Dogs are prone to ingesting poisonous substances due to their tendency to put anything in their mouths. Common household poisons include human foods like chocolate, medications, and various plants. Signs of poisoning include abnormal behavior, vomiting, diarrhea, and weakness. If a dog is suspected of ingesting something toxic, the owner should collect any remaining substance or vomit as evidence, call the vet immediately, and follow the vet's instructions for treatment. Pet owners should thoroughly proof their homes and seek veterinary advice if they suspect poisoning.