My very first best-dog-in-the-whole-wide-world and still the smartest dog I've even known, Sheba, was a German Shepherd mix with a high prey drive. She would certainly kill any cat - or rabbit, squirrel, skunk, woodchuck - you name it - that she could catch. She killed every woodchuck in such a wide area around our neigborhood that one did not reappear in a neighbor's garden until 10 years after Sheba died. No lie.

The cats in our neighborhood - of which there were plenty - knew at any given moment where the nearest tree was. We had very speedy felines in our neighborhood - survival of the fittest. Sheba could never be trusted around any cat.