Okay, I don't know if this is just me, but I am hearing weird sounds coming from *some of the geldings I have worked with. (*Some as in only the younger ones between the ages of 1-4. I didn't hear the sounds form older geldings, but I don't know if age had anything to do with it.) I hear these sounds when they are trotting and/ or cantering. It sounds like it might be coming from their bellies or somewhere in that area, not from their mouths. I have no clue how to describe the noise besides the fact that it is not high pitched, it has a rythm, and it kind of but not really sounds like a croaking frog. I have never heard this noise from a mare, and I have never been around a stallion, so I don't know if this is a male horse thing or not.