Our dog's groin to ground measurement was 19 inches. We ordered the smaller struts, but recently ordered the larger struts and are much happier with the fit. Our dog seems to have longer legs in the back though. He is a doberman mix. Hope this helps.

We have had our walkin' wheels for about 3 weeks now and have been slowly adjusting and acclimating Rocky to the wheels. I'm proud to say that he is doing quite well this past week and his spirits have soared as a result of the use of the wheels and being able to go on a walk around the block again....