One of my Peruvian Paso mares had a 70 lb impaction removed (the vets had
to flush it out by running water thru an incision in the colon, then
massaging the mass to break it up). She apparently hadn't been drinking
for the previous week, because, unknown to me, she wasn't using the
automatic waterer -- she had depended on the other horses always leaving
some water in the bowl and when they were taken out of the paddock, she was
out of luck. She wouldn't drink post-surgery -- I spend a fortune on IV
Ringer's solution -- until I realized she missed her herd. So I brought
her favorite buddy over, she whinnied, and started drinking out of the
bucket the vet had hung in her stall! Her recovery was uneventful, and
while she hasn't done endurance, she has done NATRC, and just had a lovely
colt. Of course she always has water in tubs or buckets now.
About all I can think of, assuming your mare isn't objecting to some
residual plastic odor on her buckets, is that she is depressed about
something. Is she used to being in a stall? Was she out with buddies
before? What did you change just before she stopped drinking? At 15 she
is pretty set in her ways -- you just need to find out what they are and
then go with the flow. And horses can get quietly stressed: my favorite
gelding had to endure 3 months of restrained stall rest while a broken leg
healed -- and now he'll seem mellow if I put him in a stall -- but he'll
have a spasmodic colic if I leave him there for more than a few days!
-- Lynn K. (Santa Ynez, CA)
http://www.silcom.com/~lkinsky