Pet Poison Helpline gives the signs of chocolate poisoning in a dog and how to treat this type of poisoning in dogs.
Dark chocolate (85% cacao) has 810 mg per 100 g, so for a 70 kg adult human, you'd have to eat > 7 kilograms of dark chocolate to get close to the LD50. But a small dog will get sick and potentially die from just one bar of dark chocolate. there is a calculator here...
But what about white chocolate? Are some types less dangerous? How much is too much? This guide will break down the dangers of chocolate for dogs, the symptoms of chocolate poisoning, and what to do if your dog accidentally eats some.

As we can see from the illustration, Chocolate Poisoning Repercussions For Dogs has many fascinating aspects to explore.
Chocolate poisoning can cause a variety of problems which are extremely dangerous to your dog, the average vet bills for these cases are in excess of 300.
How much chocolate makes dogs sick? Toxicity to chocolate starts at around 20mg of theobromine per kilogram of body weight. In a small dog weighing 5kg, this means 100mg of theobromine (around 70g of milk chocolate or 20g of dark chocolate) will cause problems.

Chocolate poisoning can look similar to many poisonings or other conditions. Serious poisonings such as that caused by strychnine, amphetamines, pesticides, and some rodenticides can cause similar signs.