Evaluation of Ultrasound for Detection of Changes in Muscle Mass Recovery after Tibial Plateau Leveling Osteotomy in Dogs

Introduction: Manual thigh circumference (TC) measurement has been used as an objective outcome measure for detection of changes in muscle mass. Recently, the accuracy of this method in dogs has been questioned. Advanced imaging (CT or MRI) provides a more objective and reliable outcome measure; however, these techniques are costly and less practical. Hence ultrasonographic (US) evaluation has been suggested as an alternative. The purpose of this study was to compare serial, TC and US measurements for detection of changes in muscle mass in dogs recovering from tibial plateau leveling osteotomy (TPLO).

Materials and Methods: Medium-large breed dogs (n = 7) undergoing pet-owner elected TPLO were enrolled. Manual TC, US, and objective gait analysis were performed at 0, 2, 4 and 8 weeks after surgery. CT-scans, as the gold standard, were compared with TC and US at 0 and 2 weeks. Data W analyzed for main effect of time within modalities and correlations to CT were calculated.

Results: Statistically significant improvement in gait data confirmed continuous improvement in limb function over duration of study. CT-muscle mass significantly decreased at 2 weeks and was significantly related to the US measurement locations ‘proximal, medial muscle to bone distance (p = 0.004; r = 0.81)’ and ‘proximal, lateral muscle to bone distance (p = <0.001; r = 0.82)’. Both US locations detected a significant increase in muscle mass at wk-8 versus wk-2, whereas manual TC measurements did not (p = 0.199).

Discussion/Conclusion: Ultrasound detects muscle mass changes in dogs recovering from TPLO with greater accuracy than manual TC measurements.

Acknowledgement: Funding for this project was provided by Nestlé Purina PetCare.