My cat Caught a rat/mouse. waht can I do for the rodent?

My cat caught a rat recently (5 minutes ago) and I don't have antibiotics for rodents, what can I do other than take this wild rat to the vet and pay for a bill that I can't afford because my dog has to go to the vet for an appointment in 2 days. If there is no home remedy, what are the chances the rat will survive?