A challenging subject with the contrast in tones. You could not have done better. It looks natural but I bet you even posed this hansomly proud pet. Well done.
I rather like this. Even with the black spots near the hind quarters and ear, there appears to be separation/definition between the dog and background. Nice job!
I suspect this is a fine portrait, but I think your processing for this medium has let the shot down; there is obviously definition present in all areas of the shot, but I rather think the blacks of the dog's fur have been taken too far towards the black fo the background to make good viewing; certainly around the eyes it's very difficult to make out any kind of expression, as everything tends towards the same black. It's a difficult balance to make, especially for web display, where you also have to contend with the variety of other people's monitors. That said, I think you definitely needed to bring the dark fur areas forward from the background more.