If your dog consumes rat or mouse poison left out for vermin, you'll need to take him to an emergency veterinary hospital immediately. If he eats a poisoned rodent, he still needs prompt veterinary attention. While receiving the poison secondhand isn't quite as dangerous as eating it outright, this secondary poisoning can still kill your dog. Unfortunately, symptoms of secondary poisoning can take days to weeks to appear, so you might not connect a cause. Your vet can test for the different types of rat poison in your dog's system.
Symptoms of rat poisoning depend on the poison involved. If your dog ate a rat who consumed bromethalin, a common poison, he might experience appetite loss, muscle tremors and seizures, hind limb paralysis and balance issues. Your vet will give your dog medication to empty the digestive tract, along with other drugs for symptom relief. If the poison was an anticoagulant, which keeps blood from clotting and kills slowly, your vet can administer vitamin K to your dog as an antidote. If your dog just ate the rat, your vet can give your dog an emetic to force him to vomit.