How this is calculated
Dose in mg/kg = grams of chocolate × methylxanthine content per gram ÷ body weight in kg. Theobromine and caffeine are added together, as veterinary toxicologists do, because both act on the heart and nervous system. For a known cocoa percentage, the content of unsweetened chocolate (15.5 mg per gram) is multiplied by that percentage: a 70% bar gives about 10.9 mg per gram.
| Product | Theobromine and caffeine |
|---|---|
| White chocolate | 1.1 mg/oz (0.04 mg/g), negligible |
| Milk chocolate | 64 mg/oz (2.3 mg/g) |
| Dark and semisweet chocolate | 150 to 160 mg/oz (5.3 to 5.6 mg/g); 160 used here |
| Baking (unsweetened) chocolate | 440 mg/oz (15.5 mg/g) |
| Cocoa powder, dry | 807 mg/oz (28.5 mg/g) |
| Cocoa bean hulls (mulch) | 255 mg/oz (9 mg/g); some mulches have had most of it removed |
| Dose | What is reported in dogs |
|---|---|
| About 20 mg/kg | Mild signs: vomiting, diarrhea, increased thirst, restlessness |
| 40 to 50 mg/kg | Severe signs, heart effects such as a racing or irregular heartbeat; 40 used here |
| 60 mg/kg and above | Tremors and seizures |
| 100 to 200 mg/kg | Published lethal dose (LD50) of theobromine and caffeine; deaths occur below it |
Where published figures form a range, the calculator uses the higher content and the lower dose, so it leans toward a higher risk estimate.
What the estimate cannot tell you
- Content varies between brands and batches. Assorted chocolates are safest calculated as if all of it were the darkest kind in the box.
- Signs usually begin 6 to 12 hours after eating and can last up to 72 hours. A dog that seems fine now may not be later.
- Rich, fatty chocolate products can cause pancreatitis 24 to 72 hours later, whatever the methylxanthine dose. Foil and wrappers can block the gut.
- Dogs with heart disease are at extra risk, and methylxanthines pass to unborn and nursing puppies.
Sources
- Merck Veterinary Manual, “Chocolate Toxicosis in Animals,” C. Hayes, ASPCA Animal Poison Control Center; full review September 2024, updated February 2026. Content table, dose levels, LD50.
- S. Gwaltney-Brant, “Chocolate intoxication,” Toxicology Brief, Veterinary Medicine, February 2001, ASPCA Animal Poison Control Center. Content table, dose levels, timing of signs, pancreatitis risk.
Reviewed November 2026. This calculator gives an estimate, not a diagnosis, and does not replace a veterinarian. Published doses come from case reports and poison-center experience; individual animals differ.