Most dogs like chocolate, but it can be dangerous. Chocolate contains methylxanthines (made up of caffeine and the alkaloid theobromine). Methylxanthines are not toxic to people in the concentrations found in candy and baked goods, but when ingested by dogs the effects can be lethal. Although some dogs tolerate chocolate far better than others, note that a dog who weighs 5 to 10 pounds (2.3 to 4.5 kg) could die after eating as little as 4 ounces (113 g) of baking chocolate (not candy); a dog who weighs 20 to 40 pounds (9 to 18 kg) after eating as little as 16 ounces (450 g); and a larger dog after eating two pounds (about 1 kg). Dogs have been poisoned by eating an entire pan of brownies or a chocolate cake. Signs of chocolate toxicity occur within hours after the dog ingests the chocolate. They include hyperexcitability, vomiting, frequent urination, diarrhea, rapid breathing, weakness, seizures, and coma. Death, which is rare, occurs by cardiac arrest.
Treatment: If you know your dog has eaten chocolate within the past six hours and he has not already vomited, induce vomiting (see page 25). Record the type and amount of chocolate ingested (sweet and semisweet chocolate in candy bars is not nearly as toxic as baking chocolate). Then call your veterinarian for further instructions.
Prevention: Use commercial dog products as treats. Keep all chocolate stored securely to prevent accidental ingestion. Make sure everyone in your family, especially the children, understands that chocolate is dangerous for dogs.