The flesh of apples is not dangerous, but a compound called amygdalin can make the seeds poisonous.
Garlic can kill dogs because it contains thiosulfate, a chemical that hurts red blood cells. It takes a lot of garlic to make a dog sick, but some kinds are more sensitive than others.
Even though milk and dairy products can help increase calcium levels, they can be bad for dogs and make them less able to handle lactose.
Macadamia nuts are the worst kind of nut for dogs to eat. These are the most dangerous, because they can make you throw up, feel weak, get too hot, or stop your body from working.
Small amounts of mustard won't kill a dog, but bigger amounts can be dangerous. Because mustard is only mildly poisonous, vets often suggest it as a way to make an animal throw up when they need to.
Theobromine, a stimulant found in chocolate, is deadly to dogs. How much theobromine is in chocolate varies on what kind of chocolate it is.
Due to the thiosulfate they contain, onions can be dangerous for dogs to eat. Some dog breeds are more sensitive than others, and the size of the dog makes a big difference.
Giving your dog a raw, fresh bone to chew on is great, but cooked bones should be avoided. These are easy to break, and a lot of them can cause constipation or a hole in the intestines, which can be deadly.