testical problems

We have a 1y 2month old colt but he only has one testical and its small for his age he is out with a mare but still the other isnt coming down and he shows no sign of sallion in him the vet has given him till the end of summer for it to drop if not he will need an op to remove it in case it turns cancerous inside him has any one heard of this before?

Yes, it can happen in all animals, not just horses. We had a dog who never dropped at all. He was dubbed: Cryptorchid, and they had to go in and remove them in surgery. I've seen horse friends, and friends of horse friends have young colts who only drop one, or don't drop at all. It happens from time to time. As long as you have them removed, he should be completely fine. If he does end up needing them removed and you were planning to use him as a breeding stallion, then I am ver sorry. (I was going to breed my dog, and that obviously didn't turn out. Lol. We teased him and called him an "it" for the longest time.)