Last year at this time my 6 year old horse (Spencer) was breathing real hard after a short trail ride. I noticed it before putting him in the trailer and thought Jeez are you out of shape! When I unloaded him 1/2 hour later he was still puffing...I new something was wrong. It went away after an hour...well, maybe he ate something on the trail and had an allergic reaction. Next day checked on him out in the pasture (hay field with mixed grasses and weeds, lush) and it was happening again. Called the vet. She said they get a lot of calls like this this time of year...some kind of weed goes into bloom and the horse reacts. I took him (and Joey, my other horse) off the lush pasture and put them on a dryer, shorter, plain old grass like front lawn grass. The puffing went away and stayed away. Now it's happening again. But the strange thing is, now BOTH horses are doing it! I just brought them in huffing and puffing, nostrils flaring, sides heaving. I'm thinking it must be an allergy to something in that pasture. But it really seems odd that both horses would have the same allergy. I'm bummed because it's a nice pasture and I hate to pull them off, the other is all cut and ready for the rest rotation. Last year when this happened I had just finished mowing down a bunch of thistles in that pasture and it was so humid I thought that was the culprit. I didn't need to mow this year but I did mow the neiboring pasture this week. Also, last year it was extreme heat and humidity. Right now it is not extreme anything...80's average humidity and dew point. Any thoughts on this? Anyone else have experience with this? Anything I can give to them to help?