Coefficients of variation of ground reaction force measurement in cats.
Authors: Schnabl-Feichter Eva, Tichy Alexander, Bockstahler Barbara
Journal: PloS one
Summary
# Gait Analysis Reliability in Cats: Ground Reaction Force Measurements Pressure-sensitive walkway technology has become invaluable for objective lameness evaluation in dogs and horses, yet feline biomechanics remain poorly characterised—a gap this study addressed by measuring the reproducibility of ground reaction force (GRF) parameters across multiple sessions in 15 untrained domestic cats. The researchers collected GRF data over 2–17 week intervals using a pressure-sensitive walkway, calculating coefficients of variation for six key parameters: peak vertical force (PFz), vertical impulse (IFz), stance phase duration, step length, paw contact area, and symmetry indices. Peak vertical force emerged as the most consistent metric (coefficient of variation ~3% when normalised to body mass, dropping to ~2% when expressed as a percentage of total force), whilst vertical impulse proved more variable (~11%), and stance phase duration showed intermediate variability at approximately 10%. The symmetry indices for vertical forces in cats aligned favourably with established canine reference values, suggesting that pressure-sensitive walkway gait analysis generates sufficiently reliable data for clinical lameness assessment in feline patients. For practitioners considering gait analysis in cats, these findings support the technique's utility; however, prioritising peak vertical force over impulse values and expressing results as a percentage of total force may improve both reproducibility and clinical interpretation.
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Practical Takeaways
- •Pressure-sensitive walkway gait analysis is a valid, repeatable method for detecting lameness in cats and can be performed with minimal acclimatization
- •Peak vertical force is the most reliable single parameter to monitor when assessing feline gait changes; vertical impulse alone should be interpreted cautiously due to higher variability
- •Normalizing force data to percent of total force improves clinical reliability and allows better comparison between individual cats or serial measurements
Key Findings
- •Peak vertical force (PFz) showed the lowest coefficient of variation (~3%), making it the most reliable ground reaction force parameter in cats
- •Vertical impulse (IFz) demonstrated the highest variability (~11% when normalized to body mass, ~3% when normalized to total force)
- •Pressure-sensitive walkway gait analysis produced reliable and reproducible measurements in cats without prior training
- •Normalization to total force rather than body mass improved consistency of force measurements and reliability for clinical interpretation