Cocoa within chocolate contains theobromine, a chemical stimulant that, together with caffeine and theophylline, belongs to the group of methylxanthine alkaloids. Dogs are unable to metabolize theobromine effectively. If they eat chocolate, the theobromine can remain in their bloodstreams for days, and dogs may experience fast heart rate, severe diarrhea, epileptic seizures, heart attacks, internal bleeding, and eventually death. One ounce (oz) of milk chocolate contains 44 - 55 milligrams (mg) of theobromine, and baker's chocolate contains 393 mg of theobromine. The lethal dose for 50% of dogs (LD50) is 100 – 200 mg per kilogram (kg) of body weight, yet some dogs will exhibit signs of toxicosis after ingesting as little as 20 mg per kg. In case of accidental intake of chocolate, especially involving a smaller dog, contact a veterinarian or animal poison control immediately; it is commonly recommended to induce vomiting within two hours of ingestion. Treatment protocol also includes intravenous fluid therapy and/or administration of activated charcoal. Large breeds are less susceptible to chocolate poisoning, but can still die after eating four ounces of chocolate.