Why is chocolate toxic for dogs?

Why is chocolate toxic for dogs? Because it contains theobromine and some caffeine. Dogs break these substances down very slowly, so they have a much stronger effect on them than on us. How dangerous it gets depends on the type, the amount and your dog’s weight: the darker the chocolate, the more theobromine it contains. If your dog has eaten chocolate, call the vet straight away and don’t wait until he shows signs.

Why is chocolate toxic for dogs?

Cocoa contains substances from the methylxanthine group, mainly theobromine and, in smaller amounts, caffeine. They stimulate the heart and nervous system. A dog takes a very long time to break down theobromine: after about 17.5 hours, only half of it has left the body. This means even smaller amounts build up and can overwhelm the heart, circulation and nerves.

Which chocolate is the most dangerous?

From what amount does it become dangerous?

First signs such as vomiting, diarrhoea and strong thirst are possible from about 20 mg of methylxanthines per kilogram of body weight. From about 40 to 50 mg per kilogram the heart can be affected, and from about 60 mg per kilogram seizures may occur. A rough example: in a 10 kg dog, less than 40 g of dark chocolate can already cause first signs. But dogs differ in how sensitive they are. So don’t do the maths yourself; call the vet and tell them the type, amount and weight.

How do you recognise chocolate poisoning?

• First: Strong thirst, vomiting, diarrhoea, a bloated belly and restlessness.
• Later: Your dog is hyperactive, needs to pee a lot, walks unsteadily, trembles or seems stiff.
• Severe cases: A very fast or irregular heartbeat, fever and seizures.
• Timing: Signs usually start 6 to 12 hours after eating and can last up to 72 hours in severe cases.

What to do if your dog has eaten chocolate

Call the vet or the animal clinic straight away, even if your dog still seems fine. Keep the packaging to hand and estimate how much is missing. If he ate it less than about two hours ago, the vet can make your dog vomit. Don’t try this yourself with home remedies. Depending on the amount, the vet gives activated charcoal, fluids and medication for the heart and nerves, and monitors your dog until the theobromine has been broken down.

The fat is a risk too

Many chocolates and pralines contain a lot of fat. In sensitive dogs, that much fat can trigger inflammation of the pancreas, even if the amount of theobromine was small. This also applies to white chocolate.

Advent and Easter: how to protect your dog

• Higher risk: A British analysis of veterinary records found dogs that had eaten chocolate almost five times as often at Christmas as on other days, and about twice as often at Easter.
• Advent calendar: Hang it high enough that your dog can’t reach it.
• Presents: Don’t put chocolate under the tree and don’t leave guests’ bags open.
• Brief your visitors: Ask guests and children not to give your dog anything from their plate.
• Dog treats: If you want to spoil your dog, give him a treat that is made for dogs.

Frequently asked questions

Sources

• Hayes C.: Chocolate Toxicosis in Animals, MSD/Merck Veterinary Manual, accessed 2026.
• Noble P.-J. M. et al.: Heightened risk of canine chocolate exposure at Christmas and Easter, Veterinary Record 2017.

Chocolate does not belong within a dog’s reach, especially during Advent. If your dog has had some after all, a quick call to the vet is what matters most.

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