What could be causing this?

[Ziggy_]

I've noticed a few white hairs on my mare's flanks. Its not a solid patch of white, its an area about an inch square and I'd say roughly 50% of the hairs in this area have gone white, the rest are still orange. It looks like hair that grows back white after an injury, although she's never had an injury in that place.

I've drawn a black circle on the pic below to illustrate where the mark is (although its an old pic so you won't be able to see the white) - there's one in the exactly the same place on her other flank as well. What on earth could be causing it?

 

[herewego]

Hi, Ziggy, dont think you need to worry about the white patches. I have a chestnut and as he has got older, ( 10 now ) he has developed little white patchs too. I have looked back into his breeding and his great grand ma was a grey, so maybe thats got something todo with it, who knows. Hey look at Toytown, he has white patches too. Hope this helps
Lahaki

 

[cronkmooar]

Yep have to agree with this - its probably age related - mine is now 22 and has them on his bum, sides of withers and a few on the belly - seems to be more noticable in the summer coat

 

[Box_Of_Frogs]

Sometimes it's a rug, especially if it's in an identical place both sides. Have a good look at all your rugs at the place on the rug that matches the patches on your ned. Check for rough stitches, places where the leg straps attach, etc etc.