OP, did you try to body clip this horse?? The "shedding" looks funny over the flank and there are chunks of hair along the leg & belly. Hard to see but I think there are blade marks on the ribcage in the last photo.
Clipping can make the hair reflect light differently, but it looks like this horse just has some "ticking" which is just a few random white hairs. Not roaning. Posted via Mobile Device
Yes we did clip her. Her coat was so long and thick it came out horrible looking. But she was soooo hot we had to do it. It took us two hours or more and we didnt even get to her legs it was crazy. It didnt help that she absolutly hated getting it done Posted via Mobile Device
Clipping is probably why you're seeing the white hairs now. I've noticed in my paints that their white hair grow longer than the dark hairs during the winter, then the white ticking hairs seem to mostly shed with the winter coat.
Some do show a little more ticking as they age though. Posted via Mobile Device
It is not unusual for them to get scatted white hairs or even small patches that look roan.Most likely sabino gene at work. I had a foal born that had alot of white hairs in her coat,not just in flanks or small spot,but throughout her body she almost looked roanish but wasn't coming from a sorrel & liver chestnut. My one mare now has a couple of roan like areas.She is weird when she sheds as she looks like she is greying or roaning out When she is done shedding no she just her usual bay & white