SYMPTOM
Knuckling
Knuckling is when a dog stands or walks on the top of a paw rather than on its pads, with the toes folded under. Owners may notice a paw scuffing along the ground, nails scraping on hard floors, nails worn down on their upper surface, or a paw that stays folded over for a moment before the dog corrects it. It can affect one leg or several, and is often most visible when the dog turns, walks slowly or is tired. Dogs that knuckle often seem unaware of it, which is one reason it can go unnoticed at first.
Neurological
Most knuckling in dogs comes from the nervous system rather than from the leg itself. The paw folds over because the signals that tell the brain where the foot is (proprioception) are not getting through. In dogs this is most often spinal cord disease: a disc extruding into the spinal canal, degenerative myelopathy, a fibrocartilaginous embolism, compression of the cord in the neck (wobbler syndrome) or of the nerves at the base of the spine, infection of a disc space, or a spinal tumour. Injury to the nerves of a single leg, such as the brachial plexus after a road accident, can also leave a paw knuckled or dragged.
Musculoskeletal
Pain in a joint, tendon or muscle usually shows as lameness, with a shortened stride or a leg held up, rather than as true knuckling. A dog shifting weight away from a sore leg can look as though it is placing the paw oddly, but pain-related lameness and a loss of paw placement from nerve or spinal cord disease can be hard to tell apart without a neurological examination.
Orthopaedic
In rapidly growing large-breed puppies, typically around six to eight weeks of age, the wrist (carpus) can buckle forwards so the puppy appears to knuckle over at the joint. This carpal laxity is linked to uneven tension between the muscle groups either side of the joint, often in connection with diet during rapid growth, and in many puppies it settles within one to four weeks with a balanced diet and normal exercise. It looks different from spinal knuckling, in which the toes fold under, usually in an adult dog.
Metabolic or Systemic
Less commonly, illnesses that affect nerves throughout the body can weaken paw placement. These tend to involve more than one limb and develop over weeks, and they are a much less frequent cause of knuckling than spinal cord disease.
Vascular
In a fibrocartilaginous embolism, a fragment of disc material blocks a blood vessel supplying the spinal cord. Signs appear suddenly, often during running or jumping, and are frequently worse on one side. The condition is typically not painful, but some disc extrusions are also painless, so the two cannot be separated without advanced imaging such as MRI.
Toxic or Nutritional
Toxic and nutritional causes of nerve damage are rare in dogs in the UK. Where they occur, onset is usually gradual and more than one limb tends to be affected.
Why timing matters
Early observation
When knuckling first appears, the pattern of onset offers clues about what might be happening. A sudden appearance in a previously normal dog suggests a discrete event such as a disc extrusion, a fibrocartilaginous embolism or trauma. These can look alike at home in the first hours, and a disc extrusion can continue to worsen during that time. Gradual onset over days to weeks may point towards progressive processes such as inflammation, degenerative change, or metabolic influence. The initial context, whether during rest, activity, or particular movements, can also help characterise the nature of the change.
Later presentation
If knuckling persists or recurs, the evolution of the picture becomes informative. Worsening over time may suggest progression of an underlying process, while stable knuckling that does not change may reflect a static injury or adaptation. Intermittent knuckling that comes and goes can indicate fluctuating factors such as fatigue, pain levels, or inflammation. This longer view applies to knuckling that has developed gradually. It does not apply to knuckling of sudden onset, where the first hours carry the most information and the outcome can change within them.
Patterns of progression vary widely depending on the underlying cause. Some conditions remain stable once established, while others worsen steadily over months, as in degenerative myelopathy, or rapidly over hours, as can happen with a disc extrusion. In younger animals, developmental changes may alter the picture as growth continues. In older animals, degenerative processes may advance slowly, and the threshold at which knuckling becomes visible can shift with muscle condition, weight, or activity level. Individual variation means that timelines and trajectories differ, and isolated observation at a single point offers limited insight.
Conditions commonly associated
Degenerative Myelopathy
Loss of proprioception causes dogs to stand on the tops of their paws rather than the pads.
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Degenerative Myelopathy in Dogs
Degenerative myelopathy can cause knuckling as the progressive degeneration of spinal cord white matter disrupts the nerve signals that coordinate paw placement, often beginning with subtle dragging or folding of the toes in one or both hind limbs. This typically appears in older dogs and worsens gradually over months.
Intervertebral Disc Disease in Dogs
Knuckling may occur when intervertebral disc material compresses the spinal cord or nerves, interrupting the sensory feedback that tells the brain where the paw is in space. The degree of knuckling often reflects the severity and location of the compression. In an acute extrusion, knuckling can be an early sign that progresses within hours to weakness or paralysis, particularly in predisposed breeds such as Dachshunds.
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Fibrocartilaginous Embolism (FCE)
A fibrocartilaginous embolism can produce sudden knuckling when the blocked blood vessel supplies a section of spinal cord in the neck or back, resulting in an abrupt loss of proprioception that is often worse on one side. It is typically not painful, but some disc extrusions are painless too, so the absence of pain does not separate the two without imaging.
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Wobbler Syndrome (Cervical Spondylomyelopathy)
Compression of the spinal cord in the neck can cause knuckling and a wobbly, wide-based gait, often most obvious in the hind limbs, sometimes with neck pain. It is seen mainly in middle-aged Dobermanns and in young large and giant breeds such as Great Danes, Mastiffs and Rottweilers.
Lumbosacral Stenosis
Compression of the nerves at the base of the spine can cause the hind paws to knuckle, often with pain on rising, reluctance to jump, and changes in tail carriage or continence. It is seen most often in large breeds, particularly German Shepherds.
Discospondylitis
Infection of a disc space and the neighbouring vertebrae can press on the spinal cord and cause knuckling, usually with marked spinal pain. Brucella canis, a zoonotic infection that is reportable to APHA in England, Scotland and Wales, is one recognised cause, particularly in imported dogs.
Brachial Plexus Avulsion in Dogs
Tearing of the nerve roots that supply a front leg, usually after trauma such as a road accident, can leave the dog unable to place the paw normally, so it knuckles over or is dragged on its upper surface.
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When to explore further
If knuckling appeared suddenly, over minutes to hours. A disc extrusion can progress within hours from mild knuckling to an inability to walk and, in some dogs, to loss of feeling in the toes. Dogs that lose deep pain sensation have a much lower chance of walking again than dogs that keep it. Whether sensation is still present cannot be judged reliably at home.
If knuckling spreads to other limbs or worsens over hours or days, since a spreading or deepening pattern suggests an ongoing process in the spinal cord rather than a fixed injury.
If knuckling comes with signs of back or neck pain, such as a hunched posture, a lowered or stiff head, trembling, crying out when picked up, or reluctance to jump or use stairs. Breeds such as Dachshunds, Beagles, Shih Tzus, Lhasa Apsos and Pekingese are predisposed to disc extrusion.
If the dog has difficulty rising, sways or crosses its hind legs, cannot walk, or shows changes in bladder or bowel control such as dribbling urine or not passing urine. These signs can indicate more severe spinal cord involvement.
If there is a known history of trauma, recent illness, or exposure to unfamiliar substances that might offer context for the timing of onset.
If knuckling has developed slowly over weeks to months in an older dog without obvious pain. Degenerative myelopathy follows this pattern, usually beginning after eight years of age and progressing over six months to three years, but a slowly compressing disc or tumour can look similar and is separated by imaging.
Knuckling gains meaning when considered alongside the animal's history, the pattern of onset, and any accompanying changes in movement or behaviour. For knuckling that has built up slowly, the trend over weeks can help show whether the process is static, progressive or intermittent. For knuckling that appeared suddenly, the first hours matter more, and pain, spread to other limbs, loss of the ability to walk or a change in bladder control each carry particular weight. These observations, when shared with someone familiar with the individual animal's medical context, can inform decisions about further evaluation, what form it might take and how soon it is useful.
Last reviewed: 9 October 2026 · Dr Alastair Greenway MRCVS