Poor little one!! Here are the first things I check: can I touch and move every bone – checking for a fracture. How much rotation to the inside is there of the lower leg on the upper leg – quick test for torn cruciate ligaments (ACL – football player injury). Are all 5 muscular components of the Achilles tendon still there – can have a torn ligament at the hock/heal. The next thing is to check that the head of the femur (leg bone) is well seated in the pelvis – need to do radiographs (x-rays). The x-rays will also tell if there is loss of bone at the head of the femur – this is a progressive loss of bone in the leg bone due to damage to the tiny little blood vessel in the socket joint that connects the pelvis to the femur – called Legg-Perthes- Calve’s disease. I also check the knee (stifle) joint while I’m taking radiographs to look for the “fat pad” sign in the knee that supports a torn cruciate ligament. If all of those are ok, I will adjust (veterinary spinal manipulation thereapy) the cutie, use therapeutic laser on the sore part of the back, and I may prescribe some pain meds or anti-inflammatories. One tiny little fall like that can have many different repercussions, several of which can become surgical cases. The sooner you get the small one checked out, the better.