Dogs that eat rat poison will usually show symptoms in about half an hour, and then die within a few hours. If it is chronic rat poison, they may die about three days after poisoning. It depends on the toxicity of the rat poison and the How much did the dog eat. When you find that your dog has eaten rat poison, you should immediately induce vomiting. If the dog cannot vomit, you need to send it to a pet hospital for treatment immediately.