Is Chocolate Poisonous to Dogs? Amounts, Signs

Chocolate comes from cocoa, which contains stimulants called methylxanthines, mainly theobromine and, to a lesser extent, caffeine. People break these down quickly. Dogs do it slowly, so the compounds build up in the body and affect the heart, the nervous system, and the digestive tract.

That is why even a fairly small amount can be a problem for a small dog, and why signs can last a long time, sometimes a day or more.

The darker and less sweet the chocolate, the more theobromine it contains. Approximate levels vary by product, but the pattern is consistent.

• White chocolate: very little theobromine, though it is high in fat and sugar and can still upset the stomach.
• Milk chocolate: a moderate amount, roughly 2 milligrams per gram.
• Dark chocolate: several times more, often around 5 to 6 milligrams per gram.
• Baking (unsweetened) chocolate and cocoa powder: the most concentrated, commonly in the range of 14 to 15 milligrams per gram or more.
• Cocoa mulch and cocoa bean shells: can contain high levels too and should be kept away from dogs.

Note: These figures are approximate and vary by brand. Check the product and contact your veterinarian, who can use the exact product and your dog's weight.

Veterinary references commonly describe mild signs, such as restlessness and stomach upset, from around 20 milligrams of theobromine per kilogram of body weight, effects on the heart from about 40 to 50 milligrams per kilogram, and seizures from around 60 milligrams per kilogram or more.

As a rough illustration only, not a safe limit: for a 10 kilogram dog, 20 milligrams per kilogram is about 200 milligrams of theobromine. That could be reached with roughly 100 grams of milk chocolate (a large bar), around 35 to 40 grams of dark chocolate, or around 15 grams of baking chocolate. For a 5 kilogram dog, halve each of those amounts.

These calculations are why the question "how much is too much" has no simple answer. Small dogs, dogs with heart conditions, and dogs who eat concentrated chocolate are at the highest risk, and any exposure is worth a call.

Signs usually start within a few hours, but can be delayed up to about 12 hours or more, and can last a day or longer.

• Vomiting and diarrhea, often with a very thirsty dog.
• Restlessness, pacing, and hyperactivity.
• Panting and a fast or irregular heartbeat.
• Muscle tremors or stiffness.
• Frequent urination.
• Seizures, collapse, or coma in severe cases.

Act quickly and calmly. The earlier a vet can advise, the more options there are.

1. Take away any remaining chocolate and keep your dog from eating more.
2. Find the packaging and note the type of chocolate, the brand, and the weight or number of pieces eaten.
3. Weigh your dog, or note the approximate weight.
4. Call your veterinarian or an emergency clinic. In the US, the ASPCA Animal Poison Control Center (888-426-4435) and the Pet Poison Helpline (855-764-7661) answer around the clock and may charge a fee.
5. Follow the advice you are given. It may include inducing vomiting at a clinic, giving activated charcoal, or monitoring and supportive care.
6. Do not give home remedies or try to make your dog vomit unless a veterinarian instructs you to.

Chocolate is not only in bars. Brownies, cookies, chocolate-coated nuts or raisins, hot chocolate mix, cocoa powder, and chocolate liqueurs all count. Chocolate-covered espresso beans add caffeine on top.

Check the ingredient list for xylitol, found in some sugar-free sweets and baked goods. Xylitol is a separate and urgent danger to dogs, and it can cause a rapid drop in blood sugar and liver damage.

Wrappers, foil, and ribbons can also cause blockages if swallowed, so a dog that has eaten a wrapped gift should be checked for these as well.

Most cases are accidents: a bag left on the sofa, a stocking within reach, an advent calendar on a low shelf. A few household habits cut the risk.

• Keep chocolate in closed cupboards or on high shelves, never in bags on the floor.
• Put gifts and stockings out of reach until they are opened.
• Tell visitors, especially children, to keep chocolate away from the dog.
• Teach and practice leave-it, with a reward for ignoring dropped food.
• Know your nearest emergency vet, and keep the poison helpline numbers on your phone.