Influence of muscle-sparing lateral thoracotomy on postoperative pain and lameness: A randomized clinical trial

To assess and compare the magnitude of lameness and level of pain after muscle-sparing lateral thoracotomy (MSLT) and standard lateral thoracotomy (SLT) in dogs.

Randomized, blinded, prospective clinical study.

Twenty-eight client-owned dogs.

The latissimus dorsi muscle was retracted in the MSLT group and was transected in the SLT group. Gait was analyzed with a force plate, and the peak vertical force symmetry index (SI) was calculated within 24 hours before surgery, 3 days postoperatively, and 8 to 12 weeks postoperatively. Symmetry index and pain scores as measured by the Glasgow Composite Measure Pain Scale - Short Form were assessed as primary outcome measures.

The SI 3 days postoperatively was lower compared with the preoperative SI value in all dogs, consistent with lameness of the ipsilateral thoracic limb (P < .001). The absolute differences in preoperative and 3-day-postoperative SI provided evidence that this change was 3.1-fold greater after SLT compared with after MSLT (P = .009). Pain scores 1 day after surgery were lower after MSLT (1) compared with after SLT (2.5, P < .001).

Lateral thoracotomies caused postoperative pain and ipsilateral forelimb lameness, and both were reduced by sparing the latissimus dorsi.

Sparing the latissimus dorsi should be considered to decrease immediate postoperative morbidity in dogs undergoing lateral thoracotomy.