Percutaneous enzymatic chemonucleolysis of intervertebral disks appears safe and effective in treatment of acute-onset paraparesis and paraplegia in small dogs.

Objective: To investigate the safety and effectiveness of intradiscal chondroitinase injection as a pragmatic treatment for nonambulatory paraparesis and paraplegia in small dogs.

Methods: In this phase 1 clinical trial, dogs presented to 2 university neurology clinics between January 2023 and June 2024 with acute-onset nonambulatory paraparesis or paraplegia occurring within 48 hours before presentation. Included animals weighed < 15 kg and were between 2 and 10 years old, with caregivers who were unable to afford decompressive surgery. Under fluoroscopic guidance, each dog received 1.25 U of chondroitinase ABC into each of 4 consecutive intervertebral disks in the clinically identified lesion location. Recovery was defined as the ability to walk 50 steps without assistance by 4 months after the injection.

Results: 54 dogs were included, with 4 lost to sufficient follow-up. In those with appropriate follow-up, 38 of 40 dogs (proportion, 0.95; 95% CI, 0.83 to 1.00) with intact pain sensation to the hindquarters recovered by a median of 11 days after the intervention, and 4 of 10 dogs (0.4; 95% CI, 0.17 to 0.69) without pain sensation recovered. No adverse effects related to the injection procedure were detected.

Conclusions: In dogs with intact pain perception, this nonsurgical intervention is associated with similar proportion and time to recover as decompressive surgery. Because of the small case number, uncertainty remains regarding the effectiveness of this intervention in dogs in which hindquarter pain perception has been lost.

Clinical relevance: Nonsurgical treatment for presumed disc-associated paresis and paraplegia appears promising. Randomized controlled trials are required for assessment of effectiveness versus decompressive surgery.