Patellar Luxation

What It Is

Patellar luxation—basically, a dislocating kneecap—is one of the most common orthopedic issues in small and toy breed dogs. The patella (kneecap) sits in a groove on the femur and normally glides up and down as the knee bends. In dogs with luxating patellas, that groove is too shallow or the ligaments are too loose, so the kneecap slips out, usually toward the inside of the leg (medial luxation). It’s graded on a scale from 1 to 4: Grade 1 means it only pops out when manually pushed and slides back on its own—often causes no issues. Grade 4 is severe: the kneecap is permanently out of place, the leg is deformed, and the dog can’t straighten the joint. It’s usually a congenital issue, meaning dogs are born with the anatomical flaws, even if symptoms don’t show up until later.

Symptoms to Watch For

You might not notice anything off in mild cases. But signs to keep an eye on include occasional “skipping” when running—your dog suddenly lifts one back leg and hops for a few steps before putting it down again. That’s the kneecap slipping out and then popping back in. Over time, you might see reluctance to jump, stiffness after resting, or even crouched hind legs. In severe cases, your dog walks with a bowlegged stance or holds the leg up constantly. Pain isn’t always obvious, but chronic luxation leads to arthritis, and by middle age, some dogs develop significant lameness or secondary injuries like torn ACLs. If you see consistent limping or your dog avoids stairs or jumping into the car, get it checked.

Diagnosis

Your vet diagnoses this with a physical exam—manipulating the knee to see if the patella slips out and how easily it returns. They’ll assign a grade based on that. X-rays aren’t always needed for diagnosis but can help assess the severity of bone deformities, especially if surgery is on the table. In some cases, especially if the dog is showing pain but the luxation isn’t obvious, your vet might refer you to a veterinary orthopedist. The cost for an initial exam and diagnosis runs $100–$200, depending on your area and whether imaging is included.

Treatment Options

For Grade 1 and sometimes 2, no treatment is needed if your dog isn’t showing symptoms. You just monitor. For painful or higher-grade cases, especially Grade 3 and 4, surgery is usually recommended. The procedure typically involves deepening the femoral groove, moving the tibial crest (where the tendon attaches), and tightening soft tissues. Success rates are good—around 90% of dogs improve significantly, though some may still develop arthritis over time. Recovery takes 6–8 weeks of strict rest. Surgery runs $1,500–$4,000 per knee, depending on complexity and location. If both knees are affected (common), it’s often done one at a time to keep your dog mobile during recovery. Physical therapy can help post-op and might cost $50–$100 per session.

Prevention and Screening

You can’t prevent the genetics, but you can avoid making it worse. Keep your dog lean—extra weight puts more stress on those tiny joints. Avoid high-impact activities like jumping off furniture; use ramps or steps. And if you’re getting a puppy from a breed at risk, make sure the breeder screens parent dogs. Reputable breeders have their dogs evaluated by the Orthopedic Foundation for Animals (OFA), which requires dogs to be at least 12 months old and x-rayed. A “clear” OFA patella rating means both parents are less likely to pass it on. Skip breeders who don’t provide health clearances—this condition is that common and that avoidable with responsible breeding.

Breeds Most at Risk

Patellar luxation pops up in at least 77 breeds, but it’s especially widespread in small dogs. Toy breeds are hit hardest—19 of them are high-risk, including Chihuahuas, Bichon Frises, and Yorkshire Terriers. Terriers are next with 17 affected breeds like Boston Terriers and Cairn Terriers. The issue also shows up in breeds from the Non-Sporting Group (think Bulldogs and French Bulldogs) and Foundation Stock breeds like the Biewer Terrier. Even larger breeds can be affected, but it’s far less common. If you’re eyeing a breed from the Toy or Terrier group, assume luxating patellas are on the table. Ask breeders directly about OFA testing and whether any puppies in recent litters showed signs. It’s not a death sentence—plenty of dogs live full, happy lives with mild cases—but it’s something you should go into with your eyes open.