Several human foods are bad and toxic to dogs. For example, chocolate contains theobromine and caffeine, which can lead to symptoms ranging from vomiting and diarrhea to seizures and even death in severe cases. Grapes and raisins are known to cause kidney failure in dogs, while onions and garlic can lead to damage to red blood cells, potentially causing anemia. Avocados, specifically the pit and skin, contain a substance called persin that’s toxic to dogs. Xylitol, as we’ve mentioned is an artificial sweetener found in many sugar-free products that can cause rapid insulin release and lead to hypoglycemia and liver damage.