Knuckling in dogs is usually fairly easy to recognize but can signal a variety of conditions. Integrative veterinarian, Dr. Buzby, discusses the five most common reasons for a dog to start knuckling on a front or back leg and shares some advice about caring for affected dogs.
Lameness or trouble walking is one of the top ten most common reasons why dogs are taken to see their veterinarians. When I see these patients in practice, most of them are limping or seem painful. Some dogs make it obvious which leg is affected. They might put a little bit of weight on their leg or none at all.
But plenty of my patients tend to “play it off” as nothing by the time their owner gets to the hospital. It’s almost as if they are trying to say, “No, mom, I’m fine! Really!” However, it’s a lot harder for my patients to hide their problem when they are knuckling over on one or more legs. Let me tell you a story about one of my patients to help make my point.
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Marie was a seven-year-old German Shepherd dog who presented one day for limping on her right hind leg. She lived on a large property and absolutely loved to run the big border fence with her older brother, Charlie. Marie’s mom would always tell me stories about Marie’s excellent stride and graceful sprinting. So she was very concerned about her pup on this particular day.
On physical exam, Marie seemed normal except for mild limping on the right hind limb whenever Marie took a step forward. It seemed like she was dropping her hip as she stepped. However, her hips flexed and extended well during my orthopedic evaluation.
After gathering more information, I recommended X-rays for Marie. Thankfully, I didn’t see anything out of the ordinary. I didn’t notice any signs of hip dysplasia in dogs or bone tumors. Her knees were also healthy so a torn ACL in dogs seemed less likely. I recommended an anti-inflammatory medication for Marie and talked to her mom about restricting Marie’s exercise for a week or two to help facilitate healing.
By the time Marie came back for her progress exam, she wasn’t any better. In fact she was worse. She was still limping on the right hind limb but also seemed to be losing feeling in her leg. Her right paw was now knuckling and she was starting to show similar signs on the left hind leg. She was also wobbling when she walked. Marie’s mom mentioned that Marie seemed a little more lethargic. The big question in my mind was, “What is going on to cause the knuckling and rapid progression of signs?”
What is knuckling in dogs?
When a dog’s foot rolls under as he or she stands or walks, we refer to this a knuckling. Because the dog may end up dragging the foot, paw knuckling can cause physical injury to the top or sides of the foot. Overall, knuckling is far less common in dogs than limping, but it is still important to recognize.
Why might a dog knuckle?
In some cases, paw knuckling occurs due to a problem with the dog’s nervous system. Normally, receptors in the tendons, muscles, and joints of the leg send signals through the nerves in the leg to the spinal cord and brain. This input is used to determine the position of the dog’s foot—is it upside down, right side up, placed under the dog, sticking out to the side, being held up, etc. The term conscious proprioception describes the nervous system’s coordination of signals to indicate the position of a dog’s limb.
If something interrupts the signaling pathway, the dog will not know where the limb is in space or how it is positioned. This causes proprioceptive deficits, such as:
- Placing the foot abnormally when standing
- Dragging a foot
- An uncoordinated gait (a dog that is wobbly and off balance)
Alternatively, other dogs may have a normal neurologic system but knuckle because their ligaments, tendons, or muscles are weak and cannot support their weight. This tends to occur more often in puppies or dogs with nutritional issues. However, frail senior dogs may also knuckle occasionally due to weakness.
What causes knuckling in dogs?
Now that we have discussed some general reasons a dog may knuckle, let’s move on to some of the specific conditions your vet may consider if your dog is knuckling. This is not an exhaustive list but is meant to cover the more common problems.
1. Spinal stroke (Fibrocartilaginous embolism or FCE)
Many individual bones known as vertebrae surround and protect the spinal cord. Cartilaginous discs sit between the vertebrae to act as shock absorbers and to give the dog’s back and neck the ability to flex, extend, and move side to side. These discs are great when they are healthy but can create quite a problem if they rupture.
Sometimes a small piece of a ruptured disc enters the blood stream and obstructs one of the small vessels that supplies blood to a certain part of the spinal cord. This is known as a fibrocartilaginous embolism (FCE) or spinal stroke in dogs. FCEs are more common in young giant and large breed dogs. However, they may also occur in some small breed dogs, especially Shelties and Schnauzers.
Affected dogs may suddenly cry out when running, jumping, or playing then immediately become weak or paralyzed. They may knuckle on one or more limbs, have an uncoordinated gait, and sometimes be unable to walk at all. After the initial moment of pain, dogs with a FCE are generally non-painful. This is one of the things that may make a vet suspicious of a FCE (rather than a different cause of spinal cord trauma) during the physical exam.
Your veterinarian may recommend X-rays, which are usually normal in cases of FCE. Definitive diagnosis requires an MRI. This usually means referral to a veterinary neurology specialist. Unfortunately, there is no definitive treatment except for supportive care and time. Some dogs may recover over several days to weeks but in other cases they remain permanently paralyzed.
2. Intervertebral disc disease (IVDD)
Remember how we talked about the discs that sit between the vertebrae? In addition to causing a FCE they can also cause intervertebral disc disease( IVDD) in dogs, which is divided into two types. In type I IVDD, the disc acutely ruptures into the spinal canal, and in type II IVDD, the disc degenerates over time and begins to bulge. Both of these situations put pressure on the spinal cord, which sits just above the disc. While IVDD can occur anywhere in the spine, it happens most often in the cervical (i.e. neck) or thoracolumbar area (i.e. mid-back near the junction of the last rib and the first few lumbar vertebrae).
Affected dogs may become weak or paralyzed in their rear limbs (if the problem is in the thoracolumbar region) or all four limbs (if the problem is in the neck). They are often painful in their back or neck and may knuckle or drag their feet. Severely affected dogs may be paralyzed and in some cases are unable to urinate on their own.
If your dog develops signs of IVDD, your veterinarian may recommend an X-ray to look for signs of a ruptured or mineralized disc. Sometimes, a veterinary neurologist may inject dye around the spinal cord then take an X-ray (i.e. perform a myelogram) or use an MRI or CT to find the area(s) of compression.
Some dogs with IVDD can recover without surgery after strict rest, medications and supportive care (more on that later). However, others will need IVDD surgery for dogs to remove the ruptured portion of the disc and take pressure off the spinal cord. For a paralyzed dog, emergency back or neck surgery gives the best chances of walking again. Without surgery, paralysis may be permanent. Sometimes even after surgery, some degree of weakness or paralysis may persist with severe spinal cord injuries.
3. Degenerative Myelopathy
Degenerative myelopathy in dogs is a chronic disease of the spinal cord that causes progressive paralysis. It starts out looking like arthritis or hip dysplasia, which makes it difficult to diagnose right away. Dogs may initially just be limping on one of their hind limbs but otherwise appear normal.
However, as the disease progresses, it affects the other hind leg and causes a dog to be weak, have a wobbly gait, and knuckle on one or both rear legs. Eventually, the dog becomes completely paralyzed and unable to control his or her bowels or bladder.
Degenerative myelopathy affects middle-aged and older dogs. It is most common in German Shepherds, Huskies, Retrievers, and Corgis. The exact cause of degenerative myelopathy is unknown. However, there is a mutated gene known as SOD-1 that puts dogs at high risk for developing degenerative myelopathy.
There is no definitive test for degenerative myelopathy. Blood testing can look for the presence of the mutated gene. The presence of the gene plus signs consistent with degenerative myelopathy make it the most likely diagnosis.
Unfortunately, clinical signs can progress over the span of a few weeks to several months in most cases. Occasionally a dog may defy the odds and make it a year or more. But overall the prognosis is poor because there is no cure. Therapy with aminocaproic acid, n-acetylcysteine, prednisone for dogs, and vitamin supplements may possibly help slow the progression of degenerative myelopathy.
Back to Marie
Unfortunately for Marie, she ended up having degenerative myelopathy. When I talked to her mom about the condition, she agreed that this sounded exactly like what Marie was experiencing. We decided to submit a blood sample for gene testing, and it came back positive for the SOD-1 mutation. Marie’s mom made sure to keep her comfortable and spoiled for the following two months of Marie’s life.
4. Wobbler Syndrome
This condition gets its name from the wobbly gait that most affected dogs exhibit. The exact cause is still under investigation, but it is possible that it may have a genetic basis since it is most common in Great Danes and Dobermans. Dogs with wobbler syndrome typically have spinal cord compression in their neck from either an abnormally narrow spinal canal plus intervertebral disc herniation or narrowed spinal canal due to changes to the surrounding bone. In addition to compressing the spinal cord, these changes may also put pressure on the nerves as they exit the spinal cord.
Dogs with wobblers tend to have an unsteady gait which is more pronounced in the rear legs. They may also knuckle their paws, have difficulty getting up, or appear weak. Nerve compression can cause significant pain and affected dogs may walk with their heads lowered. Signs tend to show up in Great Danes around the age of three years and Dobermans around six years.
If your vet suspects your dog may have wobbler syndrome he or she will most likely start by taking X-rays to look for any bone changes or signs of other conditions. Then he or she may refer you to a veterinary neurologist for advanced imaging such as a myelogram, CT, or MRI.
Some dogs with wobblers will do well with medications, supportive care, and lifestyle changes such as avoiding leashes that go around the neck. Other dogs may benefit from surgery. A study in the Journal of the American Veterinary Medical Association demonstrated that the average survival time for dogs with wobblers is approximately four years regardless if they had medical or surgical management.
5. Carpal flexural deformity
This condition is a bit different than everything else on the list because it doesn’t come from a problem with the nervous system. The exact cause is unknown. However, researchers believe it may result from some combination of genetic predisposition plus nutritional factors in rapidly growing puppies. It is thought that a diet with excess protein and few other core elements like carbohydrates can cause painful growth spurts that result in this condition.
Carpal flexural deformity mostly affects large and giant breed puppies, usually younger than four months of age. As the name indicates, it affects the puppy’s carpus (i.e. wrist—the joint on the front leg between the elbow and the foot). The puppy may have hyperextension, hyperflexion or general laxity (i.e. looseness) of the carpus. Additionally, the carpus could be bowed inward (i.e. varus deformity) or outward (i.e. valgus deformity). This combination of changes may make the carpus appear to be knuckled over.
The good news is that most affected dogs improve within one to three weeks of diagnosis. Sometimes a diet change (i.e. to a balanced or energy restricted diet) and/or soft splints to support the legs may be beneficial during the recovery period.
How can I help my dog who is knuckling?
As you can see, there are many reasons a dog may be knuckling. Some may resolve with supportive care and time while others may require surgery. And still others may never go away. There are many ways you can support your dog after he or she is diagnosed with a condition that causes knuckling.
1. Give the gift of traction
My signature product, Dr. Buzby’s ToeGrips® dog nail grips, can work wonders for dogs who have an unsteady gait and are knuckling, prone to slipping, or weak. They can help your dog regain traction and walk with confidence on slippery floors that otherwise might pose a mobility problem.
Plus, ToeGrips somehow seem to provide feedback to the brain and spinal cord to help enhance a dog’s conscious proprioception. If you remember from the beginning, conscious proprioception is the nervous system’s way of telling where a dog’s limbs are in space. Dogs who are knuckling usually do so because they have altered conscious proprioception. ToeGrips may help them by reminding the dog’s brain to pick up the paws, thus improving the dog’s gait.
ToeGrips not only help these dogs with stability and confidence, they can also serve to take the brunt of chronic trauma to the nails from dragging. Over time, if the dog’s conscious proprioception does not improve, the nails can start to wear in a funny pattern or even wear back to bloody “stumps.” ToeGrips, when glued in place, can protect the nail from this demise.
For dogs who are scuffing or dragging their feet, we recommend an alternative application method—affixing ToeGrips to the nails with super glue. This is not necessary for most dogs, but for dogs who drag/scuff their paws, that altered gait tends to tug the ToeGrips off the nails. Super Glue is the simple solution to keep the ToeGrips securely in position. I demonstrate application of ToeGrips using glue in this video:
2. Reduce inflammation and pain
Some conditions such as IVDD and wobbler syndrome may cause considerable pain and inflammation. Thus, your vet may prescribe medications such as non-steroidal anti-inflammatories (NSAIDs), tramadol for dogs, gabapentin for dogs, steroids like prednisone, or other medications.
Always give all medications as directed and notify your vet immediately if you notice any concerning side effects. Never decide to give your dog your own pain medications as human pain-relievers like Advil can be toxic for dogs.
Some dogs may also benefit from laser therapy for dogs, which has several benefits including:
- Pain relief
- Improved healing
- Decreased swelling and inflammation
3. Help your dog get up and walk
Some dogs who are knuckling may also be weak or paralyzed, making it difficult for them to stand up or move from place to place. Two of my favorite mobility aids are the GingerLead® Support and Rehabilitation Harness, and the Help ‘Em Up® Mobility Harness. Both products can help save your back and are much more comfortable for you and your dog than using a towel as a sling (although that does work in a pinch).
Permanently paralyzed or significantly weak dogs may also do well with a wheelchair in some situations. Your vet can recommend some good companies to purchase a wheelchair from. Alternatively, there are plans online for making a doggy wheelchair. Always ensure the wheelchair fits your dog well (which is where purchasing it through a reputable company with good customer support can help) and check your dog frequently for any rub sores.
4. Find a rehab vet
In many situations, dogs can benefit from physical therapy just like people do. You may be able to find a veterinary professional who specializes in rehabilitation and physical therapy in your area. Alternatively, some general practice vets also provide rehab services.
The rehab vet can evaluate your dog and help design an exercise program specifically for him or her. They will most likely do some exercises with your dog and teach you how to do the exercises at home too. Some rehab vets may also have an underwater treadmill or a hydrotherapy pool. Both of these can be very beneficial as the buoyancy of the water will help support your dog. Plus, many dogs quite enjoy their time in the water!
5. Protect your dog’s feet
If your dog is dragging his or her feet or knuckling, sometimes the tops or side of the feet may get scraped up. This is especially a problem when walking on more abrasive surfaces like concrete. To protect your dog’s feet, try to stick to soft surfaces like grass while outside. If your dog requires hind end support for walking, try to hold him or her in a position where the legs aren’t dragging but the dog can still attempt to walk to build strength (if appropriate).
You can also consider using PawZ Boots for short periods of time. They are thin (think latex balloon) so they don’t pose as big of a tripping hazard as bigger bulky booties but still offer some protection. I always caution owners to read the instructions carefully when using PawZ, because they do have the potential to effect obstruct circulation to the paw and are not intended to be left on continuously.
If you notice knuckling, contact your vet
The most important thing you can do for your dog is to stay in close contact with your vet and any specialists you are working with. Since there are a variety of causes of knuckling with different outlooks and treatments, the first step is to get a diagnosis as soon as possible.
Once you know what you are dealing with, ask all your questions and do your research (using reputable sources) to find out as much as possible about your dog’s condition and how you can help. And of course, keep loving on your dog and treasure the time you have together. Have confidence that you can tackle whatever is in front of you.
Have you noticed your dog knuckling? What was the cause and how did you help your pup?
Please comment below.