I have a 2 yo qh filly. She's always been dark bay. A few months ago I noticed a few white hairs along her topline. Over the last few months they have developed into white spots of hair. On top of that there are single white hairs popping up all over her.
She's never had any sores or anything there where the hair would grow back white so im confuzzled lol
Could be that, how old is she and have you seen her parents, my gelding changed color for a long time until he reached chocolate colored bay. I've had him since he was 5 mnths., and I really hope that my wife's filly stays blue (pictured below)