Two of mine decided to share a bad of mounds mini candy bars that were planned for halloween . I know there is not much total chocolate in them but it is dark chocolate , neither got the least bit sick .
here some info on choc -
It is not chocolate itself that is poisonous to dogs, it is the theobromine, a naturally occuring compound found in chocolate. Theobromine causes different reactions to different dogs: dogs with health problems, especially epilepsy, are more affected by theobromine than healthy dogs. Theobromine can trigger epileptic seizures in dogs prone to or at risk of epilepsy. The size of the dog will also be a major factor: the smaller the dog, the more affected it is by the same amount than a larger dog. Therefore, toxicity is described on a mg/Kg basis.
Furthermore, theobromine can cause cardiac irregularity, especially if the dog becomes excited. Cardiac arythmia can precipitate a myocardial infarct which can kill the dog.
Theobromine also irritates the GI tract and in some dogs can cause internal bleeding which in some cases kills them a day or so later.
Theobromine is also present in differing amounts in different kinds of chocolate. milk chocolate has 44-66 mg/oz, dark chocolate 450 mg/oz and baking/bitter chocolate or cocoa powder varies as much as 150-600 mg/oz. How much chocolate a dog can survive depends on its weight (and other unknown circumstances). Under 200 mg theobromine per kg body weight no deaths have been observed.
Theobromine will stay in the bloodstream between 14 and 20 hours. It goes back into the bloodstream through the stomach lining and takes a long time for the body to filter out. Because theobromine is eliminated through the liver rather than through the kidneys, it takes a long time to eliminate it.
Within two hours of ingestion, try inducing vomiting unless your dog is markedly stimulated, comatose, or has lost the gag reflex. If your dog has eaten a considerable amount of chocolate, or displays any of the above symptoms, take it to the vet without delay.
In the absence of major symptoms, administer activated charcoal. The unabsorbed theobromine will chemically bond to this and be eliminated in the feces. Burnt (as in thoroughly burnt, crumbling in hand) toast will do.