Chocolate contains a caffeine-like alkaloid called theobromine.  The half life in a dog is 17.5 hours.  A toxic dose for a 50 lb. Dog would be roughly 2.2 grams of pure chocolate.  However, the concentration of theobromine varies with the formulation of the chocolate so toxic doses for a 50 lb. Dog are as follows:

• Milk Chocolate50 oz
• Semi-sweet Chocolate15 oz
• Baking Chocolate5 oz

Thus a dog eating 1 oz. Of baking chocolate would have to eat almost 3 oz. Of semi-sweet or 10 oz. Of milk chocolate to get the same dose of theobromine.  The theobromine in candies consisting of chocolate that is coated over some other substance (ex. Filled candies) will be more dilute.

The chocolate in milk chocolate is quite dilute and this is why many dogs can eat a piece and not show toxic effects.  The problem with feeding a dog milk chocolate as a treat is that the dog develops a liking for chocolate. Since dogs do not seem to be as sensitive to bitter tastes as humans, it may then eat the more concentrated and quite toxic baker's chocolate or consume a toxic amount of milk or semi-sweet chocolate if improperly stored.

The treatment recommended in ``Dog Owner's Home Veterinary Handbook" by Delbert Carlson, D.V.M. and James Giffin, MD is as follows:

``If you know your dog has eaten chocolate, induce vomiting by one of the following methods:

1. Syrup of ipecac (one teaspoonful per ten pounds of body weight);
2. Hydrogen peroxide 3% (one to three teaspoonfuls every ten minutes; repeat three times);
3. One half to one teaspoonful of salt, places at the back of the tongue.

If two or more hours have passed, administer activated charcoal to prevent the toxin from becoming absorbed (the above article stated: ``Administration of an activated charcoal slurry is a major component of treatment and needs to be administered by a veterinarian…"). ``