I know that chocolate is bad for dogs, but is there a difference between the harm in dark chocolate versus milk chocolate?

Chocolate contains theobromine, a stimulant similar to caffeine. Dogs can’t metabolize theobromine as quickly as humans so the effects of this stimulant are compounded. Baker’s chocolate is often used in holiday baking and is the most toxic form of chocolate because of the high levels of theobromine. Milk chocolate has much lower amounts, but it is certainly best to keep your dog or cat from eating any chocolate at all. If your dog or cat eats a chocolate chip or a Hershey’s kiss, it is unlikely that trouble will result. However, it is a good idea to contact your veterinarian if you are unsure how much your pet consumed or you know that it was a significant amount.