The vet I took him to I'm thinking is pretty clueless when it comes to horses. I can't find a good one around where I live. He didn't do any test just said it looked like a hemotogan (don't know how to spell it). That it should go away in a week or two. He didn't know about the eyes and said that he was probably dehidrated, that's why he was drinking so much water. The horse acts fine, it doesn't seem to be effecting him at all with anything. He still eats good and it doesnt hurt him if you touch or rub on the lump.