian makes either one large incision over the hematoma, or a small incision at each end
-a rubber or latex drainage tube is passed through the hematoma to allow drainage of any fluid that may continue to leak from the damaged vessels
-the drainage tube is sutured to the ear
-the skin that has been separated from the underlying cartilage is sutured to close the space created by the hematoma
-this part of the procedure involves placing several sutures through the pinna to "tack down" the separated skin; it is necessary to prevent refilling of the hematoma
-the pinna is bandaged to the dog's head to prevent further damage

The incision, sutures, and drainage tube can cause the dog to shake its head, so it is important that the pinna be stabilized if it is to heal. In either case, it is also important to identify and treat the cause of the head shaking or ear scratching. Treatment may involve ear cleaning, medication, and removal of any foreign material from the ear canal. If ear drops are dispensed for you to give at home, your veterinarian will show you how to get the medication into the dog's ear.

What can I expect after surgery?

You'll probably be asked to bring the dog back to the hospital for removal of the bandage and drainage tube in 3 to 5 days. The holes in the skin should close a few days later. If there is any discharge from the skin incisions, gently wipe it clean with dilute disinfectant. If the sutures that were placed in the pinna were not dissolving sutures, you'll also need to bring the dog back after surgery to have the sutures removed. This is also a good time for your veterinarian to be sure the irritation in the ear canal has resolved.

by William M. Fraser, D.V.M.

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