Patellar Luxation – Croney Research Group

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What is Canine Patellar Luxation?

Patellar luxation, also called luxating patellas, is when the kneecap is dislocated or “pops out” of its normal position. It can affect either one or both of the hind legs. The kneecap can move toward the inside of the leg (medial patellar luxation; MPL) or the outside of the leg (lateral patellar luxation; LPL). MPL is more common and it tends to occur in smaller dogs. LPL is usually only seen in larger dogs.

What causes Canine Patellar Luxation?

Patellar luxation is hereditary, and more common in small and toy breed dogs (although some larger breeds are also at risk). In rare cases, trauma can be the cause of patellar luxation. Obesity is not considered a cause, but it can exascerbate the condition.

What are Signs of Canine Patellar Luxation?

Dogs with patellar luxation experience pain and lameness and may limp or lift their hind legs when walking or running. The limp may come and go. You may also notice a “bow-legged” stance. Dogs with patellar luxation may also cry out in pain, avoid exercise, or be unable to jump. Dogs may also develop arthritis or other knee and leg injuries.

How is Patellar Luxation Diagnosed?

Patellar luxation can be diagnosed by any veterinarian. Dogs should be at least 12 months of age for a definitive diagnosis. Radiographs (x-rays) are not required. During a physical exam, your veterinarian will assign a grade of I (less severe) to IV (more severe), describing the level of movement/displacement of the kneecap.

OFA (Orthopedic Foundation for Animals): Dogs can be given a definitive assessment if they are at least 12 months of age. We strongly encourage all breeders to register their results with OFA.

Is there treatment for Patellar Luxation?

For less severe cases, anti-inflammatory medications may be helpful. Weight loss and exercise restriction may also be recommended. However, for many dogs, surgery will be recommended to give your dog the best chance of reducing pain and further injury. Surgery for patellar luxation has a generally good success rate and should be performed as soon after recommendation as possible.

How can I help the dogs in my breeding program?

Patellar luxation is not considered preventable. Keep your dogs at a healthy weight and body condition to prevent the development of arthritis.

Screen your breeding dogs for patellar luxation, especially breeds at higher risk. Your veterinarian can help you make breeding decisions based on your dog’s test results. The goal is to reduce the risk of passing on this condition to puppies and your future breeding dogs.

Talk to your veterinarian at the first signs of lameness or limping. Surgery is most successful when performed before arthritis develops.

Breeds most commonly affected by patellar luxation

  • Boston Terrier
  • Yorkshire Terrier
  • Maltese
  • Bichon Frise
  • Pug
  • Chihuahua
  • Pomeranian
  • Toy Poodle
  • Great Pyrenees
  • Akita
Small and toy breeds are more likely to be impacted by patellar luxation. However, cases are increasing in medium and large breed dogs.

Information about OFA screening: ofa.org/diseases/patellar-luxation/

Canine Patellar Luxation statistics by breed (OFA): ofa.org/chic-programs/browse-by-breed/

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Topic(s): Bare Bones Basics, Breeder Resource, Health, Reproductive Healthcare, Veterinary Care