Patellar luxation in dogs and cats: signs, grades and care

Patellar luxation means a dog's kneecap slips out of the groove that should guide it at the front of the knee. It may move in and out or remain displaced.

The problem is usually linked to abnormal development and alignment of the hindlimb rather than the kneecap alone. Repeated slipping can damage cartilage and contribute to pain or osteoarthritis. [1]

A medial luxation moves towards the inside of the leg, while a lateral luxation moves towards the outside. Medial displacement is especially familiar in small dogs, but either direction can occur.

Direction is only part of the diagnosis. The grade, bone alignment, depth of the groove, other knee disease and the dog's clinical signs all influence what the finding means. [1]

Most canine patellar luxation develops because several bones and soft tissues grow out of alignment, allowing the kneecap to leave its groove. Inherited susceptibility and body shape can contribute.

A normal kneecap can also dislocate after substantial trauma, but that is a different clinical context. Developmental disease is not normally explained by one jump, walk or handling mistake. [1]

Yes. One or both knees may be affected, sometimes at different grades. Bilateral disease can make the gait look generally unusual rather than producing one clearly lame leg.

Both knees are therefore checked during an orthopaedic examination. Symptoms, grade and associated deformity can still be different on each side, so treatment decisions are made per joint and per dog. [2]

Signs range from none to an occasional skip, persistent limping, stiffness or an unusual crouched gait. A dog may briefly carry a hind leg, then use it normally again when the kneecap returns.

More severe displacement can interfere with straightening the knee and normal walking. The pattern suggests a knee problem but cannot identify the grade or rule out cruciate and hip disease. [1]

When the kneecap slips out, a dog may lift the leg because the knee cannot move normally. The leg can look normal again after the patella returns to its groove.

An intermittent skip is characteristic but not unique to patellar luxation. A video can help the vet see a brief event that does not occur in the consulting room. [3]

Yes. Mild patellar luxation may be found during a routine examination before an owner notices any problem. The absence of obvious pain does not tell the vet whether the kneecap is stable.

An incidental low-grade finding does not automatically require surgery. Its importance depends on clinical signs, progression, knee structure, age and other joint disease. [1]

Yes. Repeated displacement creates abnormal rubbing and loading in the knee, which can damage cartilage and contribute to osteoarthritis. Pain may become more persistent as joint changes advance.

The X-ray appearance and the dog's comfort do not always match exactly. Long-term assessment follows mobility, muscle and daily function as well as structural changes. [4]

Sudden inability to bear weight, severe pain, major swelling, a visibly deformed leg, an open wound or significant trauma needs urgent veterinary assessment. A familiar skipping pattern should not be assumed to explain a dramatic change.

Fracture, ligament injury, traumatic dislocation and infection can produce acute lameness. A chronic intermittent skip still deserves a routine examination because early signs can become normalised. [3]

The diagnosis is usually made by feeling how the kneecap moves while assessing the dog's gait, pain, knee stability and hindlimb alignment. Each knee is examined and graded.

Imaging adds information about bone shape, osteoarthritis and other disease. The clinical decision uses the whole dog rather than the grade alone. [3]

The grade describes how easily the kneecap leaves its groove, whether it returns and how persistently it remains displaced. The scale runs from a mild, manually movable patella to permanent displacement with marked deformity.

Grade supports communication and planning, but it is not a pain score. Symptoms, age, arthritis, bone alignment and other knee problems also affect management. [1]

At grade 1, the kneecap normally sits in its groove but can be moved out during examination and returns by itself. Many dogs have few or no obvious signs.

The finding still belongs in the dog's record and breeding discussion. Monitoring is reasonable when the dog is comfortable, while new limping or progression changes the clinical question. [1]

At grade 2, the kneecap can slip out by itself or during examination and may stay displaced until the leg changes position or it is replaced. Intermittent skipping is common.

Dogs with the same grade can differ in pain and progression. Surgery is not decided by the number alone; frequency, cartilage damage, age and limb alignment matter too. [1]

At grade 3 the kneecap is displaced most of the time but can still be replaced manually; at grade 4 it remains permanently displaced and cannot be replaced. Limb deformity is usually more important at these grades.

Persistent displacement can interfere with walking and joint development. Specialist imaging and surgical discussion are common, but the final plan still accounts for health, symptoms and realistic benefit. [1]

X-rays show the kneecap's position, osteoarthritis and major changes in the femur or tibia. CT can map complex three-dimensional deformity when precise bone correction is being planned.

Imaging complements palpation rather than replacing it. The chosen views and need for advanced imaging depend on grade, dog size, other knee disease and the proposed treatment. [3]

Yes. Cranial cruciate ligament disease, meniscal injury, osteoarthritis and angular limb deformity can occur alongside patellar luxation. Another condition may explain a sudden worsening in a previously stable dog.

The examination tests overall knee stability and pain rather than stopping after the kneecap is graded. Additional imaging may be needed when the signs do not fit the expected pattern. [1]

No. A comfortable dog with a mild, stable luxation may be monitored and supported without an operation. Surgery is more often discussed for persistent lameness, progression, higher grades or important deformity.

The grade is only one part of that decision. Age, body size, cartilage damage, other knee disease, anaesthetic risk and the dog's daily function also matter. [1]

An appropriate body condition reduces unnecessary load on the knee, while tailored activity and rehabilitation support muscle and controlled joint use. These measures can improve comfort but do not straighten the underlying anatomy.

The useful programme changes with symptoms and any operation, so there is no universal exercise schedule. Sudden deterioration deserves reassessment rather than simply reducing activity indefinitely. [1]

Surgery aims to keep the kneecap tracking in its groove and correct the forces pulling it out. A combination of soft-tissue balancing, deepening the groove, moving the tendon attachment or correcting bone alignment may be used.

The combination depends on the individual anatomy rather than the grade alone. A surgeon explains the expected benefit, recovery demands and complications for the proposed procedures. [3]

Yes. Correcting kneecap tracking can improve function, but it cannot restore cartilage already lost to osteoarthritis. Some dogs have residual lameness, recurrent luxation or another knee problem.

Follow-up checks assess healing and whether the kneecap remains stable. Long-term weight, muscle and pain care may still be useful even after a successful correction. [2]

Many dogs with mild disease remain comfortable, while appropriately selected surgery can improve function in more affected knees. Outlook varies with grade, deformity, arthritis, other joint disease and response to care.

A published success percentage cannot predict one dog. Useful follow-up focuses on comfortable walking, muscle, activity and whether the kneecap stays stable over time. [3]

Yes. Developmental patellar luxation has an inherited component in dogs, so an affected dog's result and family history are relevant to breeding decisions. Surgery improves anatomy but does not remove inherited risk.

Breed-club schemes and veterinary advice can guide screening. A responsible decision also considers other health tests, temperament and genetic diversity rather than one knee finding in isolation. [3]

Yes. A cat's kneecap can slip to the inside or outside of its groove, although the condition is encountered less often than in dogs. It may be developmental or associated with trauma.

Some cats show little, while others develop skipping, lameness or difficulty jumping. The significance depends on stability, pain, limb alignment and other injuries. [1]

A cat may intermittently lift a hind leg, skip, limp, jump less or move with a crouched gait. More severe displacement can make the leg difficult to use normally.

Cats often hide pain, so reduced play, grooming or access to favourite places can matter. These signs are not specific and can also reflect hip, spine, paw or ligament disease. [1]

Yes. A mild or stable luxation may be discovered during examination or imaging for another reason. An incidental finding does not automatically explain every mobility change or require an operation.

The vet considers whether the knee is painful, how easily the kneecap moves, and whether arthritis or another injury is present. Monitoring can be appropriate for a comfortable cat. [1]

Either is possible. Abnormal limb development can make a cat's kneecap unstable, while a strong injury can disrupt a previously normal knee. The history and associated damage help distinguish them.

Sudden severe lameness after trauma needs prompt assessment because fractures, hip injury and ligament damage may accompany or mimic a displaced patella. [1]

The vet feels the kneecap and knee through movement, compares both sides and assesses gait, pain and limb alignment. The same four-grade concept used in dogs describes stability and reducibility.

Radiographs can show bone alignment, arthritis and other injury. A frightened or tense cat may need careful handling or sedation for a reliable examination and useful images. [1]

A comfortable cat with mild, stable disease may be monitored with weight and mobility support, while persistent pain, lameness or unstable higher-grade disease can lead to a surgical discussion.

Management is individual because feline activity, other injuries, bone alignment and anaesthetic health vary. Pain medicine must be selected specifically for the cat by a vet. [1]

Surgery aims to restore kneecap tracking by balancing soft tissues, reshaping the groove, moving the tendon attachment or correcting bone deformity. The required combination depends on the individual knee.

Cats also need a recovery plan that limits unsafe jumping while preserving comfort and muscle. The surgeon sets this around the operation and healing checks rather than a universal timetable. [1]

Sudden inability to use the leg, severe pain, major swelling, a deformed limb or trauma needs urgent veterinary assessment. Stable intermittent signs still merit an appointment rather than being dismissed as clumsiness.

Many mildly affected cats function well, and selected cats improve after surgery. Outlook depends on grade, deformity, arthritis, other injuries and response, so one published case series cannot predict an individual cat. [1]