ABC's Political Radar has a data point, but misses the interpretation:

Romney Attacks Go to the Dogs
ABC News' John Berman Reports:

Mitt Romney's latest weapon in his barrage of jabs at Mike Huckabee? A dog named Spike.

A dog named Spike that likes to write letters. It is a piece of direct mail sent to Iowa voters, purportedly from Spike that begins, "Dear Iowa Republicans..."

It goes on to say, "You might have read about how Mike Huckabee raised taxes even more than Bill Clinton..."

Spike is apparently referring to the growing litany of mailings and "contrast" television ads where Mitt Romney is trying to paint Mike Huckabee as a liberal.

Spike continues: "What makes me barking mad? Mike Huckabee raised taxes on dog groomers! He went too far when he taxed the people who make me beautiful."

It is signed, "Bow Wow, Spike." It seems to be a genuine attempt at light-hearted humor on the campaign trail.

"Genuine," "light-hearted," and "humor"?

From Willard Mitt Romney?

John, what have you been smoking? That's just so implausible there has to be a better reason: