This dog is like Dolly. Her hind legs are straight and don't bend at the knee. (Dolly only has one hind leg, but it is straight like this.)
This is the first picture or video I've seen of a dog with straight legs in a wheelchair. Her name is Rita. She seems to be using the cart just fine.
https://www.bbc.com/news/av/uk-england-devon-60622672
Wheelchair dog with hind legs that don't bend
Re: Wheelchair dog with hind legs that don't bend
Interesting!