Hi,
My tuppence worth.
I think the lighting is good, so I would try more with that set-up before changing anything.
Assuming you are doing it for the owners most people prefer to see the eyes, so this shot would work better if you were lower and more to the right (ie. more face on).
Cutting off the tail is a no-no for owners; it's different to cutting off enough to make it a portrait.
A lot of people would also expect more DOF so all the dog is sharp.
In this particular shot I don't like the little bit of background showing between the dog's left eye and ear.
More generally, check the subject has got clean feet and no gak in the corners of their eyes.
This is just my amateur experience of photographing friend's and our cats, but it looks like you are on the right track.
