horselover.. its more than the sway back its called CA . It appears like wobbles or little bit of uncoordinated movement . Don't know when it shows and you can google genetic disease in Egyptian Arabian horses. I have an arab mare SE, good lineage from what I have been told, she is super swayed, and her hind end moves way different from her front end, and its gotten worse as she ages (now 17) . I rescued her , put 300lbs on her and kept her from being someones brood mare. I am still shaking my head that they even bred her , she has many faults.