Associations Between Anesthetic Variables and Functional Outcome in Dogs With Thoracolumbar Intervertebral Disk Extrusion Undergoing Decompressive Hemilaminectomy.

BACKGROUND: Outcome of acute experimental spinal cord injury is strongly associated with tissue perfusion and oxygenation. Cardiopulmonary depression could affect outcome in dogs undergoing general anesthesia for surgical treatment of thoracolumbar intervertebral disk extrusion (IVDE). HYPOTHESIS/OBJECTIVES: To evaluate the effects of general anesthesia on functional outcome in dogs undergoing surgery to treat thoracolumbar IVDE. ANIMALS: Eighty-four client-owned dogs with acute thoracolumbar IVDE treated by decompressive hemilaminectomy. METHODS: Exploratory, retrospective observational study. Medical records were reviewed for clinical presentation and anesthetic monitoring variables, including duration of anesthesia and surgery, hypotension, bradycardia, temperature, and respiratory parameters. Multivariable regression tree analysis was performed to explore associations between anesthetic variables and functional outcome scores after 6 weeks, as well as return to ambulatory status. RESULTS: Episodes of bradycardia (69%) and hypotension (57%) were frequent. Across all outcome measures, regression tree analysis highlighted functional grade at presentation as the primary determining factor, and among pain perception negative dogs, there was a possible association between increased duration of surgery and poorer outcome. In dogs with intact pain perception, duration of bradycardia, mean body temperature, and mean end-tidal carbon dioxide were highlighted. CONCLUSIONS AND CLINICAL IMPORTANCE: Exploratory statistical methods can facilitate hypothesis-generating studies to inform prospective investigations in veterinary medicine. Although the mechanism is uncertain, increased duration of surgery might be associated with poorer outcome in pain perception negative dogs with thoracolumbar IVDE.

Recovery of stepping and coordination in dogs following acute thoracolumbar intervertebral disc herniations.

Prospective data on the recovery of coordination in dogs suffering acute thoracolumbar intervertebral disc herniations (TL-IVDH) are limited. The purpose of this study was to use treadmill based and open field scores (OFS) to quantify recovery of stepping ability and forelimb, hindlimb coordination in the 6 weeks following surgical decompression of dogs with TL-IVDH. Sixty-three dogs were grouped at presentation as grades 3 (non-ambulatory paraparetic), 4 (paraplegic) or 5 (paraplegic without pain sensation) and were evaluated 2, 4, and 6 weeks post-operatively. Stepping scores and Regularity Index (RI), a measure of coordination, were calculated from treadmill walking, and an OFS incorporating supported and unsupported walking was assigned. Outcomes for the three measures were compared between groups and correlation between scoring methods was assessed. Grade 3 and 4 dogs recovered ambulation by 2 weeks, reaching median stepping scores of 96 and 90% by 6 weeks, respectively. Recovery of coordination differed between groups 3 and 4 with median RI scores of 93.9% and 63%, respectively, by 6 weeks. Eight grade 5 dogs failed to recover independent ambulation by 6 weeks. Nine dogs recovered with scores that were significantly worse than the grade 3 and 4 dogs at 6 weeks for stepping score (P < 0.001) and RI (P < 0.001). OFS correlated closely with stepping and RI scores and each group was significantly different using this ordinal scale. In conclusion, recovery of coordination was incomplete in dogs that showed good recovery of stepping. The data generated could be used for clinical trial design.