Dog chocolate toxicity.

Worked example

A 20 lb (9.1 kg) dog eats 2 oz of milk chocolate. Milk chocolate is taken as 64 mg of theobromine per ounce, so 2 oz = 128 mg, and 128 / 9.07 = 14 mg/kg. That is below the 20 mg/kg band where mild signs start, but you should still call a vet. The same dog eating 2 oz of baking chocolate (450 mg/oz) gets 900 mg, about 99 mg/kg, in the seizure range: an emergency.

How it works

Chocolate and cocoa contain the methylxanthines theobromine and caffeine, which dogs clear slowly. Dose = theobromine eaten (mg) / body weight (kg). The Merck Veterinary Manual lists approximate bands: about 20 mg/kg mild signs (vomiting, restlessness, increased thirst), about 40 mg/kg cardiac signs (fast or irregular heartbeat), about 60 mg/kg and above seizures.

Theobromine per ounce used here, rounded up to be conservative: white 1.4 mg, milk 64 mg, dark or semisweet 160 mg, baking 450 mg, cocoa powder 810 mg. Real products vary a lot with cocoa percentage, and caffeine adds to the effect, so this is an estimate and can understate risk. Raisins, macadamia nuts, xylitol sweetener or other ingredients in the product can be dangerous on their own.

Small dogs, puppies, and dogs with heart disease are at higher risk. Treatment is most effective early, before the chocolate is absorbed. Never induce vomiting at home unless a vet tells you to.

Sources and basis (checked 2026-10-05): Merck Veterinary Manual, Chocolate Toxicosis in Animals (theobromine content and dose bands); ASPCA Animal Poison Control.

FAQ

How much chocolate is toxic to a dog?

Mild signs can start around 20 mg/kg of theobromine, which is roughly 1 oz of milk chocolate per 7 lb of dog or about 1 oz of dark chocolate per 18 lb of dog. Baking chocolate and cocoa powder are far more concentrated. Use the calculator and call a vet.

What should I do if my dog ate chocolate?

Call your vet or a poison line right away with the dog’s weight, the type of chocolate and the amount. Do not induce vomiting unless told to.

Is dark chocolate worse than milk chocolate?

Yes. Dark chocolate has about two and a half times as much theobromine per ounce as milk chocolate, and baking chocolate and cocoa powder have much more.

My dog ate a small piece of chocolate. Is it okay?

A small amount of milk chocolate is unlikely to reach the toxic range for a large dog, but it can for a small one. Estimate the dose and call a vet if you are unsure.

How long do signs of chocolate poisoning take?

Signs usually start within 6 to 12 hours and can last a day or more, because theobromine is cleared slowly.