Yes, rat poison is fatal to dogs. Within 2 hours after eating a large amount, dogs will develop symptoms and may die directly in severe cases. After the pet is discovered that the dog has accidentally eaten rat poison, the pet should be sent to the pet hospital for gastric lavage and detoxification as soon as possible. If the dog is discovered in time, the rescue can be successful. If the rat poison is not effective, the dog may experience symptoms such as physical discomfort, vomiting and diarrhea, but it still needs to be sent to the doctor for detoxification.