I also have a black horse who is not a true black and that is the reason she bleaches out in the hot Texas sun during the summer. Since your horse is a yearling, I would suggest to NOT put a fly sheet with UV protection on him until he is fully grown as you will go thru several during his growing stages. I use the Kool Coat and thoroughly love it. I get a discount from SmartPak for being a member of AQHA. But, until your horse stops growing, other options not mentioned are: Santa Fe coat conditioner with sunscreen. There are other shampoos and bug repellents with sunscreen available.