Have you noticed horses that are not rugged, left out in the paddock and not given much extra food in winter, get as fluffy as anything, yet in summer they have a beautiful shiny coat??????????
What are us idiots doing,
we buy expesive rugs, feed them expensive food, trying to get the same result.....ha!!!!!!
Maybe we all need to learn something from this.........lo
Try a cool coat, dooner/woolen rug and 1 or 2 winter rug...make sure they cover part of his face as well....(don't over heat him tho) he is still going to get some what of a winter coat..... unless stabled or clipped.
You could also try some linseed in his feed as well, brings out the shine and darker colour. (made sure you boil the linseed first, as it is toxic to horses, unboiled.