My dog ate chocolate. What do I do?

Why chocolate is toxic to dogs

Chocolate contains theobromine, a stimulant in the methylxanthine family that dogs metabolise far more slowly than humans. While a human processes theobromine within hours, a dog's system takes much longer, allowing it to accumulate to toxic levels. The toxicity causes stimulation of the heart and nervous system, leading to vomiting, diarrhoea, elevated heart rate, muscle tremors, and in severe cases seizures and cardiac failure. The symptoms can take six to twelve hours to develop fully, which is exactly why you do not wait to see if they appear.

Which chocolates are most dangerous

Theobromine concentration varies sharply by chocolate type. Baking chocolate contains the highest concentration, around 400 to 450mg per ounce. Dark chocolate follows at 135 to 450mg per ounce depending on cocoa percentage. Milk chocolate is lower at around 44 to 64mg per ounce. White chocolate contains almost no theobromine and is not a significant theobromine risk, though its fat and sugar content can cause pancreatitis. A small amount of dark or baking chocolate can be toxic to a small dog; a larger amount of milk chocolate can also be toxic to any dog.

What to tell the vet

The vet needs three things: the type of chocolate, the estimated quantity in grams or ounces, and your dog's weight in kilograms or pounds. With those numbers they can calculate the milligram per kilogram theobromine dose and determine whether it is a toxic dose. They will also want to know how long ago the chocolate was eaten, whether your dog has shown any symptoms, and whether your dog has any existing health conditions. Be as precise as you can about the quantity; check the wrapper if you can find it.

What the vet may recommend

If the dog has eaten the chocolate within the last two hours and the dose is potentially toxic, the vet will often recommend inducing vomiting to remove as much theobromine as possible before it is absorbed. They may administer activated charcoal to prevent further absorption. In more serious cases, supportive care with intravenous fluids and heart monitoring is required. Do not induce vomiting at home without speaking to a vet first. Some home methods, including hydrogen peroxide, can cause additional harm.