Horse has Diarrhea!

The horse I lease in the summer (lives in a pasture) came to us two days ago. He's been staying in a large corral with sparse dry grass... not really pasture, because he doesn't want to eat the grass. I've been giving him hay. Last night I introduced him to a little bit of grain (just a little, because he's not really used to it). Then walked him around to get it to settle. This morning he seems fine (perky, begging for treats, happy), but he has terrible diarrhea!! He isn't biting his flank or lying down or anything... it's just liquid!!

I walked him around some more, and his hooves aren't hot or cold. He's walking just fine... but I still hope this won't turn into anything more serious. I'm guessing this is because of the different diet he's been getting...

We have lots of lush grass in our yard? Would it help if I let him eat that?

Is there anything I can do to make this better? Will it turn into colic?? I'm really worried! Please help!

Thanks!

I would think its quite obvious what the problem is, unless he had it before, How much did you give him? Any diet change should be done very very slowly, esp, one that is coming off of, less than desirable pasture. I would watch him , do you have just good quality grass hay to feed? Why did you introduce grain? I would not suggest giving it again, until he can get use to hay alone, if he's hungry he will eat the hay...:) Make sure he has also has clean fresh water daily to make up for what he's loosing.

I didn't give him very much-- maybe 3/4 a cup? Yes, I've got some good quality hay for him. I just put it out... if he gets hungry he'll eat I suppose. Yeah, I don't think he needs grain. He'll have to just deal with hay for the summer. He also has plenty of fresh water and seems hydrated (skin snap back). He seems his usual self, though... So I don't think I have to worry anymore... just keep him from having any more. Thanks soo much!!

Good, and your welcome...I would just keep him on good quality hay, keep it simple is my motto...:)