Researchers in South Korea have envisioned what could be the ultimate foaling alarm for horses, fitted with sensitive accelerometers and altitude sensors, a heart-rate monitor, a thermometer, and technology to track nerve stimulation in muscles.
The study team, writing in the Journal of Animal Reproduction and Biotechnology, monitored pregnant mares to assess changes in behavior in the 90 minutes before their waters broke – the rupture of the amniotic sac.
They observed a range of changes that could be monitored through technology, potentially helping to provide a more robust system to warn caregivers of impending birth.
The researchers, Youngwook Jung, Heejun Jung, Yongseok Jang, Duhak Yoon and Minjung Yoon, stressed the importance of preventing losses of foals and mares.
They noted that analysis work had been done on specific motions for alarm systems, but they want to learn more about wider behavior patterns and their frequency in the key 90-minute window before birth.
Existing systems, in their view, still had pitfalls that have yet to be overcome, and an earlier warning would be more desirable.
For their study, they monitored pre-foaling behaviors in five Thoroughbred mares, aged 9 to 20. They divided the 90-minute period into three half-hour intervals for their analysis. The animals served as their own controls, with data gathered two days before birth used for comparison – what the study team called a normal day.
The researchers in the Kyungpook National University study found that the number of sitting-down and standing-up behaviors was significantly higher in the third 30-minute period compared with that of a normal day, which indicates this behavior is a pre-foaling sign.
» Further reading: Normal signs of behaviour before and including foaling in mares
They noted that a sensitive altitude sensor could be used to detect sitting down and standing up. An accelerometer that senses the three-axis movement of an object could also be used.
Additional typical pre-foaling behaviors should be added to a monitoring system, they said.
A higher number of mares demonstrated pawing behavior in the last 30-minute period compared to a normal day. It is, they said, a behavior linked to frustration, pain, or/and stress, and previous research has shown that the average heart rate increases in horses showing pawing behavior. Also, electromyographic data – electrical activity produced by skeletal muscles – was strictly correlated with heart rate in another study.
Thus, pre-foaling signs could be detected by monitoring changes in mares using heart rate and electromyographic sensors.
Head-lowering behavior was significantly higher in periods two and three – the hour leading up to the waters breaking – in comparison to a normal day. To identify this behavior, altitude and accelerometer sensors should be attached to the halter.
They said a mare lying down to give birth can be easily detected with altitude and accelerometer sensors, but it would be preferable if foaling assistants could be reliably alerted earlier, before the rupture of the amniotic sac.
Foaling alarm systems should be developed to detect pre-foaling behaviors beyond recumbency at the time of birth.
Mares in the 90-minute window also showed abnormal locomotion – what researchers described as a weaving behavior. This also could be monitored by halter-attached altitude and accelerometer sensors.
The authors noted that looking at the belly, known as flank watching, is regarded as a major pre-foaling sign, but in their study, it did not emerge as a significant behavior in the monitored mares.
They noted there was research indicating that body temperature changes were linked to the birth process. A pre-foaling detection device should include a thermometer, they said.
“In conclusion,” they said, “an optimal foaling alarm system should be equipped with altitude and accelerometer sensors as well as heart rate and electromyographic sensors. In addition, the system should be equipped with a thermometer sensor to detect the changes in the temperature of pre-foaling mares.”
Classification of behavioral signs of the mares for prediction of the pre-foaling period. Youngwook Jung, Heejun Jung, Yongseok Jang, Duhak Yoon, and Minjung Yoon. Journal of Animal Reproduction and Biotechnology 2021; 36(2): 99-105 https://doi.org/10.12750/JARB.36.2.99