July 18, 2026
My dog ate chocolate. What matters is the dose
Dark and baking chocolate are the dangerous ones, milk chocolate is far weaker, and the maths depends on your dog’s size. How to work out calmly whether this is an emergency.
The wrapper is on the floor, the face is guilty, and somewhere in your head is the sentence "chocolate kills dogs". Sometimes that's true. Usually it isn't. Whether tonight is an emergency comes down to three numbers, and you can work them out while your heart rate comes back down.
The three numbers
How big is your dog. The poison in chocolate is theobromine, a stimulant dogs clear very slowly, and every threshold scales with body weight. Trouble starts around 20 mg of theobromine per kilo of dog. Around 40 to 60 mg per kilo it gets dangerous.
What kind of chocolate. This is the number people get wrong, because the range is enormous:
| Theobromine | In practice | |
|---|---|---|
| White chocolate | almost none | Fat and sugar, not a poisoning risk |
| Milk chocolate | ~1.5 to 2 mg per gram | It takes a lot: roughly a full 100g bar per 10kg of dog |
| Dark (70%+) | ~5 to 8 mg per gram | A few squares matter for a small dog |
| Baking chocolate, cocoa powder | ~14 to 26 mg per gram | Small amounts count. This is the dangerous shelf |
How much is actually gone. Find the wrapper, do the archaeology. Owners regularly discover half the bar under the sofa, and the difference between "a bar" and "half a bar" is the difference between an emergency and an early night.
Put together: a 30kg Labrador who stole two squares of milk chocolate has eaten maybe 25 mg of theobromine against a 600 mg trouble line. Watch for a grumbly tummy and forgive her. A 5kg terrier into half a bar of 85% dark has crossed the line twice over: that is a vet, now, not a wait-and-see.
If the maths says trouble, or you can't do the maths
Call your vet or a pet poison line with the three numbers ready: weight, type, amount. They run the same arithmetic and tell you whether to come in. If you use Petus, it already knows the weight, so it asks only what kind and how much, and gives you the same calm dose-based read: two milk-chocolate buttons gets reassurance, not panic, and a real emergency gets "go now" plus the nearest open clinic.
One thing not to do: don't make your dog vomit at home. The salt and hydrogen-peroxide tricks on the internet cause their own emergencies, and safe vomiting is a clinic procedure that only helps in the first couple of hours anyway.
What poisoning actually looks like
Signs usually arrive within 2 to 12 hours. Mild: restlessness, whining, a racing pulse of activity, vomiting, diarrhoea, big thirst. Serious: a pounding heart, muscle tremors, wobbliness, and in bad cases seizures. If any of the serious list is already happening, stop calculating and go.
The other side of that timeline is reassuring: a dog who is completely normal a full day after the theft is very likely in the clear. Theobromine doesn't stockpile in the body between occasional thefts either, though that is an argument for better cupboard security, not for sharing.
The edge cases
Chocolate cake and cookies count by the chocolate actually in them, which per slice is usually modest. The exception is anything built on cocoa powder, brownies especially, which counts as dark. And cats: the same maths applies, but cats can't taste sweetness and almost never volunteer, which is why you never hear about it.