A Viovet customer wrote:
Our 5 year old doberman has a bubble like swelling on her right ear, we did drain it with a sterile syringe and the fluid was like water with a reddish tinge to it.
Its not causing her any pain to touch but it drops down.
I would not advise you treat these yourself because it is possible to make them worse. Almost certainly this is an aural haematoma. They are common in dogs and cats. They are not infected so antibiotics will not treat them. However once you have drained the haematoma, you have potentially introduced infection so antibiotic cover could be justified.
These swellings have a peculiar cause, which is a sort of inflammatory response. The modern veterinary treatment is usually to drain the fluid and then instil a small amount of steroid afterwards. This can dramatically reduce the production of any more fluid. Sometimes this needs to be done more than once, but eventually they usually settle. Older treatments involved general anaesthetic and stitching the two sides of the ear together, eliminating the possibility of filling up again.
Small haematomas do not require treatment. Even large ones will eventually all absorb away and settle down themselves. However, the bigger they are, the more inclined they are to scar. Scarring in this situation causes the ear to shrink down on itself, producing a slightly crumpled, cauliflower-ear effect. This causes no real problem, but does affect the appearance of the ear. This might well affect your dog to some extent now, whatever you do.
Ideally you should go to your vet. It will probably be drained again and steroid introduced, but it would be up to your vet to decide what to do.