Why Is Chocolate Toxic to Dogs?

Most people know that chocolate is toxic to dogs but not why. Let's go in-depth on canine chocoholism.


Just about everyone knows that chocolate is toxic to dogs. (For those of you who don’t know: Yes, it is.) But the other day someone asked me why people can eat chocolate without trouble, but when dogs eat chocolate they can die.

Chocolate causes trouble for dogs in two ways. First, it is poisonous to them. Also, the fatty butter, cream, and nougats often present can cause their pancreases to melt down — literally, in some cases.

Chocolate contains two toxins that are closely related. You’re familiar with caffeine, and most of us are familiar with theobromine, which is what gives human chocoholics the famous chocolate high.

Dogs are much more sensitive to these two agents. But sensitivity is not the only factor at play here. Canine chocoholics consume, on average, far more of the stuff than even the most ardent human might. In fact, dogs will generally consume just about any quantity of chocolate they can find (did I mention that dogs really love chocolate?). I have met many a Beagle who has eaten two pounds of dark chocolate bars. That’s the equivalent of you eating eight to ten pounds.

What happens if my dog eats some chocolate?

To understand why dogs get in trouble, imagine you’re especially sensitive to caffeine and theobromine (I’m talking about the sort of person who is up all night if he drinks a cup of coffee after noon). Now picture eating 10 pounds of dark chocolate. What might happen?

Everyone who drinks coffee in the morning knows that caffeine stimulates the gastrointestinal tract. It keeps the trains running, so to speak. An overdose of caffeine (and the closely related theobromine) would have the trains running out of control. Diarrhea is a common symptom of chocolate toxicity in dogs.

If you’ve ever had too much coffee, you’ve probably felt jittery and felt like your heart was racing. Our imaginary human chocolate-overdoser is likely to feel the same way. But chocolate consumption may make your dog’s situation even worse. Dogs don’t just get jittery; they can develop full-blown psychosis and seizures. They also can go into comas. And dogs’ hearts develop full-blown arrhythmias, which can lead to cardiac arrest.

Going back to our imaginary person who has eaten 10 pounds of dark chocolate — I’d be willing to wager you’d have a world-class bellyache. You’d also be unbelievably thirsty, since chocolate stimulates thirst.

Canine chocoholics frequently binge on water after their indiscretions, and all that fatty goodness (the butter, cream, nougat, and so forth) can overwhelm the pancreas, which helps to digest food. This can lead to pancreatitis, in which the pancreas begins to digest itself. Severe cases can be life-threatening. Even less severe ones may predispose dogs to diabetes later in life.

So that’s the bad news. Now for the good news. In more than 12 years of treating dogs for chocolate ingestion, I have yet to lose a patient. And I should point out that I have worked as an emergency clinician for the last five years, so I see far more than my fair share of canine chocoholics.

How is this possible? First, when it comes to toxicity, not all chocolates are created equal.

The darker the chocolate, the more caffeine and theobromine it contains. White chocolate and milk chocolate aren’t terribly toxic; my pal Buster (who weighs 60 pounds) once ate a pound of See’s Candies with no adverse effects whatsoever, other than the loss of the candy.

Next, not every chocolate-consuming dog is a 30-pound Beagle eating two pounds of dark chocolate. Chocolate toxicity depends very heavily on the dose consumed relative to the size of the dog. A lethal dose in a Chihuahua won’t touch a Great Dane.

Also, I am happy to report that most dogs have relatively resilient pancreases. As I mentioned, that pound of See’s Candies didn’t affect Buster’s pancreas at all.

Finally, chocolate toxicity is treatable. Chocolate is sticky, and it draws fluid into the stomach. Making your dog throw up usually gets most of the toxins out, which also makes treating chocolate ingestion very satisfying for veterinarians.

I remember one chocolate Lab who consumed several pounds’ worth. I called him the Double Chocolate Lab until I got him to vomit, at which point he became the Chocolate Volcano. He went on to enjoy many other adventures in life.

Intravenous fluids help to eliminate the toxins from the bloodstream of canine chocoholics, and most of the symptoms can be controlled most of the time by veterinarians. As I said: I have yet to lose a patient to chocolate ingestion.

What should you do if your dog breaks into your chocolate stash?

First, consult a chocolate toxicity calculator to determine whether you need to do anything at all. I like this National Geographic calculator (which shows that an 11-pound Pug would need to consume 487 ounces of white chocolate, or nearly three times its own weight, to be at risk of death). You can also call your vet or the ASPCA’s Animal Poison Control Center.

I do not recommend trying to treat your dog in any way at home, especially in Pugs, Bulldogs, Boston Terriers, Pekingese, and other short-snouted breeds. The old hydrogen-peroxide trick for inducing vomiting often doesn’t work, because the dog’s stomach will be too full of fluid for it to be effective, and the peroxide can cause esophagus and stomach ulcers. All dogs, but especially short-snouted ones, are at risk of inhaling vomit. Get your dog to the vet straight away.

Finally, be sure to talk to your vet about the treatment plan. If you own a French Bulldog, ask about the safety of making him vomit. And if your dog has consumed a less-than-lethal amount, be sure to ask whether giving him charcoal is necessary. Charcoal is often used to absorb chocolate toxins, but in my experience, the treatment can be more dangerous than the chocolate.

Charcoal can cause life-threatening changes in blood salts (hypernatremia, to be exact). Tragically, I have seen one dog die from charcoal treatment, and have seen another dog come very close. (I was not the vet who administered the charcoal to either dog; I reserve charcoal for only the most severe cases.)

The take-home message is simple. Chocolate is toxic to dogs, but chocolate ingestion is not always a catastrophe. Exercise caution and common sense, and don’t try to treat at home.

And above all, save the chocolate for yourself.

Got a question for Dr. Barchas? Ask our vet in the comments below and you might be featured in an upcoming column.

(Note that if you have an emergency situation, please see your own vet immediately!)

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1 thought on “Why Is Chocolate Toxic to Dogs?”

  1. how about chocolate covered snails? can dogs be safe with that as a gourmet treat? ‘sit boy, sit…gimmee paw’…. GOOD BOY!!!!

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