Common human foods as well as plants can be poisonous to dogs. If you suspect that your dog has been poisoned, you should contact your veterinarian or the pet poison hotline for guidance. Here are some articles that you may find helpul on symptoms that dogs may exhibit if they are poisoned.
In a poisoning, time is of the essence. Never wait for symptoms to become severe before seeking help, as early intervention can significantly improve the chances of a positive outcome.