Quantification of activity in domestic cats (Felis catus) by accelerometry

Accelerometers (Actical® 'Mini Mitter' (MMA)) have been used to assess the activity of domestic cats (Felis catus), and have been validated against measures of observed activity in this species; however, previous validation trials have had very small sample sizes and have not considered inter-individual variation. The present study aimed to quantify the magnitude of inter-individual variation by validating MMAs against observed activity in a larger number of cats. A total of 288 h of concurrent MMA and observed activity data (percentage of time spent active) were collected from 12 cats and assessed using four defined sampling periods: 1 min, 1 h, 6 h and the 1 h moving average at 10 min intervals. There was a strong linear correlation (P < 0.001) between MMA and observed activity data for the combined data set for all four sampling periods; however, there was considerable variation between cats. The MMA and observed activity data of individual cats were also highly correlated over the 10 min (range of Pearson's correlations: 0.65-0.98, P < 0.001), 1 h (0.68-1.0, P < 0.001), 6 h (0.92-1.0, P < 0.05, except for cat 12 where P > 0.05) and 1 h moving average (0.81-0.99, P < 0.001) sampling intervals. The 1 h moving average at 10 min intervals appeared to be the best sampling interval as it maximised the strength of the correlation while maintaining sufficient information to follow patterns of activity over the 24 h. Ultimately, the current study showed that MMAs can be used to accurately quantify the activity of domestic cats; however, there was a considerable amount of variation between cats, and thus each cat should be considered independently and serve as their own control when assessing any changes in activity levels.