A name from the old BBC children's programme "The Magic Roundabout" - Zebedee (could be nicknamed Zeb)
Our current dogs' names are Max and Zuzu, and I find that Zuzu is a great name for any dog that's playful. It's also fun to say
Some obvious (to me) Z name references (yes I'm old): Zevon (aaa-oooooo, newfies of London) Zurg (or Zerg... when he goes tearing through the yard, it'd be a Zerg rush) Zazu (or Zazoo for a more fun spelling) Zuul (there is no pupper, only Zuul) Ziven (not a reference but I think it's a cool name) Zorg (bonus points if you can get his hair just right) Zombo (or Zombocom for maximum proto-memeage) Zoomer Zoolander Zardoz (too close to Zara) Zora (Another Legend of Zelda reference, but too close to Zara) Shyguy already suggested Zed, and newfies ARE Canadian...
I'm not sure if anyone said this one yet but i'm going with Zamboni. If had another vote i would vote for Zinc, the one that ellisbrewer mentioned.