The patella — the kneecap — normally sits in a groove at the end of the femur and slides up and down as the leg bends. In a luxating patella, it slips out of that groove.
It is one of the most common orthopaedic conditions in small breeds, and it is usually developmental rather than traumatic.
The characteristic sign
A dog trots along normally, then suddenly hops for a few strides with one back leg held up, then puts it down and carries on as though nothing happened.
What is happening: the kneecap has slipped out, the leg cannot extend, and the dog holds it up until it slips back — often with a small kick or a stretch backwards.
Other signs:
- Intermittent lameness that comes and goes
- A clicking or popping from the knee
- Sitting with the leg out to the side
- Reluctance to jump
- In more severe grades, a bow-legged or crouched stance
- Stiffness after rest
- With time, arthritis and persistent lameness
Grades
Vets grade it from one to four, and the grade determines the approach.
Grade 1. The patella can be pushed out manually but returns immediately on its own. Often an incidental finding. Usually no treatment.
Grade 2. Luxates occasionally during normal movement and returns spontaneously or with extension of the leg. This is the classic skipping presentation. Managed conservatively or surgically depending on frequency and discomfort.
Grade 3. Luxated most of the time, can be pushed back but re-luxates. Usually needs surgery.
Grade 4. Permanently luxated and cannot be replaced manually. The dog often has an abnormal, crouched gait. Needs surgery, and the bone deformity is typically more significant.
Who gets it
Small and toy breeds overwhelmingly: Yorkshire Terriers, Chihuahuas, Pomeranians, Toy and Miniature Poodles, Jack Russells, Boston Terriers, Bichons, Cavaliers, French Bulldogs.
It also occurs in larger breeds, where it is often associated with more significant limb deformity.
It is frequently bilateral — both knees — and there is a strong hereditary component, which is why breeders of at-risk breeds should have dogs assessed and graded.
Diagnosis
Physical examination, feeling the patella move as the leg is flexed and extended. Grading is done by hand and takes a minute.
X-rays assess the alignment of the limb, the depth of the groove and the degree of arthritis. For surgical planning, imaging matters.
Treatment
Conservative management suits grade 1 and many grade 2 dogs, particularly those who skip occasionally and are otherwise comfortable:
- Weight control. The single biggest factor. Every extra kilogram increases the load on an unstable joint
- Controlled, consistent exercise to build the muscle that stabilises the knee — regular moderate walking rather than sporadic bursts
- Avoid jumping off furniture and out of cars. Ramps help
- Non-slip flooring. Slipping on hard floors is a frequent trigger
- Physiotherapy and hydrotherapy, which are genuinely useful and underused
- Pain relief during flare-ups, from your vet
- Joint supplements, with the usual caveat that the evidence is mixed and they are an adjunct rather than a treatment
Surgery for grades 3 and 4, and for grade 2 dogs who are frequently lame or in pain.
Procedures typically combine: deepening the groove (trochleoplasty), moving the attachment point of the patellar tendon (tibial tuberosity transposition), and tightening or releasing the soft tissues either side.
Outcomes are generally good, particularly when done before significant arthritis develops. Recovery involves six to eight weeks of restricted exercise and a structured rehabilitation programme.
What helps at home
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Non-slip flooring is the cheapest intervention with the most immediate effect. Runners along the routes your dog uses most.
Ramps or steps to the sofa and bed, and for the car. Introduce them with food so they are actually used.
A supportive bed with a low entry, so getting up does not require a scramble.
Bedsure Orthopedic Dog Bed
Firm foam and a low step-in height. For a small dog with an unstable knee, climbing out of a soft collapsed bed is exactly the awkward twisting movement that triggers a luxation.
Keep them lean. For a 5kg dog, half a kilo is ten percent of body weight. Small dogs are easy to over-treat and the margin is tight.
Outward Hound Fun Feeder Slo Bowl
A measured, reduced portion that takes ten minutes rather than twenty seconds. Weight control is the main treatment available to you between appointments, and making a smaller meal feel bigger is most of how it is sustained.
Short nails. Overlong nails change how the foot loads and reduce traction, which matters more when a joint is already unstable.
Consistent moderate exercise, not a sedentary week followed by a long walk.
When to see a vet
- The first time you notice the skip. Early grading gives you a baseline
- If the skipping becomes more frequent
- If your dog is lame for more than a day or two
- If they hold the leg up persistently
- If there is obvious pain
- At the annual check, ask for the patellas to be assessed if your dog is a predisposed breed
The broader point
A grade 1 or 2 luxating patella in a lean, fit, small dog is frequently a lifelong non-event. The same joint in an overweight dog who jumps off the back of the sofa onto laminate several times a day becomes arthritic, painful and surgical.
The genetics are not yours to change. The weight, the flooring and the furniture are.
