Registration of myometrial activity using multiple site electromyography in cyclic mares.

The research paper describes a method for interpreting electromyographic (EMG) data of myometrial electrical activity in horses, which was used to study changes during various stages of the oestrus cycle.

Methodology

• The researchers developed a method to interpret and analyse electromyographic (EMG) data relating to myometrial, or uterus, electrical activity in mares.
• Four pairs of electrodes were surgically implanted in the myometrium of four healthy mares. Sensing points were located at the tip, middle, and base of the left horn and the uterine body.
• These setups enabled the recording and monitoring of the electrical activity using a polygraph machine.
• To facilitate analysis, the collected data were transformed into a digitized form and statistically evaluated.

Analysis and Results

• Three aspects of myometrial electrical activity were examined while a mare was in oestrus and dioestrus: frequency (activity bursts per hour), duration (time from start to end of a burst), and intensity (peaks per minute).
• The activity levels across the different monitored locations in the uterus were compared to assess synchronisation.
• The study found that to make a statistically relevant analysis, a minimum of 3.5 hours of EMG recordings during oestrus and 7 hours during dioestrus are required.
• The results showed variations in the intensity of electrical activity based on where the electrodes were implanted, with the highest activity in the middle of the horn and the lowest in the uterine body.
• It was discovered that the frequency of activity bursts remained constant during oestrus and dioestrus.
• Notably, the duration and intensity of the uterine electrical activity varied depending on the stage of the oestrus cycle. The mean duration of uterine activity burst during dioestrus was significantly shorter compared to that during oestrus.

Conclusion

• The research provides a tangible methodology for recording and analysing myometrial electrical activity in mares.
• The findings provide insight into how the uterus’s electrical activity varies during different stages of the oestrus cycle, which may have implications for understanding and monitoring equine reproductive health.