Patella Luxation (knees)
Patella Luxation is common in ALL toy breeds. In the Shorkie the luxation can be thought to be congenital but whether its congential or not is unknown for certain and can not be 100% proven. In research study it's shown patella luxation can be caused due to a injury and its diagnosed in 7% of (toy breed) puppies.
Even with studies from the OFA if you have both parents OFA certified still 35% of those dogs can show up with patella problems. Its just no way to totally prevent it from happening. Studies show it seems to be Polygentic meaning it can possible be carried down the bloodlines and may never show up until you breed together the right combination. You can have two parents who tested clear on the OFA test. Then if you breed those two and if its the right combination (meaning both dogs are carriers of Patella Luxation, but never show any signs of Patella Luxation, meaning it can be down in both dogs lines-genetics) it can then show up in the offspring.. That's the reason it cannot be prevented and why we cannot guarantee against it or warranty in it our breeding program. We do ouor very best to prevent this but this is one of those things that is in God's hands completely.
This is a TOY BREED issue not just in the Shorkies