Patches, I've got 6 dogs, all of which eat rabbit poop, horse poop, goat poop, anything they can find here on the farm, and the worst that has happened is some bad breath, or maybe a little throw up...
As for stopping her from eating it, say "Aaah! Leave it!" if a firm, yet calm vioce, and keep a close eye on her, when you see her going to get some say "aaah! Leave it!" and if she so much as looks at you say "Ohh good girl! That's a good gril!" love on her, and if you've got treats in your pocket or a toy with you, reward her with more than verbal praise.
Good luck, and welcome to the forum! If you've got more questions, feel free to ask, and I and others will try our best to help you!