Contact the veterinarian of any dog that has eaten chocolate and let the vet know how much and what kind of chocolate the dog has eaten and how long it has been since the dog ate the chocolate, suggests VetsNow. This information allows the vet to determine the proper action.
The toxic ingredient in chocolate is theobromine, explains VetsNow. It is toxic at the rate of 100 to 150 milligrams per kilogram of the dog's weight. Different types of chocolate have different levels of theobromine. The darker or more pure the chocolate, the higher the concentration of theobromine and the less chocolate a dog has to eat for it to be toxic.