Increase of body temperature immediately after ovulation in mares

While this at first glance looks like useful information the conclusion is the important info: “… the identified temperature rise is relatively small on average and hardly identifiable in the individual mares.”
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Increase of body temperature immediately after ovulation in mares
J Equine Vet Sci. 2023 May 18;104565.
Authors
Pascale Epper 1 , Stefan Glüge 2 , Beatriz Vidondo 3 , Anna Wróbel 2 , Thomas Ott 2 , Harald Sieme 4 , Rebekka Kaeser 1 , Dominik Burger 5
Affiliations

1 Swiss Institute of Equine Medicine, Vetsuisse Faculty University of Bern, Les Longs-Prés, 1580 Avenches, Switzerland.
2 ZHAW Zurich University of Applied Sciences, 8820 Wädenswil, Switzerland.
3 Veterinary Public Health Institute, University of Bern, Schwarzenburgstrasse 161, 3097 Liebefeld, Switzerland.
4 Clinic for Horses – Unit for Reproductive Medicine, University of Veterinary Medicine Hannover, Bünteweg 2, 30559 Hannover, Germany.
5 Swiss Institute of Equine Medicine, Vetsuisse Faculty University of Bern, Les Longs-Prés, 1580 Avenches, Switzerland. Electronic address: dominik.burger@vetsuisse.unibe.ch.

PMID: 37209788
DOI: 10.1016/j.jevs.2023.104565

Abstract

To successfully inseminate mares, precise detection of ovulation time is crucial, especially when using frozen-thawed semen. Monitoring body temperature, as has been described in women, could be a non-invasive way to detect ovulation. The objective of this study was to investigate the relationship between the time of ovulation and the variation of body temperature in mares based on automatic continuous measurements during estrus. The experimental group included 21 mares for 70 analyzed estrous cycles. When the mares showed estrous behavior, they were administered intramuscular deslorelin acetate (2.25 mg) in the evening. At the same time, monitoring of body temperature using a sensor device fixed at the left lateral thorax was started and continued for over 60 h. In 2-hour intervals, transrectal ultrasonography was performed to detect ovulation. Estimated body temperature in the 6 h following ovulation detection was on average 0.06°C +/- 0.05°C (mean +/- SD) significantly higher when compared with body temperature at the same time on the preceding day (p=0.01). In addition, a significant effect of PGF2α administration for estrus induction on the body temperature was found, being significantly higher until 6 h before ovulation compared to that of uninduced cycles (p=0.005). In conclusion, changes in body temperature during estrus in mares were related to ovulation. The increase in body temperature immediately after ovulation might be used in the future to establish automatized and non-invasive systems to detect ovulation. However, the identified temperature rise is relatively small on average and hardly identifiable in the individual mares.

Keywords: body temperature; estrus; horse; mare; ovulation.