I'm probably misremembering, but does one have to take extra care with spotty horses in the sun, given the fact that they often have pink or pale skin round the muzzles and eyes?
Mine isn't spotty but a grey with a mostly pink muzzle. I've always put the waterproof factor 50 kids stuff on in sunny weather in the morning & before riding, not had sun burn yet in 21 years.
Think mine will pull a very sour face if I come anywhere near his face with the suncream... It will have to be the fly veil / nose net for him, I guess (although I bet I will find it stuck in a tree somewhere!)