Swollen dog ears usually look like they are inflated and cannot heal on their own. This is caused by ear hematoma. The content is not gas, but blood and pus. Generally, ear inflammation, parasitic infection, or allergies can cause dogs to have swollen ears. For ear hematoma, you need to take your dog to a pet hospital for treatment to avoid worsening of the condition. It is also best to choose surgical treatment to reduce the possibility of later recurrence.