PeggySue,
I shoot with room to crop and leave the creative decision-making to post-production. I guess that comes from shooting ring formals where everything has to be in the shot so you leave yourself "bleed room".

I actually prefer the second assuming the shot was taken for sale to the dog's owner. I believe that most owners could care less about artsy fartsy cropping and want to see as much of the dog in a portrait as possible.

When I shoot my own dogs, I will often crop tightly to emphasize a particular feature -- Rowdy's eyes, for example.

As Jim and Bob said, it depends on the purpose of the image. If you're selling it as a portrait, I think the second is more salable. If you're shooting for your portfolio, the first is more artistic.

Jim