JAVMA, Vol 238, No. 12, June 15, 2011 Scientific Reports 1593 SMALL ANIMALS T horacolumbar IVDH is a common surgical disease of small and chondrodystrophic breeds. Surgical de- compression with removal of extruded disk material is a well-accepted treatment for patients with any severity of clinical signs. 1–6 Fenestration of the affected disk space at the time of decompressive surgery of the spinal cord is rec- ommended to prevent continued extrusion of degenerate disk material through the ruptured annulus fibrosus in the early postoperative period. 1,6–9 A recent study 9 in which magnetic resonance imaging was repeated immediately af- Comparison of the effect of single-site and multiple-site disk fenestration on the rate of recurrence of thoracolumbar intervertebral disk herniation in dogs Brigitte A. Brisson, DMV, DVSc, DACVS; David L. Holmberg,† DVM, MVetSc, DACVS; Joane Parent, DMV, MVetSc, DACVIM; William C. Sears, MS, MSc; Sara E. Wick, MSc, DVM Objective—To prospectively assess whether multiple-site disk fenestration decreases the incidence of recurrent thoracolumbar intervertebral disk herniation (IVDH), compared with single-site disk fenestration, in small-breed dogs treated for IVDH. Design—Randomized controlled clinical trial. Animals—207 client-owned dogs. Procedures—Dogs undergoing decompressive surgery of the spinal cord because of thora- columbar IVDH between 2001 and 2004 were randomly assigned to receive single-site disk fenestration at the level of surgical decompression (n = 103) or multiple-site disk fenestra- tion of all disks from T11 through L4 (104). Follow-up consisted of complete reevaluation of patients, telephone surveys, and further surgery if signs indicative of recurrence occurred. Results—189 dogs were available for long-term follow-up: 95 dogs in the single-site disk fenestration group and 94 in the multiple-site disk fenestration group. Twenty-four dogs developed 28 confirmed episodes of recurrent thoracolumbar IVDH. The rate for first-time recurrence was 12.7% (24/189). First-time recurrence rates for single- and multiple-site disk fenestration groups were 17.89% (17/95) and 7.45% (7/94), respectively. Dogs undergoing single-site disk fenestration were significantly more likely to have recurrent thoracolumbar IVDH than were dogs undergoing multiple-site disk fenestration. Disk mineralization at the time of first surgery was associated with recurrence, and 87.5% (21/24) of recurrences oc- curred at a disk space adjacent to or 1 disk away from the initial lesion. Regardless of disk fenestration group, 22 of 24 (91.7%) recurrences occurred at a nonfenestrated disk space. Conclusions and Clinical Relevance—Multiple-site disk fenestration decreased the rate of recurrent IVDH in small-breed dogs, compared with the use of single-site disk fenestra- tion. (J Am Vet Med Assoc 2011;238:1593–1600) ter and at 6 weeks after surgery confirmed further IVDH at the site of surgery in 6 of 10 dogs that did not undergo fenestration of the affected disk space at the time of surgi- cal decompression. Three of 6 patients had clinical signs (pain, paresis, or both) consistent with the recurrent ex- truded disk material, as observed on magnetic resonance images. 9 Early recurrences reportedly occur within 4 to 6 weeks of surgery and are generally related to extrusion of the nucleus pulposus at the site of initial IVDH. 9–11 The efficacy of prophylactic disk fenestration to pre- vent future herniation at nonaffected disk spaces remains controversial. Published information suggests recurrence rates of 0% to 24.4% with prophylactic disk fenestration 12–17 and 2.67% to 41.7% without prophylactic disk fenestra- tion. 1,4,6,10,14,15,18,19 Retrospective evaluations have shown that late recurrent IVDH occurs at a mean time of 8 to 14 From the Departments of Clinical Studies (Brisson, Holmberg) and Population Medicine (Sears), Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada; the Département de Sciences Cliniques, Faculté de Médecine Vétérinaire, Université de Montréal, St-Hyacinthe, QC J2S 2M2, Canada (Parent); and C.A.R.E. Centre Ani- mal Hospital, 7140 12th St SE, Calgary, AB T2H 2Y4, Canada (Wick). Supported by the Ontario Veterinary College Pet Trust. Presented as an oral presentation at the 27th Annual Forum of the Amer- ican College of Veterinary Internal Medicine, Montreal, June 2009; at the 2010 American College of Veterinary Surgeons Veterinary Sympo- sium, Seattle, October 2010; and at the European College of Veterinary Surgeons 19th Annual Scientific Meeting, Helsinki, July 2010. The authors thank Kathryn Gyselinck for technical assistance. Address correspondence to Dr. Brisson (bbrisson@uoguelph.ca). †Deceased. ABBREVIATIONS CI Confidence interval IVDH Intervertebral disk herniation OR Odds ratio OVCHSC Ontario Veterinary College Health Sciences Center Unauthenticated | Downloaded 02/13/24 12:16 PM UTC