I bought a horse about a month ago.  Had a small bump on knee, was told it had been there for 3 years.  He's not been lame or missed a beat since we brought him home.  Had vet check it out 2 weeks ago, she said it was a cyst and unless it got sore, don't worry about it.  Well, he got in a scuffle with my other horse, and now has a scrape on his knee and it's puffy around the bump.  He's still not lame, but I'm worried sick.  Hes a fantastic horse, and I don't want to have him unsound! 

Anyone had something like this?  I am calling the vet in the AM to schedule an X-ray to be on the safe side. 

TIA