Animal Health Matters: Pets and Christmas chocolate do not go well together

I think one of the reasons I get excited about Christmastime is the change of pace it represents.

We (most of us, anyway) don’t typically “deck the halls” in May or have a Christmas tree in the living room year-round. The same goes for Christmas treats -- if you’re like our family, you have special cookies and goodies you only see during this time of year.

Those delicious treats are so good, but bad for our waistlines! They’re not good for our dogs and cats, either.

Veterinarians who work with pets observe that the holiday season coincides with a spike in visits from the sick dog or cat that found Aunt Ethel’s stash of cookies and overdid it. Dogs, in particular, have no common sense about stopping when encountering unanticipated feasts.

Chocolate gets a lot of press as a potential toxin for dogs. As a result, I think most people know not to feed dogs chocolate. But others figure how can something that we can eat to our heart’s content be so bad for pets? Good question.

The answer is theobromine. Cocoa beans produce this plant chemical, which becomes part of the cocoa used to make chocolate. Once in our bodies, theobromine acts similar to caffeine (also found in chocolate, by the way). Animals are more sensitive to these compounds than we are.

In high doses, theobromine stimulates the central nervous and cardiovascular systems. An animal eating too much chocolate will first show signs of restlessness, excessive drinking and vomiting, progressing to rapid heart rate, tremors and, in severe cases, seizures. These signs are all due to the stimulant effect of theobromine. In toxic doses, theobromine can kill an animal due to heart failure.

I can already hear it: “But Doc, I give Snookums a piece of chocolate when she’s been a good girl, and she’s never gotten sick.” I don’t doubt it. A common toxicology axiom is, “the dose makes the poison.” The effects of any potential poison depend on how much is consumed.

Not all chocolate is the same regarding theobromine levels. Have you ever tasted baker’s chocolate? Its bitterness indicates higher theobromine levels compared to, say, milk chocolate. In that regard, dark chocolate is more hazardous than milk chocolate.

For example: milk chocolate contains 64 milligrams of theobromine per ounce, while dark chocolate weighs in at 150 milligrams per ounce. This makes dark chocolate about two and a half time times more potent than milk chocolate. Baker’s chocolate is seven times more potent.

Signs of chocolate poisoning in a dog show up when nine milligrams of theobromine per pound of body weight are consumed. At 20 milligrams per pound, the animal will have heart problems and tremors. A fatal dose can be as low as 50 milligrams per pound.

From this, it’s apparent that smaller dogs are at a higher risk for toxicity than larger dogs. My 25-pound Corgi would need to eat 225 milligrams of theobromine before clinical signs occur. This amounts to three and a half ounces of milk chocolate — about two Hershey’s bars or 21 Hershey’s Kisses. For a 75-pound lab, triple that amount. So while eating this much could (and occasionally does) happen, we’re talking a pretty substantial amount of chocolate.

If dark chocolate is on the menu, cut that amount by more than half because of its higher theobromine content.

While theobromine can harm these binging pets, the high fat content of chocolate is perhaps more commonly problematic. Severe or even life-threatening illness due to pancreatitis can occur, showing up as intense abdominal pain, persistent vomiting and diarrhea.

If you discover your pet has helped themselves to a chocolate feast, call your veterinarian. Estimate how much chocolate (and what type — milk or dark) was consumed, along with an idea of your animal’s weight. This will help your vet determine the potential severity of the problem. There is no specific antidote for theobromine poisoning, but medications to counteract nervous system and cardiac problems and fluids to help the body flush out the poison faster can be given.

So, more reasons to reserve goodies strictly for the human inhabitants of your household this holiday season. On behalf of all of us here at South Dakota State University, I hope you and your animals have a great Christmas season!

Russ Daly, DVM, is the Extension veterinarian at South Dakota State University.  He can be reached via e-mail at russell.daly@sdstate.edu or at 605-688-5171.