Dusty is intelligent in an obedient kind of way. He's quick to learn things and has alot of common sense. (Like don't jump out of the truck while moving, don't walk out to sniff moving cars, etc...)

Roxy, on the other hand is intuitive. (At least I think that is the word.) She is very keen on picking up on if people are old, young, sick, healthy, playful, mean, etc... She is excellent at judging characters and acts accordingly. And she is very intelligent when it comes to escaping. I've seen her do everything from scoot her dog house against the fence and stack wood on it to escape, to unlatch complicated locks.

But the few times Roxy and Dusty escaped, I know it was Dusty's smarts that kept Roxy alive.