Kim,
without seeing the shot, it's a bit hard to say whether or not it can be salvaged. If it's a moving shot of a dog either in Conformation or Agility, then you really need to have all of the dog. That's one of those things where you err on the side of too much air around the dog and do your cropping in post-processing.

A lesson painfully learned is never crop too tightly in the camera. You can always crop later but you can't add stuff in later.

Good luck,

Jim