I work at a stable with about 25 horses give or take. Its great there, I love it. When I was first told I had Celiac, I panicked about feeding the horses, but even with all the dust from the silo pouring out the grain, the most I get is a headache if the dust is overwhelming on days when the silo is ready to be filled.
I've been on the gluten free diet since May of 07, that first summer at the barn was mostly, "is this okay, is this safe," and so on but at the moment everything is under control. And since I'm terrified of heights I never have to go into the hay loft. The wash stall is my best friend sometimes.
When it comes to showing or being at the barn in general, I pack my own food and bring a cooler along with my tack and everything else.