Caffeine in pets is toxic to the nervous system and the heart. It is found in coffee, tea, sodas and chocolate. Chocolate is the most well known on the list of what not to feed dogs, and caffeine is one reason. Caffeine is deadly to a dog when the dosage is 180 mg per kilogram (body weight of animal). A teaspoon of coffee contains around 60 mg of caffeine, which means for every 3kg, 8 teaspoons of coffee is lethal. A small dog or puppy would be mostly susceptible to caffeine poisoning. Chocolate also contains theobromine, which is a natural chemical found in cocoa and is also poisonous to dogs. Dark chocolate is worse for dogs than milk chocolate, but all chocolates should be avoided.