Ollie is a 4 year old rescue with a torn acl. We had been struggling with it for almost 3 months when we decided investing in a brace was far less costly than the surgery we were facing. I wish we had purchased this brace right away – it helps SO much! The first time we used the brace he walked normally! We keep it on him for walks and yard time and after using it for only 10 days I no longer expect to have to get his acl repaired surgically. He has improved dramatically. I highly recommend this product. Great customer service – came in 4 days. Also, I was pleasantly surprised that despite Ollie having a 67lb body on tiny little legs the sizing guide worked out and the medium fits perfectly.