What is a Luxating Patella in a Dog?

Ziggy and Roxy, our February 2026 Dogs of the Month. Two Cavoodles who both have Luxating Patella's.

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What is a Luxating Patella?

When a dog has a luxating patella, this means that their kneecap (the patella) slips out of its normal position in the thigh bone (femur). This causes the knee to dislocate (luxate) sideways. The term “luxating patella” simply means the kneecap dislocates out of place.
There are two types of luxating patella:
MPL – Medial Patellar Luxation
This is where the kneecap moves inward out of position. This is the most common type of patellar luxation, and symptoms are usually seen earlier in a dog’s life. It is most commonly seen in small dog breeds.
LPL – Lateral Patellar Luxation
This is where the kneecap moves outward from its normal position. This is less common and is often seen in medium to large dog breeds. It is also more common in dogs that suffer from hip dysplasia.
A knee affected by a luxating patella is more likely to develop arthritis earlier in life due to consistent rubbing on the joint cartilage.

What causes a Luxating Patella?

In most cases, a luxating patella is a hereditary condition passed down from breeding parents. However, it can also develop over time or be caused by a degenerative condition.
It’s important to ensure that the medical history of breeding parents is known, to help prevent luxating patellas from being passed on to future litters.

What happens when a patella luxates?

In mild cases, signs of a luxating patella may remain asymptomatic, and dogs are often able to pop their kneecap back into place on their own, sometimes without the owner even noticing.
A common sign is a dog walking with a “skip” in their step. They may briefly hold up the affected leg, kick it out, or shake it. If they quickly return to normal walking, it usually means the patella has slipped back into place on its own.
As a dog ages with a luxating patella, they may become increasingly lame in the affected leg. This is due to ongoing cartilage wear, which can lead to discomfort and arthritis.
If a dog needs help getting the patella back into place, they may cry out in pain and lick at the knee joint. It’s best not to handle the leg, as dogs can often correct it themselves. However, if the issue persists or the dog becomes distressed, veterinary attention should be sought as soon as possible.

How is a Luxating Patella diagnosed?

During a physical examination, your vet can diagnose a luxating patella and assign it a grade. Luxating patellas are graded from 1 to 4 to determine severity, guide treatment, and monitor progression over time.

• Grade 1: Mild and unlikely to significantly impact day-to-day life
  
• Grade 4: Severe, painful, and likely to require surgery
  

Treatment for Luxating Patellas

Grade 1–2:
These cases often don’t require major intervention. Management includes maintaining a healthy weight and avoiding activities that involve sudden stopping, sharp turns, or spinning. Dogs may also benefit from physiotherapy or anti-inflammatory medication if discomfort is present.
Grade 3–4 (or frequent Grade 1–2 cases):
Surgery is usually recommended. This helps realign the patella, reduce pain, and minimise the risk of early-onset arthritis, especially in younger dogs.