Someone on YouTube has added a much more appropriate soundtrack:
It really is more appropriate, and not just thematically: the music fits the action better. It's almost like the ad agency composed the animation to The Byrds, and only added the Creepy Nasal Monotone Singing Of Banal Ad Copy That Barely Qualify As "Lyrics" after the fact.
Found on Slate and BoingBoing; the Byrds remix was too funny not to share, and the original (posted by Purina itself!) is only embedded for context.