Today we're going to take a small break from our cranial nerve evaluation to look at the recurrence rate of confirmed and suspected cervical intervertebral disc herniations in dogs with or without prophylactic fenestration. A study published in Veterinary Surgery by Berthome et al detailed the recurrence rate in a group of dogs that received prophylactic fenestration to those that did not.
What is fenestration? Fenestra means “window” in Latin, which is exactly what we’re cutting in the disc. This procedure is performed in dogs with a concurrent Type I disc herniation after removal of the herniated disc. This surgery is performed on the discs that did NOT herniate; thus, it is called prophylactic. During surgery, many neurologists, me included, cut a small window in the outer annulus fibrosis and “scoop” or attempt to remove the nucleus pulposus from the intervertebral disc. Fenestration is supposed to reduce the risk of herniation via three ways: 1) remove of the offending nucleus decrease the amount of material available to herniation. 2) provide a different path of least resistance for the disc to herniation (in the neck this will be ventrally away from the spinal cord) and 3) the scar tissue that forms after mechanical fenestration holds the remaining nucleus pulposus in place.
Results
The study by Berthome et al included 55 dogs, with weights less than 20 kg. Of these 55 dogs, 18 received prophylactic fenestration, and the remaining 37 did not. Neurologic grades were similar between groups, as were surgical sites for the herniated disc. Recurrence was defined as confirmed if advanced imaging was performed and a new disc herniation was noted. It was defined as suspected if clinical signs of new neck pain or worsening gait changes were documented by a veterinarian, but no advanced imaging was performed. A recurrence rate of 25% was noted (14/55) and all 14 dogs were in the non-fenestrated group. Only 1 dog had a confirmed new disc herniation, the remaining 13 were suspected. Surgical times were significantly shorter (p = 0.017) for dogs not undergoing fenestration compared to those that underwent prophylactic fenestration. Complication rates were similar (p=0.838), and no major perioperative complications were found in this study in either group.
Take Home:

Prophylactic cervical disc fenestration may reduce the risk of disc herniation
Srugical times may be longer if prophylactic fenestration is performed, leading to higher anesthetic costs (significance unknown)
Recurrence was not confirmed in most of the cases so take this will a little grain of salt

Reference:DOI: 10.1111/vsu.14303. Vet Surgery J 2025

As I mentioned above, I do fenestration and have been an advocate for this for years. If you perform ventral slot surgeries and are unclear on the fenestration technique let me know; I’d be happy to teach you. Based on this data, hopefully we can reduce the risk of recurrent neck pain on our small dog population that is already over represented with cervical pain!Thanks for reading. I hope you’re staying cool in this summer heat.