One word: schipperke.
My bitch Corgi is death on rats. What I don't "get" is how she differentiates between rats and other rodents. We have yard sited bird feeders, and squirrels, chipmunks and rats all help themselves to the wastage on the ground. We turn Rosie loose, and she bee-lines for the rat, ignoring the others.
I’ve got one of those with a bit of beagle in her blood. Her prey drive DNA is activated by small critter movement.
Cats enjoy doing their job. How many humans can say that?