"When I saw this product online, I was afraid the straps might be too wide for my little 20# French Bulldog but thought it was still worth a try. The item arrived very quickly (thanks, Petco.com). The straps would be better if they were made out of say a Mountain lead/collar material (rounded woven nylon or cotton). My dog didn't want to walk in it at first but with a trail of food on the floor he overcame that fairly quickly. He still isn't comfortable in it enough to eliminate with it on (though it's just the first day).
It's also a fine line between giving him enough slack to squat but keeping enough tension for the straps not to slip down his legs. He's also a little dickens who still will scamper in the yard even though he's losing use of his hind legs, so that makes it hard to keep up with him! I think I may just drop the lead and let him run out of it when he does that, but I'm afraid it will trip him, so we'll see about that idea.
Anyway, I would still recommend the Bottom's UP leash for medium to large size dogs having trouble with their hind ends. I may leave another comment after having more experience with it and my smaller dog (don't tell HIM he's small!)"