{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T12:13:56Z","timestamp":1785413636929,"version":"3.56.0"},"reference-count":53,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2026,7,26]],"date-time":"2026-07-26T00:00:00Z","timestamp":1785024000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Pro Pferd, University of Zurich, Switzerland"},{"id":[{"id":"https:\/\/ror.org\/02crff812","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Office of the Director, National Institutes of Health of the National Institutions of Health","award":["T32ODO011000"],"award-info":[{"award-number":["T32ODO011000"]}]},{"name":"National Center for Research Resources or the National Institutes of Health"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Animals"],"abstract":"<jats:p>In human medicine, homocysteine, a sulfur-containing amino acid, is used as a biomarker reflecting endothelial dysfunction, inflammation, thrombogenesis, oxidative stress and cardiovascular disease. An automated enzyme-cycling assay for homocysteine, established for humans, has been validated and reference ranges have been created for horses. In this study the homocysteine assay was further evaluated by assessing short-term stability (whole blood and plasma samples stored at 4 \u00b0C and room temperature for 24 h), long-term stability (two years), the effect of different anticoagulants (lithium heparin, sodium citrate, EDTA, no additives) and repeated freeze\u2013thaw cycles (five times). Further, associations between plasma homocysteine concentrations ([HCY]p) and echocardiographic variables of left heart size, left heart function, and left-sided valve regurgitation were investigated. Homocysteine concentrations remained stable in whole blood at room temperature for at least four hours, or longer when plasma is separated and kept at 4 \u00b0C. Samples could be collected in serum blood tubes, lithium heparin (LH), or EDTA without affecting homocysteine concentrations ([HCY]). Plasma [HCY] in frozen samples increased slightly with storage time (years), though up to five freeze\u2013thaw cycles did not affect [HCY]p. In a cohort of 169 horses with left-sided valvular regurgitation, plasma creatinine concentrations and age were positively associated with higher [HCY]p, but no association between [HCY]p and changes in cardiac size, function or severity of valvular regurgitation could be established. Homocysteine is not associated with left-sided valvular heart disease in horses and is not a useful biomarker for structural or functional cardiac changes.<\/jats:p>","DOI":"10.3390\/ani16152307","type":"journal-article","created":{"date-parts":[[2026,7,27]],"date-time":"2026-07-27T01:26:23Z","timestamp":1785115583000},"page":"2307","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Plasma Homocysteine Concentrations in Horses with Left-Sided Valvular Heart Disease"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0009-0000-0409-7784","authenticated-orcid":false,"given":"Patricia","family":"Egli","sequence":"first","affiliation":[{"name":"Equine Department, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7910-8740","authenticated-orcid":false,"given":"Elizabeth","family":"Williams Louie","sequence":"additional","affiliation":[{"name":"Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Martina","family":"Stirn","sequence":"additional","affiliation":[{"name":"Clinical Laboratory, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5191-5241","authenticated-orcid":false,"given":"Gunther","family":"van Loon","sequence":"additional","affiliation":[{"name":"Equine Cardioteam Ghent, Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8129-2006","authenticated-orcid":false,"given":"Annelies","family":"Decloedt","sequence":"additional","affiliation":[{"name":"Equine Cardioteam Ghent, Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6095-5402","authenticated-orcid":false,"given":"Colin C.","family":"Schwarzwald","sequence":"additional","affiliation":[{"name":"Equine Department, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5545-5630","authenticated-orcid":false,"given":"Katharyn J.","family":"Mitchell","sequence":"additional","affiliation":[{"name":"Equine Department, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland"},{"name":"Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1392","DOI":"10.1515\/CCLM.2003.214","article-title":"DACH-LIGA homocystein (german, austrian and swiss homocysteine society): Consensus paper on the rational clinical use of homocysteine, folic acid and B-vitamins in cardiovascular and thrombotic diseases: Guidelines and recommendations","volume":"41","author":"Stanger","year":"2003","journal-title":"Clin. 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