For pets, “death by chocolate” isn’t a delicious life goal; it’s a serious concern. Chocolate contains theobromine, which is toxic to both cats and dogs. The darker the chocolate, the higher the amount of theobromine (so milk chocolate is less toxic than dark chocolate), but you should keep all chocolate products out of reach. Depending on how much and what kind of chocolate a pet eats, intoxication can cause vomiting, upset stomach, fever, seizures, and death.