Think in this case the tight crop looks better because it removes all the bits so to speak, the half ears and the half back. Cropped this tight show just the nature and beauty of this dogs face and expression the loose crop does not draw the eye in so tight to the expression. More space in front of the nose would have been better if possible.

Think where animals are the main subject you should include the whole subject if possible placing them in the rectangle of the photograph so the eye is drawn to them and ignores the surroundings. If you wish to take the head then you must crop in a suitable place, with animals the neck making sure you include the ears and nose or cut them right off.

Mind you like all things photographic it can happen that the best and most interesting shot will be the one that breaks all the rules.

She is a beauty, one of my most fave breeds xx

I like 3 and 4 the most It is hard when you have a dog with huge ears, to get up close without chopping the ears I am forever doing it

I would say, DONT crop - go back out there and take more portraits of your dog, in PORTRAIT orientation. You will see the difference immediately for yourself.

Include ears, head and equal part chest.