PawsMathWhy chocolate is poisonous to dogs
Chocolate contains two stimulants called methylxanthines: theobromine and caffeine. Humans break them down within hours, but dogs process theobromine very slowly. Its half-life in dogs is around 17 hours. The stimulants build up and over-excite the nervous system and heart.
Toxic dose thresholds
| Dose (mg per kg) | What can happen |
|---|---|
| Under 20 | Usually no or mild signs; upset stomach possible |
| 20–40 | Vomiting, diarrhea, excessive thirst, panting, restlessness |
| 40–60 | Racing heart, abnormal heart rhythm, high blood pressure, tremors |
| 60 and above | Seizures, collapse, potentially fatal |
How much theobromine is in chocolate?
Approximate methylxanthine content (theobromine + caffeine) used by this calculator:
| Chocolate type | mg per oz | mg per 100 g |
|---|---|---|
| White chocolate | ~1 | ~3 |
| Milk chocolate | ~64 | ~225 |
| Semisweet / chips | ~150 | ~530 |
| Dark 60–69% | ~200 | ~705 |
| Dark 70–85% | ~250 | ~880 |
| Baking (unsweetened) | ~390 | ~1,375 |
| Cocoa powder | ~650 | ~2,290 |
Values vary by brand and cacao origin, so treat results as an estimate and lean toward caution.
What to do if your dog ate chocolate
- Remove any remaining chocolate and keep the wrapper. It shows the type and amount.
- Estimate the dose with the calculator above.
- Call your vet or a pet poison helpline straight away, even if your dog seems fine.
- Don’t induce vomiting unless a professional tells you to.
- Watch for signs for the next 72 hours: vomiting, diarrhea, restlessness, panting, trembling, a fast heartbeat or seizures.
Chocolate is only one of several common kitchen dangers. See our list of toxic foods for dogs.
More questions
How much chocolate is toxic to a dog?
Mild signs (vomiting, diarrhea, restlessness) can appear at around 20 mg of theobromine and caffeine per kg of body weight. Heart effects appear around 40–50 mg/kg and seizures around 60 mg/kg. For a 20 lb dog, that can be as little as half an ounce of baking chocolate or about 3 oz of milk chocolate.
Which chocolate is the most dangerous for dogs?
The darker and more bitter the chocolate, the more dangerous. Cocoa powder and unsweetened baking chocolate are the worst, followed by dark chocolate, then semisweet and milk chocolate. White chocolate contains almost no theobromine but its fat and sugar can still cause stomach upset or pancreatitis.
How long after eating chocolate will a dog show symptoms?
Signs usually start 6–12 hours after eating and can last 24–72 hours because dogs clear theobromine slowly. Do not wait for symptoms. Treatment such as inducing vomiting works best within the first 1–2 hours.
Should I make my dog vomit at home?
Only if a veterinarian or poison helpline tells you to and explains how. Inducing vomiting the wrong way can be dangerous, and it is not appropriate for every dog or situation.
My dog ate chocolate but seems fine. What should I do?
Use the calculator to estimate the dose, then call your vet or a pet poison helpline anyway. A dog can look normal for hours before signs appear, and early treatment is easier, cheaper and safer.
Sources
- Chocolate Toxicosis in Animals, Merck Veterinary Manual
- FoodData Central (theobromine and caffeine content of chocolate products), U.S. Department of Agriculture
- Animal Poison Control Center, ASPCA
A calculator can't examine your dog. If anything seems off, or you're unsure, your veterinarian is the right person to ask. Disclaimer