Nicole,

I use what I know. I am a dog groomer. I find that dogs that are used to being groomed do pretty well at moderate heights while staying relaxed. I will put a prop (chair, basket, bench) on top of a 24" or so table. I run the background on top of the table to hide it and the added height tends to keep the pet in place. Too low, and they will be more likely to jump right off.

Of course we're on the floor too. There you just have too wait them out to get the shot.

Doug