My daughter had a new colt she bought and was told they would go away on ther own, the colt was a weenling, she couldn't take it to the fair because it was a virus. While she wasn't happy with the vet. I told her we would wait until the next year. At that time the colt was a yearling and one day we walked out to the pasture, and they were gone!! Just like the vet said they would be.
He told us no one knows what, or why, they affect colts just that they do, and ther is nothing they can do just wait until they turn 1 and they will go away. Cindy