Just an update, far overdue. I thought I would tell the outcome of our story in case someone else has similar problems, I though this might help. My mare did not stop losing weight, and in August of 2013 we moved barns. Immediately after be de-wormed, she gained weight dramatically. De-worming was included in the board at the old barn, I am guessing someone either forgot to de worm her, or the de-wormer didn't get all of the worms. It could also be the change in grain and hay at the new barn. In any case, she got her weight back up, and was in perfect condition. Sadly, her arthritis worsened, to the point that our vet was skeptical of a life free of pain, so she was euthanized in December. Thanks for reading and I hope this helped someone.
The LORD is my light and salvation- whom shall I fear?