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.
