I stand by CN's original statement. Here I shall present my case:
a) "you're such a howl" doesn't make any sense, while "you're such a ho" is completely logical and appropriate for the accompanying visual. Occam's razor.
b) earlier in the commercial, after they get their hair done one of the puppini's remarks that her hairdo was "worth the wag", wag obviously being a play on words meaning it was worth the "wait". "such a howl" is clearly another of these dog-themed puns, and what else could you substitute for howl other than ho?