But after researchers took some cells from the dog's nose -- that's right, his nose -- and implanted them in his injured spine as part of a new study, Jasper could walk again.
"Now, he whizzes around the house and garden and is able to keep up with the other dogs," Hay told BBC. "It's wonderful."
Jasper was one of 34 dogs with paralyzed hind legs to participate in a randomized, double-blind study at Cambridge University in England. The results have now been published in Brain, a neurology journal. Researchers first collected olfactory "ensheathing" cells from the dogs' noses, cultured them in Petri dishes for three to five weeks and then injected them into the dogs' spines.
Researchers assessed the dogs' mobility on treadmills before and after treatment, discovering that the cells didn't restore communication between the brain and the hind legs, but somehow restored mobility and coordination to the legs.
The researchers concede they're not sure exactly why they had the success that they did.
"For those dogs that had the cells, something about having those cells in their spinal cord made them walk better, a little better, but not as if they were never injured," said spinal cord injury researcher Naomi Kleitman, vice president of research at the Craig H. Nielsen Foundation, who was not involved in the study. "It's a phenomenon, and we need to learn more about how this can happen."
The olfactory ensheathing cells are thought to be special because they communicate between the central and peripheral nervous systems, allowing smell signals to travel directly to the brain, Kleitman said.
They're also known to regenerate, unlike other cells in the central nervous system.
In a video shot before his spinal injection, Jasper walked on the treadmill using only his front legs as his back legs hung limply from a harness. Three months after the treatment, researchers videotaped him walking on all four legs, supported by a harness. The final video was shot six months after treatment, and shows Jasper walking without the harness, stumbling only occasionally. (His tail, of course, never stops wagging.)
But Jasper was fortunate. Many of the dogs had increased automatic function only on a treadmill when they were supported by a harness. None of the dogs that received the nose cells had any adverse health effects.
"It's very difficult to know what this means without the ability to go in and look at the spinal cord histology and see what these transplants managed to do," said Edward Hall, a professor at the University of Kentucky Spinal Cord and Brain Injury Research Center. Since the study subjects are pets, researchers can't kill them and perform autopsies to determine exactly how the nose cells worked in the spinal column.
About 200,000 people in the United States are currently living with spinal cord injury, according to the Centers for Disease Control and Prevention. There are between 12,000 to 20,000 new spinal injury patients each year.
Co-author Robin Franklin said the study is the first to show that the nose cells can repair severely damaged spinal cords, bringing back front-hind leg coordination.
Researchers are still a long way from restoring spinal function in humans, researcher Geoffrey Raisman, chair of Neural Regeneration at University College London, told the BBC. Raisman discovered olfactory ensheathing cells in 1985.
"This is not a cure for spinal cord injury in humans -- that could still be a long way off," Raisman said. "But this is the most encouraging advance for some years and is a significant step on the road toward it."