Canine degenerative myelopathy is a progressive, adult-onset neurodegenerative disease characterized by pelvic limb proprioceptive ataxia that progresses to paraparesis, then paralysis of the pelvic limbs, followed by thoracic limb paralysis. Treatment is limited to palliative therapy due to the lack of effective treatment options. This retrospective study evaluated the effect of 2 photobiomodulation therapy protocols on the progression of clinical signs of degenerative myelopathy. All dogs received the same twice-weekly in-clinic rehabilitation therapy and at-home exercise program. In addition, during in-clinic therapy, dogs received either photobiomodulation therapy protocol A (PTCL-A; n = 6) or photobiomodulation therapy protocol B (PTCL-B; n = 14). Results in the PTCL-B group showed significantly longer times between signs of onset and euthanasia as well as between signs of onset and nonambulatory paresis or paralysis as compared with the PTCL-A group; Kaplan–Meier survival analysis also demonstrated significantly longer time of clinical sign onset to nonambulatory paresis in the PTCL-B group as compared with the PTCL-A group and historical data group. These results suggest there may be potential benefits of using PTCL-B in combination with an intense rehabilitation therapy plan in dogs with degenerative myelopathy. A randomized, double-blinded placebo control prospective clinical trial is underway.