Scientists restored movement to the dogs' legs by bridging breaks in the spinal cord using cells taken from their noses.
The trial is the first to demonstrate effective spinal cord repair in "real life" injury cases.
Robin Franklin, of Cambridge University, said: "Our findings are extremely exciting because they show for the first time that transplanting these types of cell into a severely damaged spinal cord can bring about significant improvement."
For a decade, experts have known that olfactory ensheathing cells (OECs) might prove useful in treating damaged spinal cords. Scientists studied 34 pet dogs that had all suffered spinal cord injuries.
One group of dogs had OECs taken from the lining of their own noses and injected into the injury site. Significant improvement was seen in the dogs injected with OECs.