> I'd like to hear some rumbling interpretations too!  Like, sometimes 
> when we are trotting and I hear what sounds like a partially inflated 
> tire from his gut.  Is that just an empty sack or what?  Know which 
> sound I mean?  I never hear anyone else's horse do that, but my friends 
> say they do.
> 
> His stomach grumbles as soon as he starts eating.  Am I in the clear 
> then?
Here is my own experience/take on gut sounds....
I am not particularly interested in my horses gut sounds.  My horse is a
piggish eater.  If he is not willing to devour everything offered to
him...I am concerned.  If he goes for food with gusto, tthen I am not
concerned.  I don't really care much what his gut sounds like.
I can't say that I have never had any "trouble" with my horse having some
"discomfort" in his gut and seeming a "bit colicky" but I have never had
any trouble as long as he is willing and eager to eat, even if his gut is
dead silent.
So far, all the horses I have ridden in endurance have been voracious
eaters, snatching at every morsal of food that comes even marginally
within distance.  However, I do have a friend who has a horse that is a
finicky eater (but he is at home too), so I would be less concerned if
Robbie were "off his feed" than I would if one of my horses were.
So for me, the short answer is...
I find "eating habits" to be far more indicative of the state of my
horse's gut than I do gut sounds, either quantity or quality.  
kat
Orange County, Calif.