Association of uterine edema with follicle waves around the onset of the breeding season in pony mares.
Abstract: During spring transition, when estrus may be exhibited for prolonged periods, it is important for veterinarians and stud farm personnel to be able to predict whether a large follicle will ovulate or regress. It is thought that the presence of ultrasonically detectable uterine edema indicates that a follicle will ovulate, however, there is little evidence to support this. In the present study, 16 mares were regularly examined by transrectal ultrasonography to follow growth and regression of follicles from seasonal anestrus in February until second ovulation. Blood samples were collected daily for measurement of estradiol concentrations when a large ovarian follicle was present. Estrous-like uterine edema was detected during 7 of 11 (64%) anovulatory follicle waves, in 12 of 14 (86%) mares before their first ovulation, and in 100% of mares before their second ovulation. Uterine edema was first detected 43+/-6.7 days before first ovulation. Large anovulatory follicles tended to be present for longer periods of time than ovulatory follicles. Uterine edema was present for a significantly greater proportion of time in the presence of a large follicle at second ovulation than at first ovulation (P<0.05) or for anovulatory follicles (P<0.01). Peak plasma estradiol concentrations and mean plasma estradiol concentrations were significantly higher (P<0.001) when a dominant preovulatory follicle was present compared with a dominant anovulatory follicle, but there was no difference in estradiol concentrations between first and second ovulations. It was apparent, therefore, that uterine edema was not a reliable indicator of follicular steroidogenic competence, or of whether the follicle would ovulate.
Publication Date: 2003-01-16 PubMed ID: 12527066DOI: 10.1016/s0093-691x(02)01161-5Google Scholar: Lookup
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- Comparative Study
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research article investigates the association between the presence of uterine edema and the likelihood of follicle ovulation in pony mares at the onset of the breeding season. The findings suggest that uterine edema, detectable via ultrasonography, is not a reliable predictor of whether a follicle will ovulate.
Methodology
- The study involved the examination of 16 pony mares using transrectal ultrasonography. This procedure was done to monitor the growth and regression of follicles, starting from seasonal anestrus in February up until the occurrence of the second ovulation.
- Daily blood samples were collected whenever a large ovarian follicle was detected. These samples were specifically used for the measurement of estradiol concentrations.
Findings
- During the tracking period, estrous-like uterine edema was observed during 64% of anovulatory follicle waves, in 86% of mares prior to the first ovulation, and in all mares before the occurrence of the second ovulation.
- Uterine edema manifested initially on average 43+/-6.7 days before the first ovulation.
- It was found that anovulatory follicles stayed longer in comparison to ovulatory follicles.
- The presence of uterine edema was noted significantly for a longer time when a large follicle was at the second ovulation than at the first ovulation or with anovulatory follicles.
- The peak and average plasma estradiol concentrations were significantly higher when a dominant preovulatory follicle was present in contrast to when a dominant anovulatory follicle was present. However, there was no observed difference in estradiol levels between the first and second ovulations.
Conclusion
- The conclusion made from this study indicates that uterine edema is not a reliable predictor of the follicle’s ability to produce steroids, or whether the follicle will undergo ovulation.
- This has important implications for stud farm personnel and veterinarians as they must rely on other indicators to accurately predict ovulation in pony mares during the breeding season.
Cite This Article
APA
Watson ED, Thomassen R, Nikolakopoulos E.
(2003).
Association of uterine edema with follicle waves around the onset of the breeding season in pony mares.
Theriogenology, 59(5-6), 1181-1187.
https://doi.org/10.1016/s0093-691x(02)01161-5 Publication
Researcher Affiliations
- Department of Veterinary Clinical Studies, Easter Bush Veterinary Centre, University of Edinburgh, Easter Bush, Roslin, Midlothian EH25 9RG, UK. elaine.watson@ed.ac.uk
MeSH Terms
- Animals
- Breeding
- Edema / diagnostic imaging
- Edema / veterinary
- Estradiol / blood
- Estrus Detection / methods
- Female
- Horses / physiology
- Ovarian Follicle / diagnostic imaging
- Ovarian Follicle / physiology
- Seasons
- Ultrasonography
- Uterus / diagnostic imaging
- Uterus / physiology
Citations
This article has been cited 3 times.- Miki W, Oniyama H, Takeda N, Kimura Y, Haneda S, Matsui M, Taya K, Nambo Y. Effects of a single use of the GnRH analog buserelin on the induction of ovulation and endocrine profiles in heavy draft mares. J Equine Sci 2016;27(4):149-156.
- Lemma A, Schwartz HJ, Bekana M. Application of ultrasonography in the study of the reproductive system of tropical jennies (Equus asinus). Trop Anim Health Prod 2006 May;38(4):267-74.
- Barbosa LA, Maran AP, de Almeida MER, Guimarães EC, Bringel B, Douglas RH, Lima TFG, da Silva ESM. Plasma Estradiol and Endometrial Edema Profile in Acyclic Mares After Single Administration of 17-β Estradiol, Estradiol Benzoate and Estradiol Cypionate. Reprod Domest Anim 2025 Aug;60(8):e70108.
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