Is chocolate toxic to dogs?

Dear Cecil: Many people have tried to convince me chocolate is toxic to dogs. I even heard a news report warning people to keep dogs out of the Halloween candy for that reason. However, my four dogs have stolen chocolate cakes, pies, and candy bars without ill effects. What gives? Jason Eshleman, Berkeley, California

Cecil replies:

Either you’re in serious denial — the mutts, they moved much lately? — or you and they got lucky. Chocolate is the third most common cause of poisoning in dogs. Certain chemicals in chocolate, notably caffeine and theobromine, can cause erratic heartbeat and in large enough doses can kill your pup. While you’re getting used to that idea, consider this: the second most common cause of canine poisoning (after rat and mouse poison) is ibuprofen, the well-known pain reliever. Dogs apparently love the smell and taste, so they chew through the bottles, eat the contents, vomit their guts out, and die. ODing on chocolate and Advil might seem nutty to us, but it’s pretty serious to the dogs.

Sick of chocolate

Dear Cecil:

I was intrigued by your column on chocolate poisoning in dogs, but don’t you think we have an overeating problem here rather than one of poisoning per se? You mention a toxic threshold of two ounces of milk chocolate per kilo of body weight. For my Jenny, who weighs 20 kilos (44 pounds), that’s 40 ounces of chocolate! Let’s put the issue in human terms. I’m a big boy at 100 kilos. If I ate 200 ounces (12.5 pounds) I think I’d get mighty sick, and I don’t think we could blame it on the chocolate.

By the way, what the hell is theobromine and what does it do?

— Roger Strukhoff, via the Internet

You ever watch your dog eat? Dogs will make pigs of themselves if they get unlimited access to a food they like. Vets at the National Animal Poison Control Center say it’s not uncommon for a 10- to 15-pound dog to eat a pound of chocolate, wrappings and all. The bigger breeds, proportionally speaking, are almost as bad.

It’s true that at extreme doses the sheer volume of fatty food can cause problems such as pancreatitis, which is often the culprit when a dog gets sick after eating garbage. But chocolate alone is plenty toxic. This is more apparent in the concentrated forms of chocolate. I cited the toxic threshold for milk chocolate because, being sweet, it’s what dogs gorge on most often. But where milk chocolate contains 65 milligrams of caffeine and theobromine per ounce, semisweet chocolate contains 165 milligrams and baking chocolate has 300 to 400. A dog who eats a package of baking chocolate isn’t necessarily overeating but could still wind up dead.

Theobromine is one of a class of chemical compounds called methylxanthines, which also include caffeine and theophylline (found in tea). They’re all stimulants and not good for your pooch (or for you, for that matter) in excess.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.