Because old ways are always the best, right?
"How to make a Receit, that neither Rat nor Mouse shall eat or gnaw of your Cheese. The Weasel, the Rat, and Mouse, are at such deadly hatred one with the other, as that, if you put the brain of a Weasel into the Rennets or Curds whereof you intend to make your Cheese, neither Rats nor Mice will ever come to taste or eat thereof."~Thomas Hill, Naturall and Artificiall Conclusions (1649)
Of course there's also the goat method of chasing away rats:
via Ask The Past."The smell of a goat is obnoxious to the nostrils of rats; the two wont be friends and companions on any account whatever, and the introduction of goats to one's barn or premises will cause an immediate stampede of all the rats."~A. E. Youman, A Dictionary of Everyday Wants (1872)