What Your Dog’s Limp Is Trying to Tell You

What Your Dog’s Limp Is Trying to Tell You

STORY AT-A-GLANCE

  • Patellar luxation (aka “floating kneecap”) is a common genetic defect in primarily small breed dogs in which the kneecap pops out of place. There are four levels of severity — Grade 1 is the mildest and Grade 4 is the most severe; the speed at which the condition progresses depends on a variety of factors
  • The distinguishing symptom of patellar luxation is the sudden lifting of one hind limb in what is often described as a “skip”; additional signs include a limp that comes and goes, bowlegged hind limbs, a hunched lower back, and cracking or popping noises when the knee is bent
  • Ideally, patellar luxation should be proactively managed as soon as it’s diagnosed; mild severity luxations can be effectively controlled by maintaining a healthy weight, exercise, joint support supplements, chiropractic care, acupuncture, and an anti-inflammatory diet
  • Surgery for a luxating patella should only be undertaken after all nonsurgical interventions have been tried, or in the case of dogs who can’t walk or run without pain, are lame and/or have diminished quality of life

A luxating patella is unfortunately rather common in dogs. It’s a condition in which the kneecap (patella) in one or both back legs shifts sideways (luxates), away from its normal position at the front of the knee. It’s sometimes referred to as a dislocated or “floating” kneecap.

Most of the time, the kneecap shifts inward, in the direction of the other leg, in what is called a medial patellar luxation (MPL). This version is seen more often in smaller dogs. If the shift is instead outward, it’s called a lateral patellar luxation (LPL), and is more common in larger dogs.

Mechanics of a Luxating Patella

Your dog’s kneecap sits in the same place in her leg as your does, which is at the distal or far end of the femur, or thighbone. It sits much like a pea in a pod and helps the quadriceps muscles move smoothly across the joint between the thigh and lower leg.

The kneecap moves up and down in a wedge-shaped groove right on the thighbone. The patella ridges hold the kneecap in place, and as long as the ridges are deep, the kneecap can only move up and down as nature intended.

Unfortunately, some dog breeds have a very flat patella ridge. This means the kneecap doesn't seat snugly in the groove and it can pop out either medially, to the inside, or laterally, to the outside.

Symptoms to Watch For

The distinguishing sign of a luxating patella is the sudden lifting of one hind limb. Your dog is walking along fine and then she raises a back leg and perhaps hops for a step or two. The affected leg may be held close to the body or extended backwards. This is often termed a “skip” by both owners and veterinarians. Then she puts the leg back down and continues on as if nothing happened.

Or out of the blue one day your dog lifts a back leg and yelps or cries while holding the leg off the ground. You can’t imagine what happened because a few seconds ago he was walking normally or running around playing. Then just as suddenly, he lowers his leg and starts walking or running around again normally.

It’s like sudden, acute lameness that disappears just as quickly. It can be quite concerning and confusing for pet parents and is definitely a sign of a luxating patella. What has happened is your dog’s kneecap popped out of place, stopped him in his tracks and caused him to hold his leg up to try to relieve the discomfort.

Then the kneecap returned to its original position, he was able to put his foot back on the ground, and off he went. Pet parents tell me, “My dog went suddenly lame, holding up a back foot, and then just as suddenly he was not lame.” That's a pretty typical description of what happens with the condition known as luxating patella.

Additional signs of a luxating patella are also seen in other orthopedic conditions, including a limp that comes and goes, bowlegged hind limbs, a hunched lower back, and cracking or popping noises when the knee is bent.

Dogs at Highest Risk for Patellar Luxation

The genetic predisposition to floating kneecaps occurs in several small breed dogs, including:

  • Miniature and Toy Poodles
  • Yorkies
  • Chihuahuas
  • Maltese
  • Pomeranians
  • Papillons
  • Jack Russell Terriers
  • Pekingese
  • Boston Terriers

Short-legged dogs, for example Basset Hounds and Dachshunds, aren’t genetically prone to the condition. However, because their femurs are so short, it can change the angle of the seating of the kneecap, and these dogs can end up with luxating patellas as well.

Larger breeds have less genetic predisposition to problems with the kneecap. They typically have a nice, deep groove for the patella to seat in. However, some larger dogs are prone to hip problems. If a joint above the kneecap like the hip joint, or one below the kneecap like the ankle develops a problem, it can change the ergonomics of the body.

If there's a problem with your dog's hip, it can eventually force the patella out of its groove. Large and giant breed dogs with hip dysplasia often have a secondary condition of luxating patella caused by the malformation of the hip joint. If the knee problem shows up first, when we x-ray the knee, we often learn the dog has hip dysplasia.

Diagnosis and Grading the Severity of the Luxation

A physical examination is typically the only thing needed to diagnose a luxating patella in dogs. In fact, the condition is often diagnosed incidentally during a routine wellness exam, or during an exam for a different problem. Patellar luxation can also be seen via imaging tests such as x-rays, CT scans, or MRIs, but these diagnostics aren’t commonly used to make the diagnosis.

There are four levels of severity of a luxating patella. Grade 1 is the mildest; Grade 4 is the most severe.

  • A Grade 1 luxating patella describes a kneecap that pops out (or can be manually popped out of place by a veterinarian), but pops right back in on its own.
  • Grade 2 describes a kneecap that pops out of place and doesn't always pop back in automatically, sometimes requiring manual manipulation to re-seat it.
  • A Grade 3 condition is when the kneecap sits outside its groove most of the time, but can be manually positioned back in the groove, where it stays temporarily.
  • Grade 4 luxating patella is the worst-case scenario. The kneecap sits outside the groove all the time and won't stay seated in the groove when it is manually popped into place.

It’s important to understand that a displaced kneecap can cause intense pain for your pet. Often in young dogs with strong, resilient joint cartilage, the patella can pop out and back in without obvious signs of pain. There may be an intense jolt of pain as the kneecap moves across the patella ridge, but it's gone in a flash and is usually not obvious to an observer.

The dog won't want to put weight on his leg until the kneecap has popped back in (which can cause another flash of pain), but otherwise he appears fine. Here’s why: The femur and the kneecap are covered with cartilage. Cartilage doesn’t have a nerve supply, so the pain of the bone sitting in the incorrect position isn’t fully noted until the cartilage is completely gone.

However, as the cartilage wears down from the frequent travel of the kneecap in and out of its groove, there will be nerve-to-nerve and ultimately, bone-to-bone contact and the condition can become extremely painful for your pet. The speed at which degeneration occurs depends on the size of your pet, the severity of the luxation, and the amount of use and abuse those rear limbs take. In well-muscled dogs, changes tend to occur more slowly because muscle tone holds the skeletal system in place, including the kneecaps.

Never underestimate the benefit of excellent muscle tone in helping to slow down the progression of this condition.

5 Steps to Proactively Manage Mild Luxations

If your dog is diagnosed with even a mild Grade 1 luxating patella, I recommend you address it right away. The quicker you take a proactive approach to treating the condition, especially in a young dog, the better your chances of avoiding surgery down the road, as well as degenerative joint disease or arthritis and a decreased quality of life.

  1. The first thing you should do is help your dog achieve and maintain an ideal body weight. The heavier the dog, the more burden there will be on his knees. Optimal body weight for your dog means lots of lean muscle and a reduced amount of fat. Keeping him lean will limit stress on the joints.
  2. Number two, it's very important to keep your dog moving. Maintaining excellent muscle tone will help your dog's body form kind of a cage around the knee that will help keep stabilize the patella. No matter how many supplements you give your dog, they can’t create good muscle tone or body condition. Daily aerobic, heart-thumping exercise to intentionally build muscle tone is essential.

    If you can’t physically do this for your dog, or if your pet is too painful or obese to move at high intensity, I strongly encourage you to send her to a physical therapist or a rehab therapist who can get her on an underwater treadmill.

  3. The third thing I recommend is to provide your dog with oral joint support in the form of glycosaminoglycans, or GAGs. These are the raw building blocks for cartilage repair and maintenance. There are several different types of GAGs on the market specifically for veterinary use. However, I typically use human oral joint support supplements to help maintain the integrity of the knee cartilage while also improving joint fluid production.

    These include SAMe, glucosamine, chondroitin, Perna mussel, collagen, cetyl myristoleate, methylsulfonylmethane (MSM) and several natural anti-inflammatories, including curcumin, which can help with pain.

    I recommend you discuss the situation with your integrative veterinarian, who will be able to suggest and, in many cases, provide the right supplements to rebuild and maintain strong and resilient cartilage and joint fluid production in your dog.

    I suggest you also discuss Adequan with your vet. Adequan is an injectable GAG that helps dogs who are developing premature arthritis. It slows down joint degeneration and improves joint fluid production.

  4. Chiropractic and acupuncture can also be very beneficial for reducing pain and limiting wear and tear on the rest of the body. If you have a puppy with a luxating patella, there are some very effective chiropractic manipulations that can keep the hips and knees in good alignment and help slow the progression of the disease. I recommend you start chiropractic care as soon as the diagnosis is made.
  5. I also recommend feeding your dog a nutritionally balanced, species-appropriate diet that is naturally anti-inflammatory. By feeding an anti-inflammatory diet (one very low in carbohydrate content), you can help reduce or moderate the effects of inflammation in his body, including the joints.

    Because carbs aren’t listed on pet food labels, you’ll need to calculate them using the following formula, plugging in the values found on the guaranteed analysis on the package label:

    100 – % protein – % fat – % moisture – % ash (if not listed, assume 6%) = % carbs

    Fiber is the indigestible roughage that doesn't break down into sugar, so you don't have to include it in the formula.

    So, break out your calculator and actually do the math, because I want you to be sure you’re feeding your dog with a luxating patella less than 10% carbs. A low-carb diet will help minimize the pain associated with the condition.

Surgical Intervention for Patellar Luxation

Many veterinarians often recommend surgery for a luxating patella, regardless of the severity of the condition. Sadly, I regularly hear from dog parents who’ve been told to do none of the above suggestions. They’ve been told to simply wait until their dog is in crippling pain or the knee has degenerated to the point where the animal is totally lame, and then make an appointment for surgical repair.

I'm not a proponent of waiting and doing nothing, nor am I a fan of doing surgery unless the condition is absolutely destroying a dog's quality of life. If your pup can't run or walk without intense pain or is having lameness associated with decreased quality of life, then you should absolutely consider surgical correction, but not before you’ve exhausted all nonsurgical options to improve your pet’s quality of life.

Sources and References

  • PetMD, October 21, 2021
  • Cornell Richard P. Riney Canine Health Center