Hematoma looks like a swollen ear and results from vigorous flopping of long ears back and forth as a dog shakes its head. Hematoma describes a condition of accumulated blood between the cartilage and skin of the earflap. Hematoma is caused by excessive, severe head shaking or scratching at the ears with the back feet.

The most common underlying causes of hematoma are ear infection, ear mites, fleas, or trauma. The head shaking caused blood vessels in the ear to rupture and bleed, causing the swelling. Surgery is required to drain the hematoma and re-attach the cartilage to the skin. Treating the underlying infection is required to allow healing and prevent reoccurrence.