Pad for Sport Saddle

[Kathy Crothers <KC85124@UAFSYSB.UARK.EDU>]

I'm using the "relief pad" from Enduring Designs with my sport saddle and it
really seems to work for my endurance horse.  I used it last fall on my young
horse and didn't lose any points for backsoreness on a two day NATRC ride.
However, when his winter coat came in he had large white spots behind his
withers these weren't solid but more of a roaning.  I haven't a clue as to the
cause since I thought the saddle fit him and never got any dry spots or
palpated any soreness on his back.
Does anyone know if it is possible for the white hairs to have been caused from
a bad saddle fit before I got him last May?  I've tried a few other saddles on
him but the sport saddle still seems to work the best for both of us.  No white
hairs at all on my older gelding and I know I've made his back pretty sore with
bad fitting saddles in the past.  It just doesn't make any sense to me.  Do bay
horses get white hair easier than chestnut?  Before I got the relief pad I used
an equilizer pad but had cut it down some so I didn't have so much bulk under
my legs.  Thanks in advance for the info.  I now have an express lite for sale
and am looking for a used SR saddle.  See the classified on ridecamp for
details.  Happy Trails,  Kathy