My dad had rats in his grocery store; huge sewer rats about a foot long plus tail; they multiplied so fast it was unbelievable. He had a 22 pistol with hollow points and we'd shoot 'em whenever we could find 'em but they were subversive and hard to trap. Of course we'd lay out traps too, but they'd crawl down in the well and die and we'd have no water half the time. Frustrated, dad went to his dad's farm who'd had a litter of barn cats and brought home 5 1 yr. olds. They mated and re-mated and in no time we had almost 50 cats we were feeding and they were utterly vicious! They'd corner and attack those rats and fight them like tigers and drove them off; we narrowed the litters to 8 or 10 cats and only 1 or 2 were house pets, the rest were outside cats that lived down cellar did a great job maintaining the property! Lucky we owned a grocery store, we'd buy an extra case of cat food and would have to open up 10 or more cans at a feeding, but it was well worth it... they were kings and queens in the store; laze around all day long and earn their keep at night, lol!