Not all chocolate is created equal

A friend called me in a panic. His four-month-old puppy got into a pan of chocolate brownies and ate a couple of big ones before anyone noticed her. Should he be worried? His puppy weighs about 35 pounds and he estimated each brownie to be 5×4 inches by 1 inch high.  

The important question here is, “What kind of brownies were they?” You see, brownie mix itself doesn’t have a very high chocolate content; but adding semi-sweet chips or chunks can raise it to potentially dangerous levels. My friend’s brownies had no added chocolate; so I advised him to watch the pup carefully for increased agitation and to be prepared for a few runny stools in the following days. He called three days later to tell me she was fine.   

So, what do you do if your dog does eat chocolate? Again, it depends on what kind and how much. Theobromine and caffeine, collectively known as methylxanthines, are the chemical compounds responsible for the damage to the heart and nervous system that we associate with chocolate toxicity in dogs. Toxicologists describe toxins based on their LD50, which is the dose of a substance that, when a population is exposed to it, would be expected to be fatal to half that population. The canine LD50 for chocolate is about 100-200 milligrams (mg) of methylxanthines per kilogram (kg) of dog. In US terms, this is 230-460 mg per 5 pounds of dog. But, according to the Merck Veterinary Manual, signs of toxicity have been reported at much lower levels, even as low as 20 mg/kg (45 mg/5lb), in sensitive dogs.   

So, how much of these methylanthines are found in chocolate? Although the actual levels vary among cocoa beans and brands of chocolate, there are some general guidelines: Cocoa powder is the most potent, with about 800 mg per ounce. Unsweetened baking chocolate is next, with about 450 mg/oz. Semi-sweet and sweet dark chocolate have about 150 mg/oz. Milk chocolate has about 64 mg/oz. The amount in white chocolate appears to be medically insignificant. Given these values, just 10 ounces of chocolate chips would have reached the LD50 for my friend’s dog (35 pounds at as little as 230 mg/5 lb). And, since every dog is unique, there’s no way to tell how little would have caused her to be ill.   

If you think your dog may have consumed enough chocolate to be in danger, call your vet or local emergency clinic immediately. The receptionist will likely ask you to bring your dog into the clinic right away so that the vet can assess the pet and decide whether to induce vomiting and give something to deal with any chocolate that may already have passed though the upper digestive tract. If the ingestion was more than two hours previous, or if the dog was already showing signs of toxicity, other treatments would be necessary.   

You might be tempted to induce vomiting at home; but you should do this only if instructed to do so by your vet. You would likely be directed to give either hydrogen peroxide or syrup of ipecac for this purpose. But, hydrogen peroxide has the potential of forming oxygen emboli at high doses. And ipecac, although once a common medicine cabinet item, can be pretty hard to find these days. Since your vet has access to drugs that induce vomiting more effectively than either of these alternatives, it’s probably best to get your dog to a clinic as soon as you can.   

Prevention is far more effective than any treatment when it comes to chocolate toxicity in dogs. So, please keep your chocolate stored safely out of Fido’s reach.