Gazette Vet: ’Tis the Season for Chocolate Toxicity

Gazette Vet by John Andersen, DVM

I remember going to a Christmas party years ago at the house of a friend who owned two Labrador retrievers. Late in the evening, most of the guests had filtered to the basement where a band played, leaving the food and the dogs alone upstairs. Feeling the need for a late snack, I wandered upstairs to find both dogs on their hind legs, burying their faces in various chips, dips, and other indulgences on the banquet table. One of the dogs made eye contact with me and immediately ran over to the top of the stairs, growling ferociously. He was essentially saying, “Go back down stairs, silly human. This is our party!” I was not looking to get bit and did as he asked. I could hear him promptly return to his party as I headed back down the stairs to mine.

Just so you don’t think I’m totally irresponsible, I did inform their mom and dad, who were not so intimidated by their pack mentality. Point of the story? If you leave it out, they will find it and eat it. And this time of year, the calls are about to start rolling in about…chocolate!

In the Christmas season filled with candy, cookies, and cake, dogs are going to get into some chocolate! Unfortunately, as you may well know, chocolate is toxic to dogs and can cause some serious harm depending on how much they eat.

There are two reasons why chocolate ingestion will make dogs sick. The first is simply that many chocolate products (like that leftover Halloween candy) contain a lot of fat and sugar. So for a dog who gets an incredibly regimented diet of dog food, then gets a sudden high fat/high sugar snack, it’s not surprising that some good ol’ stomach upset may follow.

The second reason, however, is that chocolate contains theobromine, a naturally occurring compound in cacao seeds, from which chocolate is made. Depending on the dose, theobromine in dogs causes vomiting, diarrhea, hyperactivity, tremors, seizures, and in severe cases, death.

Different types of chocolate, due to the differing amounts of chocolate liquor present, will have different concentrations of theobromine in them. Milk chocolate is the least toxic, containing on average 44mg of theobromine per ounce of chocolate. Semisweet chocolate has more, containing 150mg/ounce, while baking chocolate has the most at 390mg/ounce (almost 10 times more theobromine per ounce than milk chocolate).

Toxic doses of theobromine for dogs are 9mg per pound of dog for mild signs and 18mg per pound for severe signs. So for example, a 70 pound Labrador would have to eat ~30 oz of milk chocolate to have signs of true theobromine toxicity (approx. 19 of the typical Hershey’s milk chocolate bars). But I’m sure that same dog would have some pretty bad things brewing in his belly if he only ate 5 bars! On the other hand, this same dog would only need 3 ounces of baking chocolate to get a toxic dose. Most of the true toxicities we see involve smaller dogs who get into dark chocolate (but we talk to A LOT of clients whose dogs are having significant diarrhea after a less-than-toxic dose.)

So what do you do if your dog gets into some chocolate? First, I would call your vet. We will help you figure out if the dog ate a toxic dose or not and whether your dog is in need of medical treatment, or whether you may just have a dog who needs to be let outside a few times in the middle of the night. If your dog did consume a worrisome amount of chocolate, we may or may not try to make it vomit, depending on when it ate the chocolate. Otherwise, dogs with chocolate toxicity need hospitalization and IV fluids while we wait for the toxic theobromine to leave their system.

Fortunately, most chocolate ingestions in dogs are not serious—although cleaning up dog diarrhea in the living room is pretty serious to some! Just remember that even the sweetest dog is a thief when it comes to sweets! Merry Christmas!