A few hours later, the owner noticed the dog looked very lethargic. He was resistant to move, incoordinated and was retching. The Labrador was kept at the clinic for the weekend and recovered completely. Although he had ingested quite a bit of dough, an animal needs to eat only a small amount to cause a problem, because bread dough can rise many times its size. Chocolate contains a chemical, theobromine, which is poisonous to all dogs.
Different dogs react differently to it.
Theobromine can trigger epileptic seizures, fatal cardiac irregularity, can irritate the gastrointestinal tract and cause internal bleeding which can kill the dog within a day or so. Theobromine is also present in differing amounts in different kinds of chocolate. Theobromine will stay in the bloodstream between 14-20 hours. It goes back into the bloodstream through the stomach lining and takes a long time for the liver to filter out. If your dog has eaten chocolate, contact your vet immediately.