Comparison of post-surgical complication rates and potential confounding factors in two common approaches for elective altering in female rats (Rattus norvegicus)

Abstract

Elective altering in small mammals is a routine surgery in many exotic companion animal practices. Two techniques, the flank approach (FA), and ventral midline approach (VMA) have been well described in the literature. Flank approach and VMA are utilized for ovariectomy (with or without partial hysterectomy) and ovariohysterectomy respectively. The objective of this study is to compare complication rates between these two approaches as well as identify predictors for adverse events post operatively. A retrospective analysis was performed at a single private practice to compare postoperative complication rates and potential influence of patient related variables for the two approaches for elective reproductive altering in female rats. A total of 457 female rats were included in this study. Elective altering was performed via FA in 396 rats and via VMA in 61 rats. Medical records were reviewed and data analyzed for complications accounting for patient age, weight, and surgeon expertise. Reported complications were grouped by incision-related, mortality within 48 hours postoperatively, and postoperative pathologic findings. To test for normality of continuous data, the Shapiro-Wilk test was used. Binary logistic regression was then performed to identify predictors of adverse events. Complications were noted in 22 of 396 rats (5.6%, 95% CI: 2–6%) undergoing FA and in (9.8%, 95% CI: 3–9.9%) undergoing VMA (difference in proportion: (6.0%, 95% CI: 4.3–8.7%). Pathologic findings were present in 3 of 396 (0.8%, 95% CI: 0.3–2.2%) in the FA group accounting for uterine disease and representing risk of remaining reproductive tissue through this approach. The VMA group had 1 of 61 (1.6%, 95% CI: 0–8.7%) pathologic findings (difference in proportion: 0.1%, 95% CI: 0–0.2%). Through binary outcome analysis via logistic regression, surgeon expertise, patient age, and weight failed to predict complications for both approaches and was not statistically significant. Surgeons should be aware of the advantages and complications of either technique when choosing a surgical approach for female elective altering in rats.