Your Shih Tzu was running perfectly fine. Then, mid-stride, she suddenly lifted one back leg and hopped on three legs for a few steps then put it down and kept going like nothing happened.

You Googled it, found nothing clear, and decided to wait. It happened again the next day. And the day after.

That strange little hop has a name. And if you don't know about it, it can quietly become something much more serious.

A luxating patella in dogs is a condition where the kneecap the patella slips out of the groove it normally sits in, causing a sudden skip or hop on the back leg. It is one of the most common orthopaedic conditions in small and toy breeds like Shih Tzus, Pomeranians, Chihuahuas, and Maltese, though medium and large dogs can be affected too. Vets classify it from Grade I (mild, kneecap pops back on its own) to Grade IV (permanently out of place). Treatment depends on the grade and ranges from weight management and joint supplements to surgical correction.

Key Takeaways

• A luxating patella means the kneecap keeps slipping out of its groove on the thigh bone it is a structural problem, not a sprain or injury.
• The classic sign is a sudden three-legged hop for a few steps, then the dog walks normally again often repeated during play, running, or turning.
• It is graded I to IV: Grade I is mild and often monitored; Grade II may or may not need surgery; Grade III–IV usually require surgical correction.
• Small and toy breeds like Shih Tzus, Pomeranians, Chihuahuas, Maltese, and Lhasa Apsos are at highest risk though Indian street dog mixes with small-breed ancestry can also develop this.
• Left untreated, higher-grade luxation causes cartilage damage, progressive arthritis, and can eventually trigger a cruciate ligament tear.
• Surgery is highly effective, especially when done before significant joint damage develops. Most dogs return to full activity within 8–12 weeks.
• Keeping your dog lean is the single most controllable factor excess weight accelerates cartilage wear in an already unstable knee.

What Is a Luxating Patella in Dogs?

Luxating patella — also called patellar luxation or a floating kneecap is a condition where the kneecap moves out of the groove it is supposed to sit in. "Luxating" simply means "dislocating" or "moving out of place."

In a normal knee, the patella sits in a channel at the bottom of the thigh bone called the trochlear groove. It glides smoothly up and down in this groove every time the dog bends and straightens its knee. When the anatomy around the groove is off either the groove is too shallow, the leg bones are misaligned, or the soft tissues around the knee pull the kneecap sideways the kneecap can pop out of its track.

According to SpectrumCare, the problem is usually not the kneecap alone. Many affected dogs also have a shallow trochlear groove, abnormal pulling from the quadriceps muscle mechanism, or alignment changes along the femur (thigh bone), tibia (shin bone), or hip that all contribute to the kneecap slipping out.

This condition is developmental and inherited in most cases it is not caused by a single injury or accident. The bones and soft tissues simply didn't grow into exactly the right alignment as the puppy developed. This is why it is so common in small breeds, and why breeding dogs with patellar luxation is generally not recommended.

How the Knee Works — and What Goes Wrong

A dog's knee joint called the stifle connects three bones: the femur (thigh bone), the tibia (shin bone), and the patella (kneecap). The patella sits at the front of the knee in the trochlear groove, a channel that keeps it tracking straight as the leg moves.

Underneath the patella runs the patellar ligament, which connects the large quadriceps muscles of the thigh to the front of the tibia at a bony prominence called the tibial tuberosity. When the quadriceps contract, this ligament pulls on the tibia and straightens the knee. The patella acts like a pulley redirecting the force efficiently.

For this system to work, the tibial tuberosity must sit in the centre of the shin, perfectly aligned with the groove on the femur. When it doesn't because the tibia is slightly rotated, the femur is bowed, or the groove is too shallow the kneecap is pulled sideways rather than straight. Over thousands of steps and jumps, this lateral pulling gradually wears away the inside of the groove, making it even easier for the kneecap to pop out. A vicious cycle begins.

As VCA Animal Hospitals explains, many small dogs learn to compensate by kicking their leg outward, which causes the knee to hyperextend and "snaps" the kneecap back into place. That is exactly what the three-legged hop looks like from the outside.

Medial vs Lateral: The Two Types Explained

The kneecap can dislocate in two directions.

Medial Patellar Luxation (MPL) — The kneecap slips toward the inside of the leg (toward the midline of the body). This is by far the most common type, accounting for roughly 75% of all cases. It is especially common in small and toy breeds. The classic cause is a tibial tuberosity that sits too far medially (inward), causing the patellar ligament to pull the kneecap off track toward the inside of the joint.

Lateral Patellar Luxation (LPL) — The kneecap slips toward the outside of the leg. This is less common overall and is more often seen in large and giant breeds. In large dogs, it tends to develop as a slower-progressing developmental condition, sometimes causing a "knock-kneed" stance where the knees turn inward and the paws pivot outward as the dog walks.

Both forms can affect one or both knees. According to VCA Animal Hospitals, approximately 50% of affected dogs have both knees involved though often one side is worse than the other.

Grading the Luxation: I, II, III, and IV

Vets use a four-grade system to describe how severely the kneecap is dislocating. This grade is the single most important factor in deciding whether surgery is needed.

As SpectrumCare notes, the grade does not always perfectly match how painful a dog appears. Some Grade II dogs are surprisingly comfortable; some Grade II–III dogs seem clearly uncomfortable. Your vet combines the grade with your dog's actual symptoms, activity level, age, body condition, and X-ray findings to make the treatment recommendation.

A critical point: grade can change over time. A dog diagnosed at Grade II can progress to Grade III as the groove wears down further. This is why regular rechecks matter even for mild cases.

What Are the Signs of Luxating Patella in Dogs?

My dog suddenly hops on three legs then walks normally — is that a luxating patella?

Yes, this is the most recognised sign of patellar luxation. The sudden three-legged hop where a dog lifts one back leg mid-stride for a few steps, then puts it back down and continues normally is a near-textbook presentation. It happens when the kneecap slips out during movement and the dog compensates until it snaps back into place.

Watch for these signs in your dog:

• The skip or hop lifts one back leg suddenly, hops 2–5 steps, then continues walking normally
• The "kick-back" dog extends or flicks the leg backward or outward, which snaps the kneecap back into the groove; often happens right after the skip
• Brief non-weight-bearing during a run or play session, the dog suddenly stops putting weight on one back leg, then resumes
• Sudden yelp during play, turning, or jumping the moment the kneecap dislocates can be painful
• Reluctance to jump won't hop onto the sofa, hesitates at the bottom of stairs
• Morning stiffness gets up slowly and is stiff for a minute before loosening up
• Crouched hind-limb posture stands or walks with the back legs slightly bent or "hunched" in more advanced cases
• Knock-kneed or bowlegged stance visible limb deformity in Grade III–IV dogs
• One thigh visibly thinner than the other muscle loss from chronic disuse of the affected leg
• Persistent lameness rather than intermittent skipping a sign of higher-grade disease or a secondary injury like a cruciate ligament tear

See your vet promptly if: the skipping is becoming more frequent, your dog seems painful between episodes, the leg stays up for longer periods, or your dog is unwilling to use stairs or jump. See your vet immediately if your dog is non-weight-bearing for more than a few minutes, cries out repeatedly, or has obvious swelling a concurrent cruciate tear needs to be ruled out.

Which Breeds Are Most Affected?

Patellar luxation has a strong genetic component and is concentrated in specific breeds. According to SpectrumCare and VCA Animal Hospitals, the small and toy breeds at highest risk include:

Toy and small breeds (medial luxation):

• Shih Tzu
• Lhasa Apso
• Pomeranian
• Chihuahua
• Yorkshire Terrier (Yorkie)
• Maltese
• Toy Poodle and Miniature Poodle
• Bichon Frise
• Pekingese
• Cocker Spaniel

Medium and large breeds (can be lateral or medial):

• French Bulldog
• Labrador Retriever (less common but possible)
• German Shepherd Dog
• Great Dane (lateral, developmental)

In India, Shih Tzus, Lhasa Apsos, and Pomeranians are among the most popular small breeds in cities like Mumbai, Pune, Delhi, and Bangalore. All three are prominently on the high-risk list. Many Indian pet parents of these breeds notice the skip around 1–2 years of age and attribute it to a "muscle pull" or "minor sprain" and wait months before seeing a vet. By then, the grade may have advanced and the cartilage may already be damaged.

What Causes Luxating Patella?

Most cases of patellar luxation are developmental and hereditary the abnormal anatomy was there from birth and became more apparent as the puppy grew. There is no single "cause" that a pet parent can control.

Genetic predisposition is the primary driver. The condition runs in family lines. If one or both parents had patellar luxation, the puppies are at higher risk. This is why responsible breeding programs screen for it, and why affected dogs should ideally not be bred.

Limb alignment anomalies often accompany the luxating kneecap rather than being separate causes. These include a shallow trochlear groove, internal or external rotation of the tibia, bowing of the femur, and hip alignment changes. All of these work together to pull the patellar ligament off its straight tracking line.

Body weight and muscle condition do not cause patellar luxation, but they influence how symptomatic it becomes. Extra weight increases force across the already-unstable knee and accelerates cartilage wear. Poor thigh muscle condition offers less support to the joint during movement.

Trauma can cause a healthy patella to luxate acutely, but this is far less common than the developmental form. A dog that suddenly becomes lame after a fall or rough play needs a vet to distinguish between a traumatic luxation and an existing chronic luxation that has been aggravated.

Note for Indian pet parents: This is not caused by playing on marble floors though marble floors make it worse by increasing slipping and instability in a dog that already has a loose kneecap. Non-slip mats are a useful home intervention but do not prevent the underlying condition.

How Is Luxating Patella Diagnosed?

Step 1: Physical Examination and Grading

Your vet will examine your dog's knee by feeling for how easily the kneecap moves out of its groove and whether it returns on its own. This palpation done while gently flexing and extending the knee is what determines the Grade I–IV classification. The vet will also watch your dog walk and trot to assess gait, muscle condition, and leg use.

Step 2: X-Rays

Radiographs of the knee (and often the whole hindlimb) are recommended for most dogs being evaluated for patellar luxation. X-rays can show:

• Degree of arthritis already present
• Limb alignment and any bone deformities
• Signs of a concurrent cruciate ligament injury
• Whether the trochlear groove is visibly shallow or worn

Both knees should be X-rayed, even if only one is symptomatic. Bilateral disease is common, and the asymptomatic side may still be Grade I–II.

Step 3: Advanced Imaging for Complex Cases

For Grade III–IV dogs, large-breed dogs, or cases where bone deformity correction is being considered, a CT scan may be recommended for surgical planning. CT gives a precise 3D view of limb alignment that a standard X-ray cannot fully capture.

Treatment Options: From Monitoring to Surgery

SpectrumCare describes three levels of care. The right level depends on the grade, frequency of symptoms, degree of arthritis, dog's age, and practical factors.

Level 1 — Monitoring, Weight Control, and Symptom Management

Best for: Grade I, mild Grade II, dogs with infrequent skipping, or as a starting point for owners assessing the situation.

This approach does not fix the anatomy, but it manages symptoms and slows deterioration. It includes:

• Weight management — the single most impactful non-surgical intervention. Even modest excess weight measurably increases stress on an unstable kneecap. Ask your vet for a body condition score and a feeding plan.
• Exercise modification — leash walks on even ground, avoiding repeated stairs, jumping, or rough play on slippery surfaces; consistency is better than intensity
• Joint supplements — glucosamine and chondroitin support cartilage health and may reduce discomfort. FLEXADIN FORTE TABLET by Vetoquinol (on Animeal) provides 500mg Glucosamine Hydrochloride, 400mg Chondroitin Sulfate, Omega-3 fatty acids (EPA + DHA), and Devil's Claw as a natural anti-inflammatory all in one palatable chew. The dose for small dogs is ½ chew per day. For longer-term maintenance, FLEXI PLUS TABLET by Venttura (on Animeal) adds Marine Collagen Peptides, Hyaluronic Acid (joint lubrication), MSM, and Boswellia serrata alongside glucosamine and chondroitin — a comprehensive support formula for dogs already diagnosed with joint conditions.
• NSAIDs for pain during flare-ups — anti-inflammatory medication prescribed by your vet as needed; never use human ibuprofen or paracetamol for dogs
• Regular rechecks — every 3–6 months to monitor whether the grade is progressing

Critical: Conservative management does not stop the kneecap from luxating. Arthritis will continue to develop. A dog managed without surgery should be rechecked regularly, because a Grade II that becomes Grade III warrants a fresh conversation about surgical correction.

Level 2 — Surgical Correction

Best for: Symptomatic Grade II dogs, most Grade III dogs, and any dog whose quality of life is affected by frequent lameness or pain.

Surgery is highly effective for patellar luxation, especially when performed before major arthritis develops. According to VCA Animal Hospitals, more than 90% of dog owners report satisfaction with their dog's progress after surgery.

Level 3 — Specialist Reconstruction and Complex Deformity Repair

Best for: Grade IV dogs, severe deformity, large-breed dogs, failed prior surgery, or concurrent cruciate ligament disease.

This involves referral to a board-certified veterinary surgeon for procedures including corrective osteotomy (reshaping the bone), advanced CT-planned repair, and formal rehabilitation. These cases are more intensive and less common but can still yield excellent outcomes in carefully selected patients.

What Does Surgery for Luxating Patella Involve?

Most luxating patella surgery combines two or three procedures performed at the same time:

Trochleoplasty (Groove Deepening) The trochlear groove on the femur is surgically deepened so the kneecap has a proper channel to sit in. There are two techniques trochlear wedge resection and trochlear block recession. Both create a deeper groove that keeps the patella tracking centrally.

Tibial Tuberosity Transposition (TTT) The bony prominence where the patellar ligament attaches on the tibia is cut free and repositioned so it sits directly under the centre of the groove. This realigns the pull of the quadriceps so the kneecap tracks straight. The repositioned bone is held in place with small pins.

Soft Tissue Balancing The joint capsule and supporting soft tissues around the knee are adjusted. On the side where the kneecap was slipping, the tissue is tightened (imbrication). On the opposite side, it is released. This helps maintain the kneecap in the correct position after bony correction.

In some Grade III–IV cases, or when bone deformity is significant, additional procedures like corrective osteotomy (cutting and realigning the femur or tibia) are needed. These are more complex surgeries done by specialist surgeons.

Recovery After Surgery: What to Expect Week by Week

Recovery from luxating patella surgery is not optional it is what protects the repair while tissues heal. According to SpectrumCare, strict activity restriction lasts 6–8 weeks, with a gradual return to normal activity afterward.

Home environment changes that genuinely help recovery:

• Non-slip mats on all tile, marble, and wooden floors India's homes are particularly high-risk for slipping
• Ramps or steps to the sofa or bed if the dog normally sleeps there (better than lifting and dropping)
• Remove access to stairs during strict recovery
• Keep the E-collar on unless directly supervised small dogs can reach the incision faster than you expect

Long-Term Management: Life After Diagnosis

Patellar luxation is a structural condition. Even after successful surgery, the knee is not identical to one that was never affected. Long-term joint health requires ongoing attention.

Weight for life. This matters more after surgery than before. A lean body condition protects the repaired knee and slows arthritis. At every vet visit, ask for a body condition score and adjust feeding if needed.

Joint-supportive diet. A diet rich in Omega-3 fatty acids (EPA and DHA), collagen, and chondroitin supports long-term joint health. VET PRO MOBILITY DRY FOOD (on Animeal) is specifically formulated for dogs with mobility concerns, containing Green-Lipped Mussel Extract, Chondroitin Sulfate, Hydrolyzed Gelatin, and Norwegian Salmon Oil. It is suitable for all life stages, including small dogs recovering from orthopaedic surgery.

Year-round joint supplements. Glucosamine and chondroitin supplements work best when given consistently over months and years, not just during flare-ups. Most dogs with patellar luxation benefit from continued supplementation even after surgery, because the knee will develop some degree of arthritis over time.

Traction at home. Marble, polished tile, and wooden floors are genuinely risky for dogs with unstable knees before and after surgery. Non-slip mats are one of the cheapest and most effective home modifications you can make. Yoga mats cut to size work well in specific problem spots.

Physiotherapy / rehabilitation. For higher-grade cases or dogs recovering from surgery, a rehabilitation plan exercises to rebuild thigh muscle strength significantly improves long-term outcomes. If a rehabilitation vet or physiotherapist is available in your city, this is worth exploring.

Watch for cruciate disease. Dogs with patellar luxation have a higher risk of developing cruciate ligament injury in the same or opposite knee. Know the signs: sudden severe lameness, swelling, and a dog that simply will not put weight on a back leg. This needs a vet assessment urgently.

Indian Pet Parent Corner: Small Breeds and the Marble Floor Problem

India has a very large population of small breeds Shih Tzus, Lhasa Apsos, Pugs, Pomeranians, and Indian Spitz in urban homes. These are exactly the breeds most predisposed to patellar luxation. And Indian homes almost universally have polished marble, granite, or tile floors perhaps the worst possible surface for a dog with an unstable kneecap.

The combination is not a coincidence. Slipping and scrambling on hard floors does not cause patellar luxation, but it absolutely worsens symptoms and accelerates cartilage damage in dogs who already have loose kneecaps. Non-slip mats throughout the home are not a luxury for these dogs they are a medical necessity.

The second gap: the skip is almost always attributed to something else. "She stepped on something." "She must have twisted it." "She pulled a muscle jumping off the sofa." Indian pet parents through no fault of their own often don't associate the intermittent hop with an orthopaedic condition. By the time a vet confirms Grade III, cartilage damage is often already significant and surgery is more complex than it would have been at Grade II.

If your small or toy breed is doing the skip-hop even occasionally, get it evaluated. A Grade I or Grade II diagnosis caught early gives you options and time.

FAQ

Is the skip-hop always patellar luxation?
The skip-hop pattern is very characteristic of patellar luxation, but other conditions can cause intermittent hind-leg lameness, including cruciate ligament injury, hip problems, and muscle cramps. The key difference is that patellar luxation usually self-resolves within a few steps (because the kneecap snaps back in), while cruciate injuries tend to produce sustained non-weight-bearing. Only a vet examination with physical palpation of the knee can confirm which condition is present.

Does my dog need surgery for a Grade II luxating patella?
Not necessarily, but it depends on how symptomatic your dog is. A Grade II dog with infrequent skipping and no arthritis can reasonably be monitored with weight control and joint supplements. A Grade II dog with frequent lameness, obvious discomfort, or rapid-onset arthritis on X-rays is a better surgical candidate. This decision should be made with your vet based on your dog's individual presentation, not on grade alone.

Can patellar luxation come back after surgery?
Yes. The most common post-operative complication is recurrence of the luxation. This happens in roughly 10–20% of cases. Risk is higher in dogs with more severe deformity, very shallow grooves, or where bone alignment correction was incomplete. A second surgery is possible and can still be successful, but this is why choosing a vet or specialist with good orthopaedic experience matters.

My Shih Tzu is 7 years old and was just diagnosed with Grade III. Is she too old for surgery?
Age alone is not a reason to avoid surgery. Senior dogs undergo anaesthesia safely with proper pre-surgical screening (bloodwork, heart assessment). Many older dogs with Grade III–IV patellar luxation have significantly improved quality of life after surgical correction. The decision involves age, general health, degree of existing arthritis, and expected recovery your vet will help you weigh this honestly.

Both my dog's knees are affected. Do they need surgery at the same time?
Usually no. Most surgeons recommend treating one knee at a time, with a 6–8 week recovery gap between sides. This allows the dog to bear weight on the untreated leg during recovery. In some cases, particularly for Grade I–II in the second knee, surgery may not be recommended for the second side at all if the first correction provides enough stability.

Will my dog's patellar luxation get worse over time without surgery?
In many cases, yes. The mechanical wear from repeated luxation gradually deepens cartilage damage and erodes the trochlear groove further. A Grade II can progress to Grade III over months to years. The condition also predisposes the knee to cruciate ligament injury. This is not inevitable for every dog, but it is why regular monitoring and honest reassessment matter even for conservatively managed cases.

References

1. SpectrumCare — Luxating Patella in Dogs: Grading, Surgery & Management. https://spectrumcare.pet/dogs/conditions/luxating-patella
2. VCA Animal Hospitals — Luxating Patella in Dogs. https://vcahospitals.com/know-your-pet/luxating-patella-in-dogs
3. Merck Veterinary Manual — Patellar Luxation in Dogs and Cats. https://www.merckvetmanual.com/musculoskeletal-system/arthropathies-and-related-disorders-in-small-animals/patellar-luxation-in-dogs-and-cats
4. Cornell University College of Veterinary Medicine — Patellar Luxation. https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/canine-health-information/patellar-luxation
5. American College of Veterinary Surgeons — Patellar Luxation. https://www.acvs.org/small-animal/patellar-luxation