Not wanting to spend a huge amount of money on alien bees or similar, I bought a pair of large soft boxes with 1000 watt bulbs. 2000 watts sounds like quite a bit of light after all, and when they're on, things get pretty bright.
But.
It turns out that I'm walking a very fine line between having a shutter speed fast enough to freeze a restless dog, and aperture small enough to make sure everything is in focus, and an ISO slow enough not to look grainy or noisy. Bottom line is a single dog that can stay reasonably still does work. A group of dogs is right out. It looks like I need to have a shutter speed around 1/250 or 1/320, and an F-stop in the sub-6.3 range. Not gonna happen.
I've been experimenting with using an off-camera flash to help fill in (currently limited by a 5' cord), but I'm back to unacceptable shadows (even with a diffuser, bouncing), and odd colors and noise that might be just from having to do so much compensation in post. Another problem is my low-budget backdrop that consists of a canvas drop cloth dyed with a double dose of Ritt dye. It's gray, and doesn't absorb shadow at all.
Well, ignore my whining. I remembered I have another PC cord, so I ran both handle flashes with difusers and got some better material at the fabric store. I just finished our first test job with the setup and it worked fine. It was interesting though. Two Jack Russell Terrier mixes and their litter of 6 puppies. Can you say high energy? :