Relationship Between Mechanical Thresholds and Limb Use in Dogs With Coxofemoral Joint OA-Associated Pain and the Modulating Effects of Pain Alleviation From Total Hip Replacement on Mechanical Thresholds

Objectives: To compare von Frey mechanical quantitative sensory thresholds (mQST_vF) between pelvic limbs in dogs before unilateral total hip replacement (THR) surgery; to correlate ground reaction forces (GRF) with mQST_vF; to assess changes in mQST_vF after THR surgery. Study Design: Prospective clinical study. Animals: Dogs (n=44). Methods: mQST_vF and GRF measured using a pressure sensitive walkway were evaluated before, and 3, 6, and 12 months after, unilateral THR. Measurements were recorded from the affected (operated) pelvic limb (APL) and the non-operated pelvic limb (NPL). Random effects analysis and forwards stepwise linear regression models were used to evaluate the influence of time since surgery and patient factors on mQST_vF thresholds. Results: There were no significant correlations between mQST_vF data and age, bodyweight or the GRF variables. Preoperative mQST_vF measured at the APL and NPL did not differ (P=909). mQST_vF thresholds increased significantly after 12 months in NPL (P=047) and APL (P=001). In addition to time, APL mQST_vF values were significantly affected by sex (higher in males, P=010) and body condition score (higher in leaner dogs, P=035) and NPL mQST_vF values by sex (P=038). Conclusion: Successful unilateral THR results in decreased central sensitization after 12 months.