Chocolate contains theobromine (a compound similar to caffeine) which is poisonous to dogs. A dose of 50 mg/lb can be fatal to a dog. Milk chocolate contains 45 mg of theobromine per ounce and unsweetened baking chocolate contains 400 mg per ounce. Just one ounce of unsweetened baking chocolate can kill a small breed dog. Theobromine when ingested by dogs causes release of epinephrine (adrenaline) which causes the heart to race and serious cardiac arrhythmias to develop. Signs of chocolate poisoning in dogs include vomiting, diarrhea, excessive urination, hyperactivity followed by depression and coma, seizures, and death.