Coefficients of variation of ground reaction force measurement in cats

Abstract

Gait analysis has been extensively performed in dogs and horses; however, very little is known about feline biomechanics. It was, therefore, the aim of this study to determine the coefficient of variation (CV) among three ground reaction force (GRF) measurements taken for 15 client-owned European shorthaired cats without a training period and a short acclimatisation time. Gait was measured as each cat walked across a pressure-sensitive walkway, and measurements were made three times over a multi-week period (range: 2 to 17 weeks). The parameters evaluated were peak vertical force (PFz), vertical impulse (IFz), stance phase duration (SPD), step length (SL), paw contact area (PCA) and symmetry index (SI%) of the front and hind limbs. After averaging each of the values from the three measurements, the CV and 95% confidence interval (CI) were calculated for all parameters. PFz showed the lowest CV (~ 3%), while IFz showed the highest CV (~11%) when normalised to body mass. When the GRFs were normalised to total force, the CV of PFz dropped to ~2% and that of IFz dropped to ~3%. The CV of SL and PCA were lower (~6% respectively ~5%) compared to the CV for SPD (~10%). The SI% for both PFz and IFz were comparable to the values reported in the gait analysis literature for dogs. Results of the current study indicate that gait analysis of cats using pressure-sensitive walkways produces reliable data and is a promising approach for evaluation of lameness. The results also suggest that PFz may be a more reliable parameter than IFz and that normalisation to percent of total force may aid in interpretation of the evaluated data.

Evaluation of parameters obtained from two systems of gait analysis

“…Force platforms are considered one of the most accurate methods for kinetic gait analysis in dogs, since it allows the evaluation of vertical, mediolateral and craniocaudal ground reaction forces . However, some restrictions of using force platforms have stimulated the use and development of other gait systems, such as the pressure platform and, more recently, the Gait4Dog treadmill…”

“…The system allows obtainment of data regarding stance time (sec) swing time (sec), percentage of stance time, percentage of swing time, stride length (m), gait cycle time (sec), maximum force, vertical impulse, and percentage of body weight distribution . Among the several models of pressure platforms, the pressure walkways are the most commonly used in small animals since they are also suitable for evaluating cats …”

Evaluation of a pressure plate for detection of hind limb lameness in cats

“…Pressure plates are often used to measure temporospatial parameters and GRFs, including PFz (peak vertical force) and IFz (vertical impulse). These measurements have been confirmed to be reliable and comparable from breed to breed [10,11]. Measurement of GRFs (PFz and IFz) can detect lameness in dogs and cats [12][13][14][15].…”

“…Furthermore, cats often adopt a crouched position in the consulting room, making it even more difficult to evaluate gait [4,5]. Much effort has been made to establish objective outcome measurements in cats [6][7][8][9][10][11]. The main advantages of measuring ground reaction force (GRF) are less observer bias (meaning less subjectivity) and the ability to collect and store data [9].…”

“…In recent years, there has been increasing interest in gait analysis in cats [6][7][8][9][10][11]. Pressure plates are often used to measure temporospatial parameters and GRFs, including PFz (peak vertical force) and IFz (vertical impulse).…”