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My dog ate chocolate: what to do now

By Your Dog Magazine editors · Updated · How we check

Call your vet, an emergency clinic or ASPCA Animal Poison Control at (888) 426-4435 now if your dog ate dark, baking or a lot of milk chocolate. Then use the steps and figures below.

Do this now

  1. Find the wrapper. Note the type of chocolate and how much is missing.
  2. Weigh your dog, or use the last vet weight.
  3. Enter both into the chocolate toxicity calculator.
  4. Call your vet or a poison line ((888) 426-4435 or 855-764-7661) and give them those numbers. Don't wait for symptoms.

Why chocolate is toxic

Chocolate contains methylxanthines: theobromine and caffeine. Dogs process them slowly, so they build up and overstimulate the heart and nervous system.

How much is dangerous

The Merck Veterinary Manual gives these doses of methylxanthines per kilogram of body weight:

Dose What can happen
20 mg/kg Mild signs: vomiting, diarrhea, extra thirst
40 to 50 mg/kg Heart effects: racing or irregular heartbeat
60 mg/kg or more Seizures

How much is in each type of chocolate

Chocolate Methylxanthines per ounce
Cocoa powder about 807 mg
Unsweetened baking chocolate about 440 mg
Semisweet and dark chocolate about 150 to 160 mg
Cocoa bean hulls (mulch) about 255 mg
Milk chocolate about 64 mg
White chocolate about 1 mg

So the same ounce of baking chocolate carries about seven times the dose of milk chocolate. Merck notes that about 1 ounce of milk chocolate per pound of body weight is potentially lethal.

Symptoms and timing

Signs usually start within 6 to 12 hours and can last up to 72 hours in severe cases: vomiting, diarrhea, thirst, restlessness, panting, a fast heartbeat, tremors and seizures.

Source: Merck Veterinary Manual, "Chocolate Toxicosis in Animals" (reviewed Sep 2024, updated Feb 2026); ASPCA Animal Poison Control, "People Foods to Avoid Feeding Your Pets". Checked October 17, 2026.

Frequently asked questions

How much chocolate will hurt a dog?

It depends on the type and your dog's weight. Merck lists mild signs from about 20 mg of methylxanthines per kg, heart effects from 40 to 50 mg/kg and seizures from 60 mg/kg. Use the calculator, then call your vet.

Is white chocolate dangerous for dogs?

White chocolate has almost no methylxanthines (about 1 mg per ounce), but it is fatty and sugary and can still upset the stomach.

When do symptoms of chocolate poisoning start?

Usually within 6 to 12 hours of eating it, according to the Merck Veterinary Manual.

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