An dog aural hematoma is a localized collection of blood between the skin on the inner side of the ear flap (the "pinna") and the auricular cartilage that contributes to the shape and stiffness of the ear. "Auricular," and "aural," mean pertaining to or coming from the ear.
Causes of Aural Hematomas
Aural hematomas are caused by bleeding from one or more terminal branches of the auricular artery, which provides the blood supply to the ears. The hematoma usually results from trauma to the ear caused by vigorous head-shaking or ear scratching by the dog as a result of pruritus (intense itchiness), which most frequently is associated with an outer ear infection (otitis externa). Other causes of ear irritation, self-trauma and subsequent aural hematomas include atopy, food allergy, flea bite hypersensitivity, parasitic infestation (flea, mite, tick, other) and the presence of foreign bodies that are lodged in the ear canal. Trauma to the ear from some external source can also lead to formation of an aural hematoma.
Trauma to the ear leads to inflammation and break-down of the auricular cartilage and rupture of the fragile superficial blood vessels in the ear flap. As blood leaks out, it becomes trapped between the skin and the ear cartilage, causing the focal swelling known as an aural hematoma.
Prevention of Aural Hematomas
The best and most realistic way to prevent aural hematomas is to prevent the itchiness or other discomfort that causes a dog to shake its head or scratch its ears vigorously. This includes eliminating any parasitic infestation, treating and resolving any ear infection, identifying and resolving food or other allergies and removing any inciting foreign bodies.
Aural hematomas are among the most commonly treated surgical conditions in domestic dogs.
Most localized swellings on the inside of the ear flaps (pinnae) are hematomas, although abscesses can also occur on the pinnae, especially after a dog fight.
Symptoms of Aural Hematomas
Owners of dogs with aural hematomas may notice one or more of the following signs:
Soft, fluid-filled swelling on the inner surface of the ear flap
Head-shaking (repeated, vigorous)
Ear-scratching (repeated, vigorous)
Painful ear when touched
Dogs at Increased Risk
Dogs with particularly pendulous pinnae (long, heavy ears) tend to have an increased risk of developing aural hematomas. Dogs with outer ear infections (otitis externa) or middle ear infections (otitis media), and those with parasite infestation, are predisposed to developing this condition. Dogs living in hot, humid climates, and those that swim frequently, also at are increased risk of developing aural hematomas.
Aural hematomas are not particularly difficult to diagnose. However, they must be distinguished from an abscess, seroma or soft tissue neoplasia (cancer) for an appropriate treatment protocol to be determined. The diagnostic process really is focused on identifying the reason for the dog's head-shaking and/or ear-scratching; the hematoma itself can be identified visually and by taking a fine needle aspirate to confirm that the fluid in the pocket is blood.
How Aural Hematomas are Diagnosed
When presented with a dog that has a localized swelling on the inner aspect of the ear flap, most veterinarians will perform routine blood work – including a complete blood count and a serum biochemistry profile – and submit a urine sample for a urinalysis. If the only medical problem is an aural hematoma, the results of those tests will be unremarkable. Of course, a thorough history will be taken, with particular emphasis on any recent trauma to the dog's head.
The next step is to conduct a thorough examination of the ears, which often requires administration of heavy sedation or even general anesthesia. This is called an "otic examination." The veterinarian will be looking for signs of inflammation and/or infection in the ear canal, which might be causing the dog discomfort and be the reason for its head-shaking and ear-scratching behaviors. She will also look for evidence of parasitic infection and for foreign bodies, such as grass awns, lodged in the ear canal. Blood samples may be submitted to assess thyroid function, and food trials or skin tests can be performed to identify food or other allergies that may be contributing to the dog's condition. Advanced testing may include computed tomography (CT scan) or skull radiographs (X-rays), to assess whether a middle or inner-ear infection is present.
The hematoma itself is quite easy for a veterinarian to diagnose. It is more difficult to track down the underlying cause of the trauma that led to the focal accumulation of blood.
The goals of treating aural hematomas are to drain the blood-filled pocket, facilitate ongoing drainage until the inner layers of the ear flap can re-connect, promote adhesion of the epithelium and cartilage by promoting direct skin-to-cartilage contact, and prevent or at least minimize ear deformity and scarring.
The most definitive way to treat an aural hematoma is to drain it surgically, flush the incision site thoroughly with sterile saline and then place several mattress sutures to bring the affected tissue layers into direct contact and eliminate the pocket that formerly was filled with blood. The success rate of this surgery may be improved if the veterinarian also places a temporary drain, to allow for continuous drainage as necessary for the wound to heal. Glucocorticoid drugs can be injected into the pocket to minimize inflammation and promote healing. A short course of oral anti-inflammatory glucocorticoids is often added to the post-operative treatment protocol. Some veterinarians may opt to only insert a self-retaining drain into the hematoma. This will allow the fluid to drain and can promote controlled scar formation. Whichever technique is used, the affected ear should be bandaged close to the dog's head to prevent further damage and to allow adhesion of the tissues inside the ear flap to occur. This typically takes 2 to 3 weeks, at a minimum.
Draining the hematoma simply by aspirating the blood through a needle and syringe is rarely effective in the long run.
Left untreated, aural hematomas can cause scarring and deformity of the affected ear, sometimes referred to as "cauliflower ear." Of course, surgical correction will only be successful if the underlying cause of trauma to the ear is identified and eliminated. Without alleviating the dog's itchiness and discomfort, self-trauma will recur, as will the hematoma. With appropriate surgical treatment and proper immobilization of the ear to allow tissue adhesion and healing to occur, the prognosis for full recovery without recurrence is good to excellent.