The Dark Side of Chocolate: Chocolate and Caffeine Toxicity in Pets

It is fairly common knowledge among pet owners that chocolate is bad for dogs and cats. However, what you might not know is that the concerning ingredient in chocolate (theobromine) and caffeine are sister compounds with similar effects. Along with theophylline, a drug used to treat asthma, these three compounds are known as methylxanthines. Theobromine can of course be found in chocolate candy, chocolate chips, cocoa powder, and baking chocolate. It is also important to keep in mind that our society’s collective sweet tooth has caused chocolate to find its way into a variety of other products including baked goods, cereals, fudge, lip balms, syrups, ice creams, pudding, beverages, and so much more! Caffeine is well known for being in coffee, tea, and related beverages, but it can also be found in energy drinks, sodas, medications, energy bars, herbal products, and a very small amount in chocolate.

Methylxanthines inhibit receptors in the forebrain and other parts of the body that ultimately cause brain stimulation, increased heart rate, and increased urination. While this process is the reason why many of us are unable to function without our morning cup of Joe, it can be dangerous for our pets. The brain stimulation can lead to seizures and coma, if enough is ingested. The effect of methylxanthines on the heart leads to abnormal heart rhythms resulting in risk of sudden death. For both theobromine and caffeine, when pets ingest smaller amounts it will usually only lead to gastrointestinal upset. However, when they ingest large amounts they often show gastrointestinal upset that progresses to these cardiovascular and neurologic signs.

Early signs of caffeine poisoning include vomiting, restlessness, and hyperactivity with a rapid progression to diarrhea, tremors, panting, weakness, unsteady gait (ataxia), and seizures. Sudden death and respiratory distress can occur in severe or untreated cases. Similarly, early signs of theobromine (chocolate) poisoning include vomiting, diarrhea, restlessness, and hyperactivity, with more severe cases progressing to tremors, increased urination, and seizures. Weakness, coma, and death can occur in severe or untreated cases.

The amount of chocolate or caffeine needed to lead to concern in pets is highly dependent on the type of chocolate or caffeine, the weight of the pet, and the species. As a rule of thumb, cats are more sensitive than dogs, and larger pets may tolerate larger amounts before showing signs. The type of product ingested is also important. For chocolate products, dark chocolate, semi-sweet, bittersweet, baking chocolate, and other chocolates with a higher percentage of cacao are more potent than milk chocolate, and require less to be ingested before causing signs. For coffee products, unbrewed coffee beans and grounds are considerably more potent than brewed coffee and used grounds. Decaffeinated coffee does have a marginal amount of caffeine that could lead to signs if enough is ingested. Also, keep in mind that some chocolate products, especially candy and gum, may have additional ingredients of concern, such as xylitol.

To help reduce the risk of poisoning, keep chocolate or caffeine products in your fridge, pantry, or tall cabinets, far out of reach of pets. Try not to leave sweet treats unattended. Be especially cautious around the holidays when there tends to be more chocolatey desserts, candies, and caffeine filled beverages around.

If you believe that your pet has accidentally ingested a chocolate or caffeine product, please seek veterinary attention immediately or call Pet Poison Helpline at 1-800-213-6680. Please have the packaging or ingredients available to help determine extent of concern.


Written by:

Written by Cecelia Harmon, Pet Poison Helpline DVM student extern, Virginia Tech class of 2023

Samantha Koch, CVT, Veterinary Information Specialist II, Pet Poison Helpline