I have noticed that my gelding seems to have a little more discharge from his nose lately. Not alot and basically clear. Just something I noticed and am watching and it actually seems to be a bit less however tonight when I took him out and lunged him when we first got going he coughed 2 or 3 times and a little sorta foamy white stuff came out??? I have never heard him cough before though. And after that he didnt cough again.....and I rode him and we trotted and loped. I am wondering what might of caused this and if I should be concerned? He is in a very large paddock and a stall but it is very dry and dusty right now as the rains have stopped and it is hot. He gets turned out to pasture but not every day. The round pen we work in is also very dusty as well....could dust be a culprit? Any info greatly appreciated...thank you!