Effects of perineural dexmedetomidine combined with ropivacaine on postoperative methadone requirements in dogs after tibial plateau levelling osteotomy: a two-centre study.

OBJECTIVE: To evaluate the efficacy of a perineural injection of dexmedetomidine combined with ropivacaine for reducing postoperative methadone requirements in dogs after tibial plateau levelling osteotomy (TPLO). STUDY DESIGN: A prospective, clinical, randomized and blinded trial. ANIMALS: A total of 58 client-owned dogs. METHODS: Ultrasound-guided midfemoral sciatic and inguinal femoral nerve blocks with ropivacaine (1 mg kg-1 per nerve block) combined with either dexmedetomidine (0.5 µg kg-1 per nerve block; group DEX) or the same volume of saline (group CON) were performed in dogs undergoing TPLO. Pain was assessed 30 minutes, 2 hours and then every 4 hours for 24 hours after surgery with a validated pain scale (4AVet). Meloxicam (0.15 mg kg-1) was administered intravenously (IV) at recovery. Rescue methadone (0.2 mg kg-1 IV) was administered if a score ≥ 6 (maximal score 18) was recorded and the number of postoperative doses was analysed by Fisher exact tests. The study was performed in parallel at a Veterinary Teaching Hospital (VTH) and a private Veterinary Referral Centre (VRC). RESULTS: Dogs received a total of 22 and 31 postoperative doses of methadone in groups DEX (14 doses at VRC, eight doses at VTH) and CON (28 doses at VRC, three doses at VTH), respectively. Overall, there was no difference in the postoperative rescue analgesia requirements between groups (p = 0.244). At the VRC, dogs received less methadone (p = 0.026) in group DEX compared with group CON, whereas at the VTH, there was no difference between groups (p = 0.216). CONCLUSIONS AND CLINICAL RELEVANCE: Perineural dexmedetomidine combined with ropivacaine did not reduce postoperative methadone requirements in dogs after TPLO, but results may differ from one centre to another. This discrepancy might be linked to variations in clinical practices and questions the validity of results obtained from single-centre randomized controlled trials but applied to different clinical settings.

Comparison of the biomechanical performance of a customized unilateral locking compression plate with and without an intervertebral spacer applied to the first and second lumbar vertebrae after intervertebral diskectomy in canine cadaveric specimens.

OBJECTIVE: To determine whether a customized unilateral intervertebral anchored fusion device combined with (vs without) an intervertebral spacer would increase the stability of the L1-L2 motion segment following complete intervertebral diskectomy in canine cadaveric specimens. SAMPLE: Vertebral columns from T13 through L3 harvested from 16 skeletally mature Beagles without thoracolumbar disease. PROCEDURES: Complete diskectomy of the L1-2 disk was performed in each specimen. Unilateral stabilization of the L1-L2 motion segment was performed with the first of 2 implants: a unilateral intervertebral anchored fusion device that consisted of a locking compression plate with or without an intervertebral spacer. The resulting construct was biomechanically tested; then, the first implant was removed, and the second implant was applied to the contralateral side and tested. Range of motion in flexion and extension, lateral bending, and torsion was compared among intact specimens (prior to diskectomy) and constructs. RESULTS: Compared with intact specimens, constructs stabilized with either implant were as stable in flexion and extension, significantly more stable in lateral bending, and significantly less stable in axial rotation. Constructs stabilized with the fusion device plus intervertebral spacer were significantly stiffer in lateral bending than those stabilized with the fusion device alone. No significant differences in flexion and extension and rotation were noted between implants. CONCLUSIONS AND CLINICAL RELEVANCE: Findings did not support the use of this customized unilateral intervertebral anchored fusion device with an intervertebral spacer to improve unilateral stabilization of the L1-L2 motion segment after complete L1-2 diskectomy in dogs.