Patellar luxation — where the kneecap slips out of its groove — is among the most common orthopaedic conditions in small dogs, ranging from incidental finding to painful disability requiring surgical correction.
The welfare impact of patellar luxation varies enormously by grade. Grade I and II dogs may be asymptomatic or only intermittently lame; Grade III and IV dogs experience chronic pain and functional disability from an unstable joint with chronic inflammation and cartilage damage. The correlation between patellar luxation and secondary cruciate disease — itself a major welfare problem — means that untreated high-grade luxation causes compounding welfare harm over time. Surgical correction in appropriate candidates produces excellent welfare outcomes with a high proportion of dogs returning to full function. The primary welfare issue is accurate grading to identify which dogs require surgery, and prompt referral to avoid allowing progressive joint damage.