Actical Accelerometers as a Clinical Tool for the Monitoring of Sleeping and Resting Periods in Individual Dogs

Various accelerometers offer to monitor sleep efficiency in dogs, but the underlying proprietary algorithms are not usually revealed. The aim of this pilot study was to achieve insights on the performance of an omnidirectional accelerometer to document sleeping and resting periods in dogs with a simple binary cut-off (0 cpm; ≥1 cpm) and the interference of movements. All data were acquired with a neck collar-mounted accelerometer (Actical^®; Philips Respironics Inc., Murrysville, PA, USA) that provides access to raw data. Ten privately owned dogs (6 dogs with and 4 dogs without movements during sleep) were monitored shortly before, during and after their sleeping and resting periods. Experienced observers documented any visible movement and the corresponding behavioral state continuously for each minute as apparent sleep (eyes closed, regular breathing pattern), rest (eyes open), awake and alert. Total observation time was 2633 min, and 32 sleeping and resting periods were monitored. Zero accelerometer counts per minute documented the combined sleeping and resting periods with a sensitivity of 94.0% and specificity of 96.1% but could not differentiate between apparent sleeping and resting with eyes closed or open. Mild movements during sleep did not interfere with the recordings. The pilot data obtained in this study supports further investigation of this approach to document sleeping and resting periods over prolonged periods in individual dogs.