Detection of the time of foaling by accelerometer technique in horses (Equus caballus)-a pilot study

Observation of preparturient mares is labour-intensive and time requirements would be reduced with automated monitoring systems. Recently, small-size accelerometers have become available. We followed the hypothesis that increased restlessness in mares shortly before the expulsive stage of labour can be detected with such accelerometers. Accelerometers were attached medioventrally to the halter of eight late pregnant mares. To evaluate an influence of accelerometer position, in one mare two additional accelerometers were attached close to the mandibular and atlanto-occipital joints. Accelerometers were programmed to send 600 signals/min (10 Hz). Signals were recorded continuously and, for evaluation, four intervals of 30-min duration on day 4 before foaling and the last 2 hr before rupture of the allantochorion at foaling were selected. Signal detection was influenced by position of the accelerometer on the mares' halter. The highest signal detection rate was reached with the accelerometer in the lateral and dorsal position but differences of accelerations measured by the system differed neither between sensor positions nor between time intervals 4 days before foaling. Differences of accelerations increased from 120 min before foaling until birth of the foal (p < 0.001) and this increase was most pronounced during the last 30-20 min before birth of the foal (p < 0.001). Technical improvements and a foaling specific algorithm are required to improve the accuracy to predict foaling. Even if this preliminary study included only a small number of mares, results demonstrate that accelerometers could be an important component of birth alert systems in horses in the future.