From WebMD:
Last year, there were more than 100,000 cases of pet poisoning in the U.S. Many of these were caused by household substances that may seem perfectly harmless to you. But just because something is safe for people doesn't mean it won’t hurt beloved pets. Some of the most dangerous dog poisons are foods and medications we take on a daily basis..
Full Article: http://pets.webmd.com/dogs/guide/top-10-dog-poisons