A slipping kneecap, medically patellar luxation, is one of the most common orthopaedic problems in small breeds, Cavaliers included. Unlike the heart and the spinal cord, this condition is often first noticed at home, and by a very recognisable movement.
This article explains what happens in the knee, how it is recognised, how it is graded and when surgery is needed.
What patellar luxation is
The patella is the kneecap. It glides in a groove on the thigh bone and thereby keeps the tendon in the right place with every step.
In patellar luxation the kneecap slips out of that groove, most often towards the inner side of the leg. The reason is usually a shallow groove or a slightly bent axis of the leg, that is the build the dog was born with, not an injury.
That is why the problem most often appears early, in young dogs, and why it is passed on to offspring.
What it looks like when the kneecap slips
The sign is so characteristic that owners describe it almost identically every time:
- while running, the dog suddenly lifts a hind leg and carries on hopping on three legs
- after a few steps it puts the leg down and carries on as if nothing had happened
- sometimes a faint click can be heard
- the dog does not yelp and does not appear to be in pain
Precisely because the dog carries on normally, this sign is often overlooked and put down to clumsiness. If it happens repeatedly, it is worth mentioning to the vet at the next visit.
Grades 1 to 4
The vet assesses the knee by hand, without any equipment, and places it in one of four grades:
- Grade 1: the kneecap can be pushed out of the groove with a finger but returns on its own immediately. The dog has no complaints at all.
- Grade 2: the kneecap slips out on its own from time to time and returns by itself or when the dog stretches the leg. This is the grade at which the hopping on three legs appears.
- Grade 3: the kneecap is out of place most of the time but can be put back by hand. The dog walks with a bent leg and limps more often.
- Grade 4: the kneecap is permanently out of place and cannot be put back. The leg is bent and the dog barely uses it.
In Cavaliers grade 1 or 2 is most often found, and in most cases it does not call for surgery.
When surgery is needed
The decision depends not only on the grade but also on how much the dog is troubled by it.
Grade 1 is not operated on. Grade 2 is operated on only if the dog limps often or if the condition worsens from year to year. Grades 3 and 4 almost always call for a surgical solution, because left untreated they lead over time to arthritis and permanent damage to the joint.
Surgery in small breeds gives good results, and recovery takes a few weeks with restricted movement.
What helps without surgery
With the milder grades a great deal can be achieved without a procedure:
- Keeping the weight down. This is the single most important thing. Every extra kilo loads the knee with every step.
- Moderate, regular activity. Walks on the flat strengthen the muscles that hold the knee in place.
- Avoiding jumps from a height. Jumping off the sofa or out of the car is the single worst movement for the knee.
- Non-slip surfaces. Rugs on laminate and tiles reduce sudden movements.
- Trimming the hair between the pads, because long hair slides on a smooth floor.
A ramp or steps up to the sofa and the bed are a cheap and very effective measure for a dog with a diagnosis.
Why it matters when buying a puppy
Patellar luxation is inherited, so a knee examination is among the pre-mating tests.
The examination is simple, done by hand and takes a minute. The report contains a grade for the left and the right knee separately, along with the date and the dog's details.
A breeder who has a cardiac report and an eye report usually has a knee report too, because it is done in the same visit. If there is none, it is reasonable to ask.
Conclusion
A slipping kneecap in Cavaliers is most often mild and shortens neither life nor its quality. What is worth paying attention to is that hopping on three legs, which looks harmless and is easily missed. In a dog with a diagnosis, keeping the weight down and avoiding jumps from a height do more than any food supplement.
Note: this article is informational and does not replace examination and advice from a veterinarian.
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- Eye problems in Cavaliers: what occurs and how to recognise it
- Ear problems in Cavaliers — why drop ears need more care
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- Cavalier vaccination and deworming: schedule by age
- Living with a Cavalier diagnosed with MVD
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