Horse coughing while trotting or running

What does it mean when a horse coughs while trotting or running? I have noticed this for about three days. He coughs about 3 times then he's okay. He has no symptoms of a cold and no fever. The vet was out this week and gave him his shots. It started after that. I have been told he is just clearing his lungs. Anyone else know what it might be?

Thanks

I find that a lot of older horses have to cough and clear out their old folk lungs. It also happens when the area you ride in kicks up a lot of dust.

Is your horse coughing or snorting? Snorting is a physiological sign that he is using his body properly, so snorting is good. =]

My horse typically coughs about three times when we first start trotting, more so in the summer when my pasture is dry than the winter. When I start riding, we take a few laps at a loose rein, and then I gather her up and ask her to carry herself through walk to halt transitions, side-steps, leg yields, haunches in, and shoulder in. Then we start trotting and she almost always give a cough or two, and then she's fine. I was thinking it was because of the way we warmed up, so I skipped the "collecting" part of our warm up and went from loose rein walk to loose rein trot and she didn't cough at all. So I went back, did my warm up, and when I asked her trot, she coughed.

I wouldn't be too concerned.

Thanks. Yeah, its only in the trott or canter. We just got into fall in FL so its still between the 80's and 90's. Its funny that he has never done this before though. I just started noticing it this week. After I hear the cough I just let him walk so I don't know if it's every time we speed up or not. Ill have to find out next time.

Coughing can also be due to allergies from dust in the soil or hay. My friend's horse will cough if his hay isn't watered down

It's entirely possible. But wouldn't that mean he should be coughing all the time? Not just when they start trotting?