Allergic to MSM?

I've had horses for years and never had an incident until now. I recently put my horse on MSM for joint maintenance. After taking a couple bites of grain he suddenly lowered his head to the ground and opened his mouth letting the grain fall out of his mouth. He didn't spit the grain out, but merely let it fall and began kicking his belly and wanting to lay down and roll.

Thinking it was just a weird one-time deal, I tried it again the next day and he gave me the same reaction. Head down, grain falling out of his mouth, and kicking at his belly wanting to lay down. I know it wasn't the MSM because it's being given to mutliple horses and they are all fine. Just wondered if anyone else has experienced something similar.

Actually it could be the msm, have you given it to him before? A girl at my barn said that one of her horses, a Morgan, can't have it cause he breaks out in hives, I think is what she said. She told me she has to read everything cause she is afraid it will happen again. So I wouldn't completely rule out the Msm although I don't know how common it is to be allergic to that, maybe it's the brand your using? Maybe try a joint supplement that has msm in it instead of pure msm, and see what happens.

Sorry, I meant to say that I don't think it was a bad batch of MSM because it didn't affect the other horses...

I thought about getting another supplement that has MSM in it. Just nervous he will have a similar reaction. Maybe I should give it a try anyway.

After the episode does he recover pretty quick, or is he down for a while? I think it would be good to know if maybe it's the msm, cause then you would want to avoid buying supplements with that in them.

He recovers within a couple minutes. After about five minutes it's like he never had a problem.