For improving your horses coat and physical appearance they need to be healthy on the inside! Here's some supplements that might do the trick for your horse's coat ;)
Biotin Supplements- Biotin supplements have vitamins that help with hoove, mane, tail, and coat health. Also, using MSM will help the body use the Biotin and helps the joints!
Omega Supplements- These help promote healthy skin, shiny coat, earlier shedding, hoof health, and muscle health!
Here's some grooming supplies for a gorgeous physical
Orvus Shampoo: Its great for any really dirty white markings. Pretty much industrial strength and gets the dirt that is really deep down out. It is in a concentrated gel form and you need only to apply a small amount. Let it sit for a few minutes to do its job and then wash thoroughly. This will remove deep-down stains and leave legs perfectly white.
Mayonnaise- It sounds super silly but mayonnaise makes your horses mane clean and shiny and is great for thick manes that tangle easily. Use it like shampoo and then wash it out. It will make your horse's mane as smooth as silk.
MTG- I consider it the best skin product on the market. It smells kinda bad, but it's sooooooo worth it. It soothes itchy skin and gets ride of all kinds of fungus.