Age, embryo donor status, and insemination with chilled semen all predispose to persistent breeding-induced endometritis in Warmblood mares

Age, embryo donor status, and insemination with chilled semen all predispose to persistent breeding-induced endometritis in Warmblood mares | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL Equine Veterinary Journal This is a preprint and has not been peer reviewed. Data may be preliminary. 7 October 2025 V1 Latest version Share on Age, embryo donor status, and insemination with chilled semen all predispose to persistent breeding-induced endometritis in Warmblood mares Authors : Tom Stout 0000-0001-5321-8095 [email protected] , Rik Serrarens , Bart Leemans , and Anthony Claes 0000-0003-2209-7598 Authors Info & Affiliations https://doi.org/10.22541/au.175984036.61286740/v1 Published Equine Veterinary Journal Version of record Peer review timeline 207 views 120 downloads Contents Abstract Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Background: Persistent breeding-induced endometritis (PBIE) is a common reason for mares failing to establish pregnancy. Objective: Examine the hypothesis that advancing mare age and embryo donor status predispose to PBIE and compromise fertility. Study design: Retrospective analysis of the impact of mare age, breeding system (embryo donor versus broodmare) and semen type (chilled versus frozen-thawed) on the likelihood of PBIE and subsequent pregnancy/embryo recovery. Methods: Warmblood mares(n=769) inseminated during 1745 oestrous cycles were divided into three age categories (≤ 6, 7-13 and ≥ 14 years) and as embryo donors versus broodmares. PBIE was defined as the detection of >2 cm intrauterine fluid from the day after insemination. Multivariable analysis was used to examine the effect of mare age, breeding system, semen type, inseminated cycle number, ovulation induction, oestrus induction, reproductive status (barren, foaling, maiden), treatment for fluid accumulation (mostly oxytocin and/or uterine lavage) and time of year (month) on the incidence of PBIE and pregnancy/embryo recovery. Results: The likelihood of developing PBIE (27.6% of all cycles) was higher in older mares (≥ 14 years: odds ratio (OR) 7.81) and ET donors (OR 1.58) but reduced in foaling mares (OR 0.14) or when using frozen semen (OR 0.39). Pregnancy or embryo recovery was lower (OR 0.36) for frozen-thawed (39.6%) than chilled-transported (58.3%) semen, and in older mares (OR 0.6), but was improved by ovulation induction (OR 1.5) and not significantly affected by PBIE (p=0.2), suggesting that treatment was usually sufficient to mitigate the negative effects of PBIE. Main limitation: Retrospective data from multi-veterinarian clinic; mare status and pregnancy data missing from some cases. Conclusions: Advancing mare age increases the likelihood of PBIE and compromises fertility; although embryo donor status and chilled semen use increase the odds of PBIE, effects on fertility are minimized by simple treatments. Supplementary Material File (stout.uterine_fluid.evj.anon-blinded.docx) Download 110.92 KB Information & Authors Information Version history V1 Version 1 07 October 2025 Peer review timeline Published Equine Veterinary Journal Version of Record 24 Apr 2026 Published Copyright This work is licensed under a Non Exclusive No Reuse License. Collection Equine Veterinary Journal Authors Affiliations Tom Stout 0000-0001-5321-8095 [email protected] University of Kentucky Maxwell H Gluck Equine Research Center View all articles by this author Rik Serrarens Universiteit Utrecht Faculteit Diergeneeskunde View all articles by this author Bart Leemans Universiteit Utrecht Faculteit Diergeneeskunde View all articles by this author Anthony Claes 0000-0003-2209-7598 Universiteit Utrecht Faculteit Diergeneeskunde View all articles by this author Metrics & Citations Metrics Article Usage 207 views 120 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Tom Stout, Rik Serrarens, Bart Leemans, et al. Age, embryo donor status, and insemination with chilled semen all predispose to persistent breeding-induced endometritis in Warmblood mares. Authorea . 07 October 2025. DOI: https://doi.org/10.22541/au.175984036.61286740/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu . Format Please select one from the list RIS (ProCite, Reference Manager) EndNote BibTex Medlars RefWorks Direct import Tips for downloading citations document.getElementById('citMgrHelpLink').addEventListener('click', function() { popupHelp(this.href); return false; }); $(".js__slcInclude").on("change", function(e){ if ($(this).val() == 'refworks') $('#direct').prop("checked", false); $('#direct').prop("disabled", ($(this).val() == 'refworks')); }); View Options View options PDF View PDF Figures Tables Media Share Share Share article link Copy Link Copied! Copying failed. 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