The past three or four times I've ridden Jazz, he has started coughing when we begin trotting. It's only at the beginning of our ride, during the warm-up...he'll cough four or five times, and then trot on like nothing's wrong. He hasn't seemed odd in any other way, but since it's happened a few times now, it's starting to concern me. Any ideas what might be causing this?
Thanks so much.