Onions and chives
Onions are a huge no-no when it comes to cats and dogs. "No matter what form they’re in (dry, raw, cooked, powder, or within other foods), onions are some of the absolute worst foods you could possibly give your pup (it’s poisonous for dogs, and it’s even worse for cats)," says Sadie Cornelius, Marketing Director for Canine Journal. N-propyl disulfide, a compound in onions, is what causes all of the damage. "The toxin causes oxidative damage to your dog's red blood cells by attaching to the oxygen molecules in your dog's red blood cells," says the American Kennel Club. "This reduces the ability of the red blood cells to carry oxygen, and also tricks your dog's body into thinking that the blood cell is an invader." The same goes for cats. Your safest bet? Skip the onion altogether.