What is it about grass that makes a dog's upset stomach feel better?

[Timeforround2]

So occasionally my dog gets an upset stomach and throws up. It's usually after he manages to find and eat something he shouldn't(he's a beagle so he has a knack for finding things)
Anyway this is never really a big deal because I can just give him some pepcid and he's fine again.
However tonight he started doing this inhaled gagging which at first I thought was a reverse sneeze. Then he started frantically dancing by the door and whining so I got up and let him out only instead of going to the bathroom he began voraciously eating the grass. It was insane. I've never seen a dog eat so much grass so quickly. I ran out to grab him so I could bring him in to administer the pepcid but he just started darting every which way, snatching mouthfuls of grass as he went. Since I couldn't catch him and he wouldn't listen (which is odd for him, he's very well behaved) I gave up and let him eat the grass.

He's fine now. He ate the grass, threw up, seemed to feel better then came inside and I gave him the pepcid so now he's sleeping comfortable.
Anyway I was just curious what is it about grass that makes a dog want to eat it when their stomach is upset?
As I explained in my post I know they eat grass when they have an upset stomach.

I want to know what is it about grass that alleviates the discomfort? Is it the sheer fact that grass makes them throw up and in turn that makes them feel better or is there some chemical component in grass that makes them feel better?

 

[Ashleigh]

I've found that usually when my dogs eat grass it is because they have an upset stomach and the grass helps them throw up, getting rid of any bugs or what upset their stomach. Though they don't usually start running around like how you described so it may be different, thats just what I've observed my dogs doing.