Dog Chocolate Toxicity Calculator NZ

If your dog has eaten chocolate, ring your vet or your nearest after-hours veterinary clinic now, before you finish reading this. Do not wait for symptoms and do not wait for a calculator to tell you whether it is serious. Treatment is far easier and far more effective in the first couple of hours, while the chocolate is still in the stomach and can be brought back up, and a vet would much rather take a call about a dog that turns out to be fine than see one that was watched at home for six hours first. This tool exists to help you describe the situation accurately over the phone, not to help you decide whether to make the call. Enter your dog's weight, the type of chocolate and roughly how much it ate, and it estimates the theobromine dose in milligrams per kilogram of body weight, which is the figure veterinary references use to judge severity. Every number here is an estimate built on published average theobromine contents, and real products vary widely.

Ring your vet now. Do not wait for this calculator, and do not wait for symptoms. If the chocolate went down in the last couple of hours a vet can usually bring most of it back up, and that window closes. Take the wrapper with you so the cocoa content can be read off the label.

kg
g
Serious
Ring a vet now. This is an estimate, not a diagnosis.
Theobromine swallowed560 mg
Dose per kg of body weight56 mg/kg
Amount usually below any signs36 g
Amount at the emergency threshold107 g

A low reading is not a reason to stay home. Theobromine content varies widely between products, the amount eaten is almost always a guess, and dogs differ in how they handle it. Chocolate also contains caffeine, and many chocolate foods contain raisins or xylitol, both of which are more dangerous to dogs than the chocolate is. Ring your vet whatever this says.

How it works

The toxic compound in chocolate is theobromine, a stimulant closely related to caffeine. People clear it from the body in a few hours. Dogs take far longer, about 17.5 hours to clear half of it, so it accumulates to levels that affect the heart and the nervous system.

The calculation has two steps. First, the amount of theobromine swallowed: the weight of chocolate eaten multiplied by the theobromine content of that type. Second, the dose relative to the animal: that total divided by the dog's weight in kilograms. It is the second figure, milligrams per kilogram, that determines severity, which is why the same biscuit is trivial for a labrador and dangerous for a chihuahua.

What the dose bands mean

Veterinary references group the response roughly as follows. Under 20 mg/kg, signs are usually absent or limited to an upset stomach. From 20 to 40 mg/kg, expect vomiting, diarrhoea, restlessness and increased thirst. From 40 to 60 mg/kg, cardiac effects become likely, including a racing or irregular heartbeat. Above 60 mg/kg, seizures are possible and the situation is an emergency.

The type of chocolate matters more than the amount. Cocoa powder carries well over a hundred times the theobromine of white chocolate by weight, so a small spill of cocoa is a far bigger problem than a whole white chocolate bar.

Worked example

A 10 kg dog that has eaten a 100 g block of dark, semi-sweet chocolate.

Semi-sweet dark chocolate carries roughly 5.6 mg of theobromine per gram, so 100 g contains about 560 mg. Divided across a 10 kg dog, that is 56 mg/kg, which sits in the band where cardiac effects are likely. That is a serious reading and needs a vet immediately.

For this dog and this chocolate, 36 g would be the point at which signs usually start to appear, and 107 g would reach the emergency threshold. The block it ate is much closer to the second figure than the first.

The same 100 g block eaten by a 35 kg labrador works out at 16 mg/kg, which is below the threshold where signs normally appear. Still ring the vet. The block might have been 85 per cent cocoa rather than semi-sweet, and the dog might have eaten more than you found wrapper for.

Related calculators

Data sources: Theobromine content per gram and the toxic dose bands follow the Merck Veterinary Manual: milk 2.3 mg/g, dark 5.3 to 5.6, baking 15.5, cocoa powder 28.5. Content varies between products, so where a range is published this calculator uses the upper end. Published figures for white chocolate range from about 0.04 to 0.25 mg/g; the higher is used here.

Frequently asked questions

How much chocolate is toxic to a dog?

It depends on the dog's weight and the type of chocolate. Signs typically begin around 20 mg of theobromine per kilogram of body weight. For a 10 kg dog that is about 36 g of dark chocolate, 87 g of milk chocolate, or as little as 7 g of cocoa powder. Ring a vet regardless of the amount.

What should I do if my dog ate chocolate?

Ring your vet or an after-hours veterinary clinic immediately, before symptoms appear. If the chocolate was eaten within the last couple of hours a vet can often induce vomiting and remove most of it. Take the wrapper with you so the cocoa content can be read off the label.

How long does it take for chocolate to affect a dog?

Signs usually appear within 6 to 12 hours, but theobromine has a long half-life in dogs of about 17.5 hours, against 2 to 3 hours in people, so effects can last for days. Waiting for symptoms before acting removes the window in which treatment is simplest.

Is white chocolate dangerous for dogs?

White chocolate contains very little theobromine, around 0.25 mg per gram, so theobromine poisoning is unlikely. It is still high in fat and sugar, which can cause pancreatitis, and any wrapper or foil eaten with it is a separate risk.

What are the signs of chocolate poisoning in dogs?

Vomiting, diarrhoea, restlessness, panting and increased thirst come first, followed at higher doses by a racing or irregular heartbeat, muscle tremors and seizures. If you see any of these after known chocolate exposure, treat it as an emergency.