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Medial Patellar Luxation in Small vs. Large Dogs

Medial Patellar Luxation in Small vs. Large Dogs

Medial Patellar Luxation

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Learn how medial patellar luxation affects small vs. large dogs—compare symptoms, treatment options, surgery needs, recovery, and care tips by size

By 

Sustainable Vet Group

Updated on

July 28, 2025

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Medial Patellar Luxation in Small vs. Large Dogs

What Is Medial Patellar Luxation (MPL)?

Medial Patellar Luxation (MPL) is a knee condition where the kneecap (patella) slips out of its normal groove toward the inside of the leg. This makes the joint unstable and can lead to limping, pain, or changes in how your dog walks.

MPL is different from Lateral Patellar Luxation (LPL). In MPL, the kneecap moves inward (toward the other leg). In LPL, it slips outward. MPL is much more common, especially in small dogs.

When the patella doesn’t stay in place, the knee joint becomes weak and unstable. Over time, this can cause joint damage, pain, and arthritis if not treated.

MPL is graded by severity:

  • Grade I: Kneecap pops out but goes back easily
  • Grade II: Slips out more often, may cause limping
  • Grade III: Stays out, but can be moved back by hand
  • Grade IV: Always out and can’t be returned without surgery

Understanding the grade helps guide the right treatment for your dog’s needs.

How MPL Differs Between Small and Large Dogs (Quick Comparison)

MPL appears in both small and large dogs, but it behaves differently depending on the dog’s size. Small dogs usually have it from a young age, often due to genetics. In large dogs, MPL may develop later and is sometimes linked to trauma or uneven growth. Understanding these differences helps in planning the right treatment and recovery.

Key differences include:

  • Prevalence: MPL is more common in small dogs, while large dogs may have lateral luxation more often.
  • Type of Luxation: Small dogs typically have medial luxation; large dogs may develop medial or lateral types.
  • Common Breeds: Small breeds include Pomeranians, Chihuahuas, and Poodles. Large breeds include Labradors and German Shepherds.
  • Severity and Grading: Small dogs usually have mild to moderate (Grade I–II) MPL. Large dogs often show severe grades (III–IV).
  • Age of Onset: Small dogs often show signs before 1 year old. In large dogs, signs may appear later.
  • Bone Deformity Likelihood: Small dogs have a higher chance of congenital bone deformities. Large dogs may develop changes over time.
  • Surgical Approach: Surgery in large dogs is more complex due to size and joint stress. Small dogs often respond well to simpler procedures.
  • Recovery Outlook: Small dogs recover faster and need less rehab. Large dogs may require longer recovery and stricter care.

Read more | Signs and Symptoms of Medial Patellar Luxation in Dogs

Which Breeds Are Most at Risk?

Certain dog breeds are more likely to develop Medial Patellar Luxation (MPL) due to inherited traits and body structure. Genetics play a major role, especially in small dogs, where MPL often shows up early in life. Large breeds can also be affected, though less frequently, and often with more complex presentations.

Small breeds most at risk include:

  • Yorkshire Terrier
  • Pomeranian
  • Chihuahua
  • Miniature and Toy Poodle
  • Pekingese

These breeds are often born with shallow knee grooves or loose ligaments, making it easier for the kneecap to slip out of place.

Large breeds that may develop MPL include:

  • Labrador Retriever
  • Flat-Coated Retriever
  • Great Pyrenees
  • Akita
  • Newfoundland

In large breeds, MPL may not appear until later in life and can be linked to trauma, poor joint alignment, or fast growth during puppyhood.

While not every dog in these breeds will get MPL, their genetic makeup increases the risk. Breeders are encouraged to screen for joint issues and avoid breeding dogs with known luxation problems.

If your dog belongs to one of these breeds, keep an eye out for early symptoms like limping or skipping steps, and have your vet assess their knees during routine checkups. Early detection gives your dog the best chance at long-term joint health.

Read more | Recovery After Medial Patellar Luxation Surgery in Dogs

Symptoms in Small vs. Large Dogs

The signs of Medial Patellar Luxation (MPL) can look different depending on your dog’s size. Small dogs often show quick, obvious signs, while large dogs may hide discomfort until it worsens.

In small dogs, the kneecap may pop out and back in during movement. This causes:

  • Limping that comes and goes
  • A sudden “skipping” step during walks
  • Temporary leg lifting followed by normal walking
  • Mild pain or licking at the knee

These signs may be brief but happen often, especially after play or getting up from rest.

In large dogs, symptoms can be harder to spot at first. Instead of skipping steps, they may show:

  • Slow or stiff movements
  • Reluctance to exercise or climb stairs
  • Subtle lameness that worsens with activity
  • Trouble rising or turning quickly

Some dogs have bilateral MPL, meaning both knees are affected. This can make them walk stiffly or show signs in both legs.

If your dog shows any of these changes, even if mild, it’s important to see your vet. Early diagnosis helps prevent long-term joint damage and allows for better treatment planning tailored to your dog’s size and condition.

Read more | How to Tell If Your Dog Has a Medially Luxating Patella

Diagnosis and Grading in Both Size Groups

Medial Patellar Luxation is diagnosed through a physical exam and imaging. Your vet will check how easily the kneecap moves out of place and assess joint function. This helps decide the severity and treatment.

The grading system is the same for all dogs:

  • Grade I: Kneecap moves out easily but pops back in
  • Grade II: Slips out on its own and stays briefly
  • Grade III: Always out but can be moved back by hand
  • Grade IV: Always out and can’t be moved back

X-rays are used to confirm joint structure and rule out other issues like hip dysplasia or trauma. This is especially important in large breeds, where symptoms may overlap with other orthopedic conditions.

Common misdiagnoses in large dogs include arthritis, hip problems, or muscle strain. That’s why a full orthopedic exam is key, not just looking at gait.

Although the grading is the same, large dogs may have more bone involvement or need more detailed imaging. Small dogs often show clearer signs during a basic exam. In all cases, grading helps guide whether surgery or conservative care is the right path.

Treatment Options: Small Dogs vs. Large Dogs

The choice between surgical and non-surgical treatment depends not just on the grade of MPL but also on your dog’s size. Small and large dogs respond differently to conservative care.

Small dogs with Grade I or II often improve with:

  • Weight management
  • Joint supplements
  • Controlled exercise
  • Bracing and physiotherapy

These treatments can stabilize the knee and reduce symptoms without surgery. Small dogs benefit from lighter body weight and lower joint stress.

Large dogs, even with Grade II, may require surgery because:

  • Their size adds pressure to the joint
  • Conservative care may not fully control the luxation
  • Mobility problems worsen faster with weight-bearing stress

Challenges by size include:

  • Harder to limit large dogs’ movement indoors
  • Weight loss is slower in big breeds
  • Braces are harder to fit and keep in place

For both groups, combining care—like supplements, therapy, and lifestyle changes—can reduce pain and protect the knee. But large dogs are less likely to succeed with non-surgical treatment alone. Your vet will consider all factors before creating a plan.

Read more | Medial Patellar Luxation Treatment Without Surgery

Surgery: What’s Different by Dog Size?

Surgical treatment for MPL is common and effective, but the approach depends heavily on your dog’s size and the grade of luxation.

Small dogs usually need simpler procedures such as:

  • Trochlear sulcoplasty (deepening the groove for the kneecap)
  • Soft tissue release or tightening
  • Tibial tuberosity transposition (in more advanced cases)

These surgeries are effective in most small breeds and carry a low risk of complications when done early.

Large dogs often require more advanced techniques like:

  • Corrective osteotomies (cutting and realigning the bone)
  • Use of surgical implants for joint support
  • More extensive soft tissue reconstruction

Key differences in large breeds:

  • Higher force on the joint requires stronger repairs
  • Increased anesthesia risk due to body weight
  • Longer surgical time and more complex aftercare

Post-op care also varies. Small dogs may return to light activity in 4–6 weeks. Large dogs may need 8–12 weeks of structured rehab and close monitoring.

Surgical success is high in both groups, but choosing the right procedure for your dog’s size is critical for long-term joint health and mobility.

Read more | Best Exercises and Rehab for Dogs After MPL Surgery

Recovery and Prognosis: What to Expect

Recovery from MPL surgery or conservative care varies by dog size, but most dogs show excellent outcomes with proper treatment.

Small dogs often bounce back faster due to their lighter weight and easier mobility control. With routine care and basic rehab, many are back to normal within 4–6 weeks. Risks like implant failure or complications are rare if surgery is done early.

Large dogs may need:

  • More time to heal
  • Ongoing physical therapy
  • Strict activity limits for 8–12 weeks
  • Closer monitoring for complications like joint swelling or stiffness

Success rates for both groups are high—over 90% in most cases. However, complications are more common in large dogs due to size, strength, and stress on healing tissues.

Long-term, most dogs regain normal function and show no signs of lameness. Some may need continued supplements or periodic vet checkups to keep joints healthy.

Whether surgical or non-surgical, the key to a good recovery is sticking to the plan, avoiding overuse, and adjusting care based on your dog’s response. Vet-guided follow-ups improve long-term outcomes significantly.

Cost Differences in Treatment

Cost is another important factor when deciding how to treat MPL, and it varies greatly between small and large dogs.

Surgical costs for small dogs are typically lower due to:

  • Smaller bone and joint size
  • Simpler procedures
  • Less anesthesia and material use

Most small dog MPL surgeries cost $1,500–$2,500 depending on location and hospital fees.

Large dog surgeries are more expensive due to:

  • Longer surgical time
  • Larger implants or plates
  • Increased anesthesia needs
  • More rehab or post-op care

For large breeds, costs may range from $3,000–$5,000+, especially if bone realignment or custom plates are needed.

Non-surgical costs include:

  • Joint supplements ($30–$80/month)
  • Rehab or hydrotherapy sessions ($50–$100/session)
  • Braces ($100–$400 depending on size)

Budgeting ahead is essential. Ask your vet for a full breakdown of possible costs for both surgical and non-surgical options. Some clinics offer payment plans or referrals to orthopedic specialists with package pricing.

Choosing the right treatment should balance cost, outcome, and your dog’s long-term comfort.

Read more | How to Prevent Medial Patellar Luxation in Puppies

Managing MPL at Home: Tips by Dog Size

Managing MPL at home requires adapting your environment and care routine to suit your dog’s size. Small and large dogs need different setups for safety and support.

For small dogs:

  • Use pet stairs or carry them to avoid jumping
  • Place soft mats or rugs in walkways to prevent slipping
  • Choose braces designed for toy or small breeds
  • Encourage short leash walks to build strength

For large dogs:

  • Use ramps for cars or beds
  • Block access to stairs with baby gates
  • Add non-slip flooring in main rooms
  • Use heavy-duty braces made for large breeds
  • Focus on structured, slow-paced exercises

For all dogs:

  • Keep weight under control with portioned meals
  • Stick to your vet’s rehab or supplement plan
  • Avoid off-leash running or rough play

Customizing care by size helps reduce joint stress and supports long-term joint health. Your vet or canine therapist can give breed-specific advice to improve comfort and prevent flare-ups.

Read more | Grade 2 Medial Patellar Luxation: Surgery Decision Guide

Final Thoughts: Does Dog Size Change the MPL Plan?

Yes—dog size has a big impact on how MPL is managed. From diagnosis to treatment and recovery, small and large dogs face different challenges and require tailored plans.

Small dogs often respond well to conservative care or simple surgery. They recover quickly, and the procedures are usually less costly. Large dogs may need more complex treatment, longer rehab, and closer monitoring due to their size and weight.

Major points to remember:

  • MPL is more common in small breeds
  • Symptoms may be subtle in large dogs
  • Treatment should match the dog’s grade and size
  • Surgery is often more urgent in large breeds
  • Recovery time and cost are higher in larger dogs

Early diagnosis, consistent care, and working closely with your vet give your dog the best chance for a pain-free, active life. Whether small or large, your dog can recover well with the right plan.

FAQs

Is MPL more serious in large dogs than small dogs?

Yes, MPL tends to be more serious in large dogs. Their size puts more pressure on the knee joint, which can lead to faster joint damage and a higher need for surgery. Larger dogs also face more complex surgeries and longer recovery times compared to smaller breeds with the same grade of luxation.

Can large dogs recover without surgery?

Some large dogs with mild MPL may improve with non-surgical care, but this is less common. Their heavier weight makes it harder to manage joint stress with therapy alone. Surgery is often recommended for long-term stability and comfort, especially for Grade II or higher cases in large-breed dogs.

Are certain breeds more prone to complications?

Yes, large breeds like Labrador Retrievers or Great Pyrenees are more prone to surgical complications due to their size and joint stress. Small dogs generally recover faster and with fewer issues. Dogs with severe grades or other orthopedic problems may also have higher risks during and after treatment.

Is lateral luxation more common in big dogs?

Yes, lateral patellar luxation (LPL), where the kneecap moves outward, is more common in large dogs. While MPL is still seen in big breeds, LPL tends to occur more frequently due to different bone angles and joint stresses found in larger body structures.

What is the recovery time for small vs. large dogs after surgery?

Small dogs typically recover in 4–6 weeks with light care. Large dogs may need 8–12 weeks or longer, along with structured rehab and activity limits. Recovery depends on surgery type, joint condition, and post-op care, but large dogs often take more time due to body weight and joint pressure.

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