Luxating patella in dogs (explained by a vet)

If your dog skips or hops intermittently you might be curious about whether they have luxating patella. 

This condition is common in small and toy breeds specifically but it’s not unusual for larger dogs to experience ‘floating kneecap’. For many dogs, it goes undiagnosed until it becomes severe and, because it comes and goes it may not bother your dog initially.

In this blog, Zooomy’s vet Humphrey will explain what luxating patella is, the signs to look for, and how to treat it. Read on to get clued up and help your dog stay comfortable. 

 

What is a luxating patella?

In simple terms, a luxating patella in dogs is when the patella (the kneecap) pops out of place. It’s commonly referred to as ‘floating kneecap’ or a ‘trick knee’ and it means your dog’s kneecap temporarily slips out of the groove it’s supposed to sit in.

The kneecap is a small bone inside the big tendon that links the thigh muscle above the knee with the shin bone below.  This tendon pulls the dog's leg straight as the thigh muscle contracts and the patella enables the tendon to slide easily over the front of the knee.

The kneecap sits within a groove on the front of the knee joint which is lined with cartilage and lubricated by synovial fluid. In a healthy dog, when the dog’s thigh muscle contracts, the tendon moves over the knee joint and the lubrication and patellar groove keep the kneecap in place on the front of the knee.

In dogs who suffer from luxating patella, they often have bent or bowed legs or a shallow patella groove - and so when the quadriceps contracts and pulls against the front of the tibia, the patella is pulled out of that groove. And that's what a luxation is - a dislocation of the patella from its groove. 

Depending on the extent of the issue, the patella can pop out momentarily or in the worst cases become stuck and require manual replacement which causes the leg to be stuck straight out which can be distressing for the dog and owner - more on grades below.

But first, let’s take a look at the signs of luxating patella. 

Signs of luxating patella

Dogs with a luxating patella typically show one of more of the following signs:

• Intermittent hopping or skipping on the back legs

• Abnormal or variable gait

• Limping or temporary lameness

• A clicking sound when the knee bends or straightens

• Shallow extension of the legs when walking or running

• Odd sitting and sleep positions where the legs point outwards

The most common signs of a luxating patella are a short skip or hopping like movement that goes away almost as quickly as it appeared. Perhaps the dog is running for a ball, skips for a few steps, then continues running normally. Or they’re walking along normally, hop on their back legs for a few steps, and return to normal. 

The hopping and skipping movements happen because the patella has slipped out of the groove and it feels uncomfortable - a bit like us when we feel something pull out of place in our bodies.  Then after a bit, once the dog’s taken the strain off the tendon, the patella will pop back in.

In dogs with more advanced patella luxation, you may see an abnormal gait. This looks like a dog whose legs bow or aren’t symmetrical in stance. Sometimes you’ll see one side of the dog’s body is more muscly than the other, as they’ve been compensating by bearing more weight on one side. 

Causes of luxating patella

Patella luxation is generally genetic and common in dogs who’ve been bred from dogs with a bow legged conformation. It can also develop in dogs after a trauma to the knee - for example a dog who’s suffered a cruciate ligament injury. 

 

Breeds it commonly appears in

Luxating patella is more common in small breeds of dogs such as Yorkshire Terriers, Pomeranians, Chihuahuas, Miniature Poodles and other toy breeds. It is also commonly seen in bulldogs and larger breeds like Labradors, Boxers, Great Danes and St Bernards. 

At what age does luxating patella start?

Luxating patella can occur at any age. Sometimes the signs present at a relatively young age but are missed because they’re intermittent. It’s often not until the occurrences of luxation become more frequent or lameness sets in before an owner realises there’s a problem. 

Because dogs with low grade luxating patella can still be very active and aren’t whining or crying in pain, it can be easy to miss. This is also hindered by people saying the hopping or skipping is normal in certain breeds (like cockapoos for example), when in reality, it’s more that it’s common for these breeds to have luxating patella. 

Should you walk a dog with luxating patella?

Yes, healthy weight helps. Avoid high impact exercise - games like fetch put strain on joints, and don’t mistake your dog’s willingness to keep going to mean they’re ok. When a dog’s in a state of high arousal, adrenaline can mask pain and discomfort. This means your dog may continue to chase a ball or run around frantically with their friends - despite there being underlying discomfort. 

 

Can a dog live with luxating patella? 

Yes -  a dog can absolutely live with luxating patella and many remain very active despite the condition. It’s worth noting that a dog with patellar luxation is more prone to developing osteoarthritis and cranial cruciate ligament disease. 

The quality of life and comfort of a dog with patella luxation is highly dependent on the grade of luxation your dog is experiencing.

Patella luxation grading

• Grade 1: The knee cap can be luxated with pressure but generally stays within the groove. 

• Grade 2: The knee cap occasionally luxates sporadically during normal movement like running or walking. 

• Grade 3: The knee cap is always out of the groove but can be manually manipulated back into place. 

• Grade 4: The knee cap is permanently out of the groove and cannot be manipulated back into place. 

How to fix luxating patella

Surgery is an option to make the patella groove deeper so the kneecap doesn’t pop out. It’s a pretty severe orthopedic surgery with a strict recovery period. There are a few different surgical options but it’s generally an expensive surgery reserved for dogs with high grade luxations. 

For low grade luxations and for older dogs, conservative management is often chosen. Maintaining a healthy weight relieves pressure on the joints - and making adaptations around the home and to exercise can help a great deal. 

Conservative management of luxating patella:

• Use rugs, carpet and non-slip mats to reduce slipping and relieve impact

• Stick to low impact exercise and gentle terrains

• Use a ramp for the car or lift your dog in and out to prevent jumping

• Use a stair gate to limit access to stairs

• Maintain a healthy weight to reduce pressure on joints

• Introduce joint support like hyaluronic acid to aid lubrication

• See your vet to discuss pain relief and/or laser therapy

• Consider physio, hydrotherapy, and canine massage

• Heated beds or mats can help soothe inflammation and pain

Starting a joint support supplement is a good idea since luxating patella can often lead to the onset of arthritis. The frequent luxation of the kneecap wears down joint cartilage which can lead to progressive joint degeneration.

While arthritis and luxating patella are irreversible, being proactive about supporting your dog’s joints can help slow progression. This is best combined with pain relief from your vet. 

Zooomy is a vet developed hyaluronic acid joint supplement that’s gentle on tummies and lubricating for joints. With zero fats, proteins and sugars, it’s an oral solution that’s easy to give and safe to give alongside medication. 

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