Hey all! First: I do NOT own this horse. I ride him, and do some training. I can NOT have a vet out to scope him, nor will the owner, as he is a pasture pet mainly and this issue isn't at all life-threatening presently.
Ok, I'm going to give a detailed description of the issue. If you could do your best to try and give some help on a possible diagnosis and/or treatment, BASED on the information I have given, that would be lovely. If you are unable to do that, I would ask you to refrain from posting. Thank you!
12yr(?) Appy gelding. Lives outside 24/7 with 6 other horses in good pasture. Has never had any respiratory problems ever up until January or so of this year.
Over the winter we noticed him coughing occasionally. Figured maybe it was the dry air, though none of the other horses ever coughed. Towards spring we still noticed him coughing every so often, so we paid more attention to it. We noticed that some days (NOT everyday, but usually once a week or so at least) he seems to be breathing faster than usual. They're relatively shallow breaths, and fairly quick. He does not strain for air, and does not seem stressed at all.
Also, if it is a bad day, he sometimes gets a bit "wheezy" for a few seconds, usually followed by some coughing. These episodes generally follow some sort of trotting or cantering, though not always. If it is a coughing day, he will usually resist going on the bit, even at the walk.
Again, PLEASE note that this does not happen every day, and he is never distressed about it.
My own thoughts:
1) He's about 12yrs old, and the last 6months or so is the first time he's every had the coughing/wheezing/shallow breathing.
2) It isn't every day, more like once a week or so.
3) When it is a coughing day, he will not go on the bit.
4) He doesn't "roar", and he doesn't gasp for breath.
5) Though it sometimes directly follows a trot session, it doesn't always. We can spend three hours cantering around the forest or swimming in the river most days and he is perfectly fine.