What is Knuckling?

“Knuckling” and “knuckling over” are common terms used to describe loss of proprioception in dogs. Knuckling occurs when a dog’s leg and/or paw fail to flex properly when walking. This condition may first appear as scraping the toenails along the ground and progress to actually walking on the knuckles, rather than the pads of the foot.

Knuckling may be caused by spinal trauma as a result of vehicular accidents, intervertebral disc disease, fibrocartilaginous embolism as well as tumors, degenerative myelopathy and, on occasion, inflammatory or infectious etiologies. It can also be caused by general hind limb weakness that often comes with age.

Knuckling can result in a loss of balance, which can lead to painful falls. Frequent knuckling, or dragging of the paws, can also lead to abrasions and open sores, which may become infected or ulcerated. Lastly, it diminishes a dog’s enjoyment in walking which, in turn, reduces the quality of the dog’s life.

There is no treatment available that completely eliminates knuckling. Alternative therapies, such as weight control, anti-inflammatories, nutritional supplements, physical and/or water therapy and acupuncture are options. Veterinary instrumentation such as orthotic tarsal and hock braces are also available and said to prevent knuckling.

Introducing the Canine Mobility Anti-Knuckling Device™

The Canine Mobility Anti-Knuckling Device™ (AKD) is a therapy device for dogs suffering from knuckling from a wide variety of causes. It uses an adjustable elastic cord secured to a material paw strap at one end, and a dog harness at the other. The paw strap consists of a loop that fits around the dog’s two innermost toes (Phalanges) and another loop that fits around the dog’s lower leg bones (Metatarsus). The unique design of the AKD differs from all others in that it brings the affected leg forward while simultaneously lifting the toes, effectively reducing or eliminating knuckling. The device has proven to be effective, comfortable, and easy to use.

Kirby is a 14-year-old Labrador Retriever who fell on the ice several times in February, 2014 and was favoring his left rear leg. An MRI showed spondylosis at T13-L1, bridging and multiple disc protrusions, and osteoarthritis of some facets, specifically L3-4. Kirby knuckled occasionally but could still go on walks. He has had underwater treadmill and laser therapy and acupuncture for the 2 years. In early March, 2016, his back legs gave out after an acupuncture treatment and he was only able to walk short distances, with some knuckling and/or dragging of his hind legs. His treatments in the underwater treadmill were discontinued. Kirby began using bilateral AKDs in April 2016 and has been able to resume therapy in the underwater treadmill, shown in this video at Veterinary Orthopedics and Sports Medicine, starting with short sessions and increasing the number of minutes on each weekly visit. He alternates his use of the AKDs between the paw straps and retrofitted Ruffwear Boots.

Klaire is a 6-year-old Labrador Retriever, who in the Fall of 2012 suffered a fibrocartilaginous embolism. She had been completely paralyzed from the waist down for several weeks and after extensive rehab she regained mobility in her right hind leg but she had lost virtually all use of her left hind leg. This video shows Klaire in October 2012 walking first with a RuffWear boot on her left hind paw, and then with the AKD affixed to the boot. This was the first time Klaire had used the AKD.  The next video taken shows Klaire in July of 2013 using the AKD. The AKD has enabled her to walk again, and in doing so has strengthened her good leg and assisted in rebuilding strength in her weakened left leg. It has also significantly improved the quality of her life.

Reilly is a 13-year-old Irish Setter with arthritis and intervertebral disc disease and is 15 months post L4-S1 dorsal laminectomy. He is the first dog to use the AKD and is the dog for whom the device was invented. His knuckling began approximately two months after his surgery when we were able to resume his daily walks. He lived for these walks and it was heartbreaking to see something he enjoyed and looked forward to be the source of continued pain. The effects of knuckling are shown in this video. Reilly is also shown in this video using the AKD on his right hind leg. He had been using the AKD for one year at the time of this video. As a result of his use of the AKD, the muscles that had atrophied during the course of his recovery from surgery were strengthened and he was able to resume walking with a normal gait.

Gus is a nine-year-old Rhodesian Ridgeback who has been diagnosed with Degenerative Myelopathy (DM) and intervertebral disc disease (L7-S1). With great effort he is still able to walk on his own although he knuckles on both rear paws and has developed “wear sites” on his toes. He has been using an Eddies Wheels cart for about a month but continues to knuckle and has experienced episodes of bleeding of the nails and on the tops of his paws.  Gus is shown in this video using his Eddies Wheels cart. The cart takes some of the weight off his hind legs and allows him to continue walking with all four legs. He has, however, continued to have problems knuckling and dragging his hind legs. Although the wheel of his cart blocks the view of his knuckling, there is evidence that it is occurring every time he takes a step and his foot does not move forward to the point where it can be seen in front of the wheel. In this video, Gus has bilateral AKDs affixed to his Eddie’s Wheels cart to prevent him from knuckling. The shock cords are attached to the cart’s frame on either side of Gus’s shoulders instead of the typical arrangement in which they are connected to a harness. He had been using the AKDs for one month at the time of this video and a noticeable reduction in the frequency of his knuckling can be seen.