Evaluation of foetal and maternal heart rate and heart rate-variability in Hungarian Lipizzaner broodmares

Fifteen pregnant broodmares and their foetuses have been evaluated with a holter ECG (Televet 100 (R) Engel Engeneering Services, Heusenstamm, Germany) in order to perform a heart rate variability analysis and to establish physiological reference values for foetal heart rate during pregnancy, time-domain (foetuses) and time- and frequency-domain (mares) heart rate variability analysis were performed. Foetal heart rate decreased significantly during pregnancy from 115 +/- 4bpm to 79 +/- 9bpm (mean +/- SD); foetal RR-intervals tended to increase and maternal RR-intervals tended to decrease with ongoing pregnancy as described before, but other parameters (standard deviation of foetal heart rate, maternal standard deviation of normal-normal intervals, root mean square of successive differences and low frequency/high frequency ratio) differed from the available international reference values. In mares, SDNN decreased from 280 +/- 91ms (5th month) to 89 +/- 34ms (11th month) and RMSSD values decreased from 296 +/- 96ms to 96 +/- 57ms. In conclusion, this foetomaternal ECG equipment is a reliable technique to detect foetal cardiac signals and to get valuable information about the well-being of the equine foetus as well as the mare, but further studies are warranted to reveal the reason for contradicting data compared to previous studies.