Gazette Vet: Cocoa No-No


By John Andersen, DVM

Each year from Halloween through Christmas, many of our homes become filled with chocolate and sweets. Unfortunately, dogs will be dogs and when they find your stash of chocolates, they can become seriously sick.

Chocolate contains theobromine and caffeine, which are both types of compounds called methylxanthines. Unfortunately dogs are very sensitive to methylxanthines, and they love chocolate. This is a recipe for disaster that we see all too often this time of year.

Methylxanthine toxicity in dogs looks a lot like what you would think a caffeine overdose would look like – hyperactivity, vomiting and diarrhea, increased heart rate, tremors, seizures, and even death. Sadly dogs do die from chocolate toxicity so it’s best to pay close attention to where you keep it in your home if you have dogs.

The amount of theobromine (the main toxin) in chocolate depends on the type, with generally the bitter chocolates having higher concentrations than the sweeter chocolates.

So, if a 50-pound dog ate just three ounces of baker’s chocolate (three of those little squares in the package), he would start becoming restless, then hyperactive, then start having heart arrhythmias, tremors, then seizures and possibly death within several hours. But this same dog would have to eat six ounces of semi-sweet chocolate (half a bag of semi-sweet chocolate chips) to have the same effect, and 16 ounces of milk chocolate.

Chocolate also has a lot of fat, and in most cases of milk chocolate ingestion, these dogs don’t have seizures and death, but they can have a lot of vomiting and diarrhea from the sudden high sugar, high fat meal.

Typically, it’s the dark chocolate ingestion that gets dogs into the hospital. Hershey’s Special Dark chocolate bars and, more recently, the 70 percent and 80 percent cacao gourmet chocolate bars are big troublemakers. Getting into a bag of semi-sweet chocolate chips will also do it.  We don’t commonly see serious milk chocolate toxicity, though small dogs are the exception; it doesn’t take a large amount for their smaller weights.

If your dog does get into some chocolate, call your veterinarian right away for advice.  You can also do a Google search for “chocolate toxicity calculator” and find several references to help you determine if your dog ate a dangerous amount.  But if you are unsure, call your veterinarian immediately. Cats are actually more sensitive to chocolate than dogs, but they simply don’t have a sweet tooth and it’s rare to see cats for this problem!

Treatment of chocolate ingestion usually means making them vomit, then giving them activated charcoal (a gross black paste to help stop further absorption of toxins), and fluid administration.  Most dogs come to us right after they ate the chocolate and they do well.  The dogs who got into the chocolate 6-8 hours earlier can be in pretty rough shape and they are much harder to treat. Take home message: be very careful with where you are keeping your holiday chocolate and save yourself a vet visit!

Another common sweet for us that is life threatening for dogs is xylitol. Xylitol is an artificial sweetener that is commonly used in chewing gum and sugar-free snacks. It is thought that xylitol has some antibacterial properties and dentists often recommend chewing gum that contains xylitol. So it’s great for humans, but terrible for dogs.

There are two toxic effects of xylitol ingestion in dogs, hypoglycemia and liver damage.

In dogs, the canine pancreas confuses xylitol for real sugar and releases a lot of insulin to lower the blood sugar.  This rush of insulin starts removing existing real sugar from the bloodstream, causing dangerously low blood sugar levels that lead to disorientation, weakness, tremors, and even seizures. These effects can take up to 12 hours to correct.

The other toxic effect of xylitol is liver damage. We do not know exactly why this happens, but it does take a higher dose of xylitol to cause it. Dogs can go into severe liver failure and die. These dogs tend to have signs of hypoglycemia first, so they may have treatment instituted before too much liver damage has occurred.

A 50-pound dog has to eat six to eight pieces of gum to get sick, whereas a 10-pound dog has to eat only one or two pieces. The take home message: be very careful with where you keep your chewing gum.

As we head into the holiday season, our homes become filled with joy and of course a little chaos. Be sure to try to keep chocolate, gum, and other sweets away from dogs and your holiday season will be much more enjoyable!