Toxic food for dogs Onions, garlic and chives. The onion family, whether dry, raw or cooked, is particularly toxic to dogs and can cause gastrointestinal irritation and red blood cell damage. ... Chocolate. ... Macadamia nuts. ... Corn on the cob. ... Avocado. ... Artificial sweetener (Xylitol) ... Alcohol. ... Cooked bones. More items...