The subject of this picture appears to be the dog, not the Master giving the dog a bath. I think if there was more emphasis on the bath and less on the dog it would be a little more authoritative. Good looking dog though.
now that's a good doggie! and i bet 10 minutes later she was rolling around, getting stinky again (at least that's what mine do!). great colors. might be a little stronger if cropped in a bit tighter. wonderful expression, not easy to capture. as for the challenge, it's a stretch, and hopefully you won't be hammered too much along those lines.
I don't know how this convey's authority, but I like the personality the photographer captured in the dog's expression. He looks unhappy to me, eduring this bath. The lighting is a distraction on the dog, but it enhances the human arm.