My ride partner and I had the same problem with one of our horses. (We
share.) We tried probiotics in a paste form at vet checks and that seemed
to help (for the next vet check.) I now feed my horses ABC probiotic
supplement a week before the ride, the paste during the ride, and the
supplement again for a week after. May be overkill, but it has helped a
lot. The problem horse got all A's in gut sounds on my last 50 this year
after a season of C's for gut sounds. I have noticed that poor gut sounds
seems to be common, especially at the first vet check. They calm down
after a while and maybe loosen up inside during the course of the ride.
There is a T-Touch called the belly lift that was shown in last month's
Trailblazer that is supposed to help. I have not tried that.
Good luck. Joyce