I actually did induce vomiting in my collie Cody using peroxide one time when he somehow managed to open a drawer while I was away for a few minutes and consume an entire one-pound package of chocolate (M&Ms). I had a syringe type applicator and pumped a couple teaspoons into his cheek every 15 mins until he brought it back up outdoors. I had also called the vet, who said he still probably hadn't had a lethal dose of the chocolate but that the induced vomiting probably prevented him from quite a stomach upset.

Cody was such a Houdini when it came to sniffing out and getting to anything edible. God rest his sweet soul.