Dee Dee,
black dogs are very hard for most camera's auto-focus to lock on to. As you know, I shoot a lot of black dogs and I use only the center focus spot and try to focus on the outline of the dog so that there is contrast between the dog and the background. I focus, lock it in by depressing the shutter half-way and hold it there and then recompose and press the shutter the rest of the way.

If you don't have a focus problem in other situations, then try the above approach. Also, in a studio set-up, make sure you're using halogen modeling lights in your strobes. They give off more illumination and that will help your auto-focus lock in.

Give Hallie a kiss for me.

Jim