Julie,
black on black is one of my favorites. As for focusing, do your strobes have modeling lights? If they do, make sure you keep them on and you should have plenty of light for focusing.

For these types of shoots, I place the strobes on either side at approximately 45 degrees to the subject(s) and adjust them down (one or the other) if I want to create a shadow on one side. If not, I keep them both on full.

Because of the angle, the dogs tend to look at what I use to attract their attention and not at the strobes. I mount them high (at least 7 feet) and bounce them off of silver umbrellas. That will bring up the coats on black dogs.

These look pretty good. Fact is, you'll have to PP them to bring up the dogs and then bring down the backdrop. Here's one I did recently.



Once you bring the subject up in PP, you can just burn in the background.

Jim