Fluid filled ear flap in a dog

Question
Earlier this year our 8.5 year old mixed breed (coon hound/rotweiler)developed a fluid filled sac about the size of a half dollar on his ear flap. We figured our dogs were playing and Bart received trauma to the ear. We watched it for a few days and it slowly decreased in size and went away. Now, he has developed the condition again. Except it is a little bigger and closer to the ear canal. There is no discharge, smell, or redness. The swelling appears to be coming from the tissue between the two layers of skin. We have scheduled an appointment with our veterinarian, but would like to know what we might be dealing with first. Thank you for your time, Raymona

Answer
This is called an aural hamatoma.  As you described, it is a blood filled sac between the cartilage of the ear and the skin.  These result from the dog shaking the head and the ear flap violently enough to cause the blood vessel to rupture.  Sometimes it is from trauma, but usually there is some type of ear infection causing the pain or discomfort.

It requires surgical drainage and fixation.  I open these up by making holes inthe flap with my laser.  Then I remove all of the blood clots, and suture them closed in a way to allow the fluid to drain out rather than accumulate.  It takes 2-3 weeks for healing, but when it is healed, the layers are scarred back together so that it will not re-occur.  Without surgical correction, the ear can crinkle when the scar tuissue contracts or as in your dog's case, it can refill with blood.