FREE SHIPPING over $40
OVER 9000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Home / Equine Research Bank / J Mol Cell Cardiol Plus / Performance horses as a model for exercise-associated cardia...
Journal of molecular and cellular cardiology plus2025; 12; 100452; doi: 10.1016/j.jmccpl.2025.100452

Performance horses as a model for exercise-associated cardiac arrhythmias and sudden cardiac death.

Abstract: This paper reviews the myocardial substrate of horses relative to that of humans and discusses the utility of performance horses as a model of exercise-associated cardiac arrhythmias and sudden cardiac death in athletes. The coronary circulation is similar between the species while coronary artery anomalies and myocardial bridging appear to only be associated with athletic mortality in human athletes and not in performance horses. There are subtle differences in the histology of the sinus and atrioventricular nodes, of unknown clinical significance, while the His bundle is more highly innervated in horses. The equine Purkinje network is much more extensive, contributing to a difference in the mean electrical axis between horses and humans. Differences in ion channel expression have been reported, although they are poorly characterized, and are of unknown clinical significance. However, horses may be a particularly good model to investigate the function of Kv1.5 due to its spontaneous ventricular expression, which is lacking in human ventricles. Similarities in cardiac structure, coronary vasculature, and ability to exercise at high levels makes performance horses a good model to investigate exercise-associated cardiac arrhythmias and sudden cardiac death in athletes. However, differences in myocardial substrate should be taken into consideration when designing studies and interpreting results.
Crown Copyright © 2025 Published by Elsevier Ltd.
Get Full Text
Publication Date: 2025-05-09 PubMed ID: 40475708PubMed Central: PMC12137179DOI: 10.1016/j.jmccpl.2025.100452Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
LinkedInCopy
  • Journal Article
  • Review

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research article investigates the use of performance horses as a model to study exercise-related heart rhythm abnormalities and sudden cardiac deaths in athletes. The study underscores their anatomical similarities with human athletes, corroborated by subtle differences in the structure of heart tissues, ion channel expressions, myocardial substrates, and the nature of arrhythmic risk under strenuous physical activity.

Anatomical Comparisons

  • The article emphasizes the similarities in cardiac structure and coronary vasculature between horses and humans. The coronary circulation patterns are somewhat parallel between the two, providing a reliable comparison foundation.
  • However, the study notes differences such as coronary artery anomalies and myocardial bridging which are linked to mortalities in human athletes but not in performance horses.

Heart Tissue and Ion Channels

  • There exist subtle variations in the histology of the sinus and atrioventricular nodes between the two species. The study flags these as areas of unknown clinical significance, calling for further investigation.
  • It is noteworthy that the His bundle in the cardiac system is more highly innervated in horses, highlighting a crucial difference.
  • The equine Purkinje network, responsible for impulse conduction in the heart, is more extensive than in humans.
  • Furthermore, the mean electrical axis, indicating the general direction of the heart’s electrical drive differs between the two.
  • The ion channel expressions that regulate the flow of ions across the cell membranes, though poorly characterized, show variances.
  • Intriguingly, the Kv1.5 ion channel expression in horses’ ventricles, which is absent in humans’, presents horses as a valuable model for understanding its function.

Myocardial Substrate

  • The differences in myocardial substrate – the muscle tissue in the heart that contributes to contractions and relaxation during the cardiac cycle – is another area that needs to be taken into account when designing studies and interpreting results.

Conclusion

  • In the end, the study brings to the surface that despite their differences, the similarities in heart structure, coronary vasculature, and the ability to undertake strenuous exercise positions performance horses as a useful model to understand exercise-linked cardiac arrhythmias and sudden cardiac death in human athletes.

Cite This Article

APA
Avison A, Physick-Sheard PW, Pyle WG. (2025). Performance horses as a model for exercise-associated cardiac arrhythmias and sudden cardiac death. J Mol Cell Cardiol Plus, 12, 100452. https://doi.org/10.1016/j.jmccpl.2025.100452

Publication

Journal of molecular and cellular cardiology plus
ISSN: 2772-9761
NlmUniqueID: 9918470779706676
Country: England
Language: English
Volume: 12
Pages: 100452
PII: 100452

Researcher Affiliations

Avison, Amanda
  • Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Canada.
Physick-Sheard, Peter W
  • Department of Population Medicine, Ontario Veterinary College, University of Guelph, Canada.
Pyle, W Glen
  • IMPART Team Canada, Dalhousie Medicine, Dalhousie University, Canada.
  • Women's Health Research Institute, BC Women's Hospital + Health Centre, Canada.

Conflict of Interest Statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

References

This article includes 60 references
  1. Corrado D, Basso C, Rizzoli G, Schiavon M, Thiene G. Does sports activity enhance the risk of sudden death in adolescents and young adults?. J Am Coll Cardiol 2003;42(11):1959–1963.
    doi: 10.1016/j.jacc.2003.03.002pubmed: 14662259google scholar: lookup
  2. Physick-Sheard P.W., Slack J. Irregular hearts and performance horses. Equine Vet J 2020;52(6):782–786.
    doi: 10.1111/evj.13316pubmed: 33017494google scholar: lookup
  3. Rosanowski S.M., Chang Y.-M., Stirk A.J., Verheyen K.L.P.. Risk factors for race-day fatality in flat racing thoroughbreds in Great Britain (2000 to 2013). PloS One 2018;13(3):1–12.
    doi: 10.1371/journal.pone.0194299pmc: PMC5862470pubmed: 29561898google scholar: lookup
  4. Physick-Sheard P.W., Avison A., Chappell E., MacIver M. Ontario Racehorse Death Registry, 2003-2015: descriptive analysis and rates of mortality. Equine Vet J 2019;51(1):64–76.
    doi: 10.1111/evj.12955pubmed: 29672910google scholar: lookup
  5. Gibson M.J., Legg K.A., Gee E.K., Rogers C.W. The reporting of racehorse fatalities in New Zealand Thoroughbred flat racing in the 2011/12–2021/22 seasons. Animals 2023;13(4):612.
    doi: 10.3390/ani13040612pmc: PMC9951738pubmed: 36830402google scholar: lookup
  6. Allen S.E., Rosanowski S.M., Stirk A.J., Verheyen K.L.P.. Description of veterinary events and risk factors for fatality in National Hunt flat racing Thoroughbreds in Great Britain (2000-2013). Equine Vet J 2017;49(6):700–705.
    doi: 10.1111/evj.12676pubmed: 28235142google scholar: lookup
  7. Boden L.A., Anderson G.A., Charles J.A., Morgan K.L., Morton J.M., Parkin T.D.H.. Risk of fatality and causes of death of Thoroughbred horses associated with racing in Victoria, Australia: 1989-2004. Equine Vet J 2006;38(4):312–318.
    doi: 10.2746/042516406777749182pubmed: 16866197google scholar: lookup
  8. Lyle C.H., Uzal F.A., McGorum B.C., Aida H., Blissitt K.J., Case J.T.. Sudden death in racing Thoroughbred horses: an international multicentre study of post mortem findings. Equine Vet J 2011;43(3):324–331.
    doi: 10.1111/j.2042-3306.2010.00164.xpubmed: 21492210google scholar: lookup
  9. DeLay J. Postmortem findings in Ontario racehorses, 2003–2015. J Vet Diagn Invest 2017;29(4):457–464.
    doi: 10.1177/1040638717700690pubmed: 28382856google scholar: lookup
  10. Molesan A., Wang M., Sun Q., Pierce V., Desideri R., Palmer S.. Cardiac pathology and genomics of sudden death in racehorses from New York and Maryland racetracks. Vet Pathol 2019;56(4):576–585.
    doi: 10.1177/0300985819829529pubmed: 30917748google scholar: lookup
  11. Nath L., Stent A., Elliott A., La Gerche A., Franklin S. Risk factors for exercise-associated sudden cardiac death in Thoroughbred racehorses. Animals 2022;12(10):1297.
    doi: 10.3390/ani12101297pmc: PMC9137751pubmed: 35625143google scholar: lookup
  12. Gelberg H.B., Zachary J.F., Everitt J.I., Jensen R.C., Smetzer D.L. Sudden death in training and racing Thoroughbred horses. J Am Vet Med Assoc 1985;187(12):1354–1356.
    doi: 10.2460/javma.1985.187.12.1354pubmed: 4086352google scholar: lookup
  13. Physick-Sheard P.W., McGurrin M.K.J. Ventricular arrhythmias during race recovery in Standardbred racehorses and associations with autonomic activity. J Vet Intern Med 2010;24(5):1158–1166.
    doi: 10.1111/j.1939-1676.2010.0553.xpubmed: 20584140google scholar: lookup
  14. Semin K., Iv A.C.S., Heelan K., Brown G.A., Shaw B.S., Shaw I. Discrepancy between training, competition and laboratory measures of maximum heart rate in NCAA division 2 distance runners. J Sports Sci Med 2008;7(4):455–460.
    pmc: PMC3761916pubmed: 24149950
  15. Hinchcliff K., Geor R.J.. The horse as an athlete: a physiological overview. In: Equine Exercise Physiology. Hinchcliff K., Geor R.J., Kaneps A.J., editors. Elsevier; Philadelphia, PA: 2008; pp. 2–11.
    doi: 10.1016/B978-070202857-1.50003-2google scholar: lookup
  16. Kjeldsen S.T., Nissen S.D., Buhl R., Hopster-Iversen C. Paroxysmal atrial fibrillation in horses: pathophysiology, diagnostics and clinical aspects. Animals 2022;12(6):698.
    doi: 10.3390/ani12060698pmc: PMC8944606pubmed: 35327097google scholar: lookup
  17. Guasch E., Mont L., Sitges M. Mechanisms of atrial fibrillation in athletes: what we know and what we do not know. Neth Heart J 2018;26(3):133–145.
    doi: 10.1007/s12471-018-1080-xpmc: PMC5818379pubmed: 29411287google scholar: lookup
  18. Aricatt D.P., Prabhu A., Avadhani R., Subramanyam K., Manzil A.S., Ezhilan J.. A study of coronary dominance and its clinical significance. Folia Morphol 2023;82(1):102–107.
    doi: 10.5603/FM.a2022.0005pubmed: 35099044google scholar: lookup
  19. Gómez F.A., Ballesteros L.E., Estupiñán H.Y. Morphologic expression of the right coronary artery in horses. Comparative description with humans, pigs and other animal species. Austral J Vet Sci 2017;49(3):161–166.
    doi: 10.4067/S0719-81322017000300161google scholar: lookup
  20. Gentile F., Castiglione V., De Caterina R. Coronary artery anomalies. Circ 2021;144(12):983–996.
    doi: 10.1161/CIRCULATIONAHA.121.055347pubmed: 34543069google scholar: lookup
  21. Karlstam E., Ho S.Y., Shokrai A., Ågren E., Michaëlsson M. Anomalous aortic origin of the left coronary artery in a horse. Equine Vet J 1999;31(4):350–352.
    doi: 10.1111/j.2042-3306.1999.tb03830.xpubmed: 10454098google scholar: lookup
  22. Diab S.S., Poppenga R., Uzal F.A. Sudden death in racehorses: postmortem examination protocol. J Vet Diagn Invest 2017;29(4):442–449.
    doi: 10.1177/1040638716687004pubmed: 28114865google scholar: lookup
  23. Bertho E., Gagnon G. A comparative study in three dimension of the blood supply of the normal interventricular septum in human, canine, bovine, porcine, ovine and equine heart. Dis Chest 1964;46(3):251–262.
    doi: 10.1378/chest.46.3.251pubmed: 14206348google scholar: lookup
  24. De Giorgio F., Grassi V.M., Polacco M., Pascali V.L., d’Aloja E., Arena V. Myocardial bridging and sudden cardiac death: is the actual classification exhaustive?. Int J Cardiol 2014;172(3):e383–e384.
    doi: 10.1016/j.ijcard.2013.12.286pubmed: 24508108google scholar: lookup
  25. Möhlenkamp S., Hort W., Ge J., Erbel R. Update on myocardial bridging. Circ 2002;106(20):2616–2622.
    doi: 10.1161/01.CIR.0000038420.14867.7Apubmed: 12427660google scholar: lookup
  26. Gómez F.A., Ballesteros L.E., Estupiñan H.Y. Morphological characterization of the left coronary artery in horses. Comparative analysis with humans, pigs, and other animal species. Ital J Anat Embryol 2017;122(2):137–146.
  27. Saminathan S., Selvaraj V. A cadaveric study of the myocardial bridges. J Evolution Med Dent Sci 2019;8(2):133–136.
    doi: 10.14260/jemds/2019/29google scholar: lookup
  28. Gómez-Torres F.A., Ballesteros-Acuña L.E., Ruíz-Sauri A. Histological and morphometric study of the components of the sinus and atrioventricular nodes in horses and dogs. Res Vet Sci 2019;126:22–28.
    doi: 10.1016/j.rvsc.2019.08.001pubmed: 31421508google scholar: lookup
  29. Ho S.Y., Sánchez-Quintana D. Anatomy and pathology of the sinus node. J Interv Card Electrophysiol 2016;46(1):3–8.
    doi: 10.1007/s10840-015-0049-6pubmed: 26319648google scholar: lookup
  30. Buchanan J.W. Spontaneous arrhythmias and conduction disturbances in domestic animals. Ann N Y Acad Sci 1965;127(1):224–238.
    doi: 10.1111/j.1749-6632.1965.tb49405.xpubmed: 5217261google scholar: lookup
  31. Van Loon G., Patteson M. Electrophysiology and arrhythmogenesis. In: Cardiology of the Horse. Marr C.M., Bowen I.M., editors. Elsevier; Philadelphia, PA: 2010; pp. 59–73.
    doi: 10.1016/B978-0-7020-2817-5.00011-0google scholar: lookup
  32. Gómez-Torres F., Ballesteros-Acuña L., Ruíz-Sauri A. Morphological variations of the conduction system in the atrioventricular zone and its clinical relationship in different species. Anat Sci Int 2021;96(2):212–220.
    doi: 10.1007/s12565-020-00575-7pubmed: 32997266google scholar: lookup
  33. Szymanski L.J., Ernst L.M. Cartilaginous metaplasia involving the atrioventricular node and bundle of His contributing to sudden early neonatal death. Pediatr Dev Pathol 2020;23(4):312–316.
    doi: 10.1177/1093526619892352pubmed: 31821773google scholar: lookup
  34. Gómez-Torres F., Ruíz-Sauri A. Morphometric analysis of the His bundle (atrioventricular fascicle) in humans and other animal species. Histological and immunohistochemical study. Vet Res Commun 2021;45(4):319–327.
    doi: 10.1007/s11259-021-09812-4pubmed: 34244914google scholar: lookup
  35. Durando M.M., Slack J., Birks E., Belcher C., Kohn C. Premature depolarisations in horses competing in United States Eventing Association and Fédération Equestre Internationale-sanctioned 3-day events. Equine Vet J 2023;56(1):59–68.
    doi: 10.1111/evj.13948pubmed: 37248851google scholar: lookup
  36. Patteson M.W., Cripps P.J. A survey of cardiac auscultatory findings in horses. Equine Vet J 1993;25(5):409–415.
    doi: 10.1111/j.2042-3306.1993.tb02982.xpubmed: 8223372google scholar: lookup
  37. Dun W., Boyden P.A. The Purkinje cell; 2008 style. J Mol Cell Cardiol 2008;45(5):617–624.
    doi: 10.1016/j.yjmcc.2008.08.001pmc: PMC4332524pubmed: 18778712google scholar: lookup
  38. Ohkawa S. Distribution of Purkinje cells in hearts of human and various animals. J Arrhythm 2008;24(4):177–179.
    doi: 10.1016/S1880-4276(08)80026-9google scholar: lookup
  39. Elbrønd V.S., Thomsen M.B., Isaksen J.L., Lunde E.D., Vincenti S., Wang T.. Intramural Purkinje fibers facilitate rapid ventricular activation in the equine heart. Acta Physiol 2023;237.
    doi: 10.1111/apha.13925pubmed: 36606541google scholar: lookup
  40. Gómez-Torres F.A., Estupiñán H.Y., Ruíz-Saurí A. Morphometric analysis of cardiac conduction fibers in horses and dogs, a comparative histological and immunohistochemical study with findings in human hearts. Res Vet Sci 2021;135:200–216.
    doi: 10.1016/j.rvsc.2021.02.013pubmed: 33618179google scholar: lookup
  41. Detweiler D.K. The mammalian electrocardiogram: comparative features. In: Comprehensive Electrocardiology. Macfarlane P.W., van Oosterom A., Pahlm O., Kligfield P., Janse M., Camm J., editors. Springer; London, UK: 2011; pp. 1909–1947.
    doi: 10.1007/978-1-84882-046-3google scholar: lookup
  42. Kotsialou Z., Makris N., Gall S. Fundamentals of the electrocardiogram and common cardiac arrhythmias. Anaesth Intensive Care 2024;25(3):219–222.
    doi: 10.1016/j.mpaic.2023.11.014google scholar: lookup
  43. Pedersen P.J., Kanters J.K., Buhl R., Klaerke D.A. Normal electrocardiographic QT interval in race-fit Standardbred horses at rest and its rate dependence during exercise. J Vet Cardiol 2013;15(1):23–31.
    doi: 10.1016/j.jvc.2012.08.002pubmed: 23434174google scholar: lookup
  44. Yu P.N.G., Bruce R.A., Lovejoy F.W., Pearson R. Observations on the change of ventricular systole (QT interval) during exercise. J Clin Invest 1950;29(3):279–289.
    doi: 10.1172/JCI102255pmc: PMC439750pubmed: 16695798google scholar: lookup
  45. Li M., Chadda K.R., Matthews G.D.K., Marr C.M., Huang C.L.-H., Jeevaratnam K. Cardiac electrophysiological adaptations in the equine athlete—restitution analysis of electrocardiographic features. PloS One 2018;13(3).
    doi: 10.1371/journal.pone.0194008pmc: PMC5844547pubmed: 29522557google scholar: lookup
  46. Fossa A.A., Wisialowski T., Crimin K., Wolfgang E., Couderc J.P., Hinterseer M.. Analyses of dynamic beat-to-beat QT–TQ interval (ECG restitution) changes in humans under normal sinus rhythm and prior to an event of Torsades de Pointes during QT prolongation caused by sotalol. Ann Noninvasive Electrocardiol 2007;12(4):338–348.
    doi: 10.1111/j.1542-474X.2007.00183.xpmc: PMC6932286pubmed: 17970959google scholar: lookup
  47. Taran L.M., Szilagyi N. The duration of the electrical systole (Q-T) in acute rheumatic carditis in children. Am Heart J 1947;33(1):14–26.
    pubmed: 20280672
  48. Linscheid N., Santos A., Poulsen P.C., Mills R.W., Calloe K., Leurs U.. Quantitative proteome comparison of human hearts with those of model organisms. PLoS Biol 2021;19.
    doi: 10.1371/journal.pbio.3001144pmc: PMC8084454pubmed: 33872299google scholar: lookup
  49. Edvardsson N., Hirsch I., Olsson S.B. Right ventricular monophasic action potentials in healthy young men. Pacing Clin Electrophysiol 1984;7(5):813–821.
    doi: 10.1111/j.1540-8159.1984.tb05622.xpubmed: 6207493google scholar: lookup
  50. De Clercq D., Broux B., Vera L., Decloedt A., Van Loon G. Measurement variability of right atrial and ventricular monophasic action potential and refractory period measurements in the standing non-sedated horse. BMC Vet Res 2018;14(1):101.
    doi: 10.1186/s12917-018-1399-ypmc: PMC5859751pubmed: 29558937google scholar: lookup
  51. Premont A., Saadeh K., Edling C., Lewis R., Marr C.M., Jeevaratnam K. Cardiac ion channel expression in the equine model - in-silico prediction utilising RNA sequencing data from mixed tissue samples. Physiol Rep 2022;10(14):1–14.
    doi: 10.14814/phy2.15273pmc: PMC9316921pubmed: 35880716google scholar: lookup
  52. Zingman L.V., Zhu Z., Sierra A., Stepniak E., Burnett C.M.-L., Maksymov G.. Exercise-induced expression of cardiac ATP-sensitive potassium channels promotes action potential shortening and energy conservation. J Mol Cell Cardiol 2011;51(1):72–81.
    doi: 10.1016/j.yjmcc.2011.03.010pmc: PMC3103621pubmed: 21439969google scholar: lookup
  53. Hiraoka M. Pathophysiological functions of ATP-sensitive K+ channels in myocardial ischemia. Jpn Heart J 1997;38(3):297–315.
    doi: 10.1536/ihj.38.297pubmed: 9290566google scholar: lookup
  54. Finley M.R., Li Y., Hua F., Lillich J., Mitchell K.E., Ganta S.. Expression and coassociation of ERG1, KCNQ1, and KCNE1 potassium channel proteins in horse heart. Am J Physiol Heart Circ Physiol 2002;283(1):H126–H138.
    doi: 10.1152/ajpheart.00622.2001pubmed: 12063283google scholar: lookup
  55. Pedersen P.J., Thomsen K.B., Olander E.R., Hauser F., Tejada M.A., Poulsen K.L.. Molecular cloning and functional expression of the equine K+ channel Kv11.1 (ether à go-go-related/KCNH2 gene) and the regulatory subunit KCNE2 from equine myocardium. PloS One 2015;10(9):1–19.
    doi: 10.1371/journal.pone.0138320pmc: PMC4574097pubmed: 26376488google scholar: lookup
  56. Pedersen P.J., Thomsen K.B., Flak J.B., Tejada M.A., Hauser F., Trachsel D.. Molecular cloning and functional expression of the K + channel K V 7.1 and the regulatory subunit KCNE1 from equine myocardium. Res Vet Sci 2017;113:79–86.
    doi: 10.1016/j.rvsc.2017.09.010pubmed: 28917093google scholar: lookup
  57. Gaborit N., Le Bouter S., Szuts V., Varro A., Escande D., Nattel S.. Regional and tissue specific transcript signatures of ion channel genes in the non-diseased human heart. J Physiol 2007;582(2):675–693.
    doi: 10.1113/jphysiol.2006.126714pmc: PMC2075332pubmed: 17478540google scholar: lookup
  58. Tanabe Y., Hatada K., Naito N., Aizawa Y., Chinushi M., Nawa H.. Over-expression of Kv1.5 in rat cardiomyocytes extremely shortens the duration of the action potential and causes rapid excitation. Biochem Biophys Res Commun 2006;345(3):1116–1121.
    doi: 10.1016/j.bbrc.2006.05.030pubmed: 16713996google scholar: lookup
  59. Maron B.J., Doerer J.J., Haas T.S., Tierney D.M., Mueller F.O. Sudden deaths in young competitive athletes: analysis of 1866 deaths in the United States, 1980–2006. Circ 2009;119(8):1085–1092.
    doi: 10.1161/CIRCULATIONAHA.108.804617pubmed: 19221222google scholar: lookup
  60. Dennis M., Elder A., Semsarian C., Orchard J., Brouwer I., Puranik R. A 10-year review of sudden death during sporting activities. Heart Rhythm 2018;15(10):1477–1483.
    doi: 10.1016/j.hrthm.2018.04.019pubmed: 29678777google scholar: lookup

Citations

This article has been cited 0 times.
Subscribe to our newsletter
Join 99,383 horse owners like you who receive our email updates on horse health and nutrition.