hi thanks for responses. my cat doesnt shake head or scratch ear. was told maybe thats what happened in begining when he had ears cleaned .he quit eating his crunchy food since ear cleaning no one seems to know why? he was fine before ear cleaning at vets when he had hi s annual shots. mystery now. thanks
Savas has given you some great answers and the only thing I would add is that you need to find out what the underlying reason is for the head shaking and ear scratching. Hopefully, once you treat the existing hematoma and the underlying problem, you won't see a recurrance.
Tomcat
A hematoma is a collection of blood, fluid or serum in the pinna (ear flap). It's essentially a big blood blister.
Blood vessels in the cartilage of the ear will break and form these clots if a cat is scratching excessively from mites or a similar problem.
There are two ways to correct it; one is to aspirate the fluid out and inject a cortisoidal steroid into the vessel in the hopes it will prevent fluid from reforming. This is the less expensive method of treatment, but it only has a 50% success rate.
The other method is surgical and is much more successful.
If your cat is scratching obsessively, has a swollen area on the ear hat is tender, or is tilting it's head to the side...these are all signs of a possible hematoma.
Untreated, infection tends to form which is, of course, dangerous in itself. While hematomas can resolve on their own, there's a high risk of scarring that will lead to "cauliflower ear".