I think its unethical to dye a horse's coat for showing...
I agree with this. I watched a girl dye her boss's black horse because it was sunfaded. The mare was kicking and pawing and trying to bite her sides for the entire 45 minutes she had to have it in - you can't tell me it didn't irritate her skin at all
When my Black bay mare sun fads I buy Quick Black shampoo. It will turn your hands blue, but it dose not bother my mare. It takes several uses to fix the fading but it dose not irradiate (and it helps keep the dust from sticking to her lol). They have that brand for horses of all colors, it puts a UV protection into the coat to protect it against further fading, as well as conditioning it. My mare feels like silk after. I don't show but I hate when she turns into a chocolate bay when she is BLACK lol.
Dying is probably the wrong idea here. Not onlycould you not guarentee the color would be the same but also horses coats are not just one solid color.plusyounever know how your horses skin could react to it.
There ARE however horse shampoo that merely help bring out the natural colors and prevent fading etc.