An ear hematoma is a pocket of blood within the flap of the ear. It is an occasional problem of dogs and cats. It occurs when the blood vessels in the flap of the ear break or become leaky.
There are plenty of theories, but we do not know what causes ear hematomas. Some patients that get hematomas have inflamed, infected ears and some don't; ear infections are a very common problem in dogs and the vast majority of them do not get hematomas. Some patients that get ear hematomas are shaking their heads but most are not. Some patients with ear hematomas have other skin diseases that might predispose them to the problem, but most do not.
There are as many treatment options as there are veterinarians. These options range from doing nothing to medicine to surgery. It is worth considering the pro and cons of a few of these options:
Doing nothing: Eventually the fluid will reabsorb; this may take a week or it may take several months, but it will reabsorb. There might be a slightly greater risk that the ear will crumple (cauliflower ear) as it heals compared with surgery, but this author believes there is not.
Aspirating (removing the contents with a syringe and needle): There is the immediate gratification of flattening the hematoma. Sometimes the blood has clotted or partially clotted and it cannot be aspirated. Aspiration does not eliminate the pocket, and it has a tendancy to fill again immediately. It will ultimately take just as short or long a time to heal as if nothing was done. Introducing infection into the pocket and turning the sterile hematoma into an infected abscess is always a possibility, even with careful technique, and even with placing the patient on antibiotics afterward. If an abscess occurs it has to be treated surgically.
Surgery (many different versions): The hematoma is immediately resolved because the pocket is eliminated, and the chance of it refilling is very slim. Any type of ear hematoma surgery requires general anesthesia, and is somewhat costly. Patients are usually uncomfortable for a week or two afterward, even with proper pain medication, and some of them require bandaging. Some patients heal very well, only to have the hematoma recurr weeks, months, or years later.
A special note about laser therapy: Laser therapy is the application of laser light to body tissues. It promotes healing in a variety of ways. The therapy requires a special laser instrument. It is not painful (human patients typically report it feels good, and many dogs and cats act as though it does) and each session only takes a few minutes. It appears that laser therapy will speed the resolution of ear hematomas for some patients.
This Author's Recommendations
Evaluate each patient with a hematoma individually. Carefully examine and run appropriate diagnostic tests to detect potentially significant ear, skin, or other problems, and treat any problems detected.
Start oral antiinflammatory treatment with low-dose cortisone and high-dose fish oil, unless it is contraindicated to do so for a particular patient.
Consider laser therapy.
Wait. Do not aspirate the hematoma and do not do surgery. It may take weeks to months for the hematoma to reabsorb, but it will. (Surgery can always be reconsidered if the patient is or becomes uncomfortable to the point that it is affecting their quality of life.)