I have a 17 year old Quarter Horse mare that has some sort of eye infection. I have tried two tubes of antibiotic ointment the vet gave me and it didn't work. My vet came out and tried to get a look but couldn't see anything. He wants to come out and put her to sleep so he can go in and check it out good. He say's she may have a sliver in it. I am worried about the putting to sleep part. Any suggestions?? Thanks.