According to the American Society for the Prevention of Cruelty to Animals, although the high amounts of fat and sugar in chocolate are not good for dogs, an even greater concern is the fact that chocolate contains caffeine-like stimulants known as methylxanthines. If ingested by dogs in significant amounts, these stimulants can produce problems such as vomiting, diarrhea, panting, excessive thirst and urination, hyperactivity, abnormal heart rhythm, tremors, seizures, and death.
Typically, the darker the chocolate, the more harmful it will be, with baking chocolate having the highest amount of methylxanthines.
Even though a dog might eat a small amount of chocolate without a reaction, he could also have a severe reaction or suffer long-term damage. It's best to make sure he doesn't eat chocolate at all.
For more information, visit the ASPCA Animal Poison Control Center at www.aspca.org.
