FREE SHIPPING over $40
OVER 10000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Equine veterinary journal2020; 53(4); 656-669; doi: 10.1111/evj.13354

Exercise-associated rhythm disturbances in poorly performing Thoroughbreds: risk factors and association with racing performance.

Abstract: Exercise-associated cardiac rhythm disturbances are common, but there is a lack of evidence-based criteria on which to distinguish clinically relevant rhythm disturbances from those that are not. Objective: To describe and characterise rhythm disturbances during clinical exercise testing; to explore potential risk factors for these rhythm disturbances and to determine whether they influenced future racing. Methods: Retrospective cohort using a convenience sample. Methods: Medical records were reviewed from two clinical services to identify horses with poor performance and/or respiratory noise with both exercise endoscopy and electrocardiography results. Respiratory and ECG findings recorded by the attending clinicians were described, and for polymorphic ventricular rhythms (n = 12), a consensus team agreed the final rhythm characterisation. Several statistical models analysing risk factors were built and racing records were reviewed to compare horses with and without rhythm disturbance. Results: Of 245 racehorses, 87 (35.5%) had no ectopic/re-entrant rhythms, 110 (44.9%) had isolated premature depolarisations during sinus rhythm and 48 (19.6%) horses had complex tachydysrrythmias. Rhythm disturbances were detected during warm-up in 20 horses (8.2%); during gallop in 61 horses (24.9%) and during recovery in 124 horses (50.6%). Most complex rhythm events occurred during recovery, but there was one horse with a single couplet during gallop and another with a triplet during gallop. Fifteen horses (one with frequent isolated premature depolarisations and 14 complex rhythms) were considered by clinicians to be potentially contributing to poor performance. Treadmill exercise tests, the presence of exercise-associated upper respiratory tract obstructions and National Hunt racehorses were associated with rhythm disturbances. The proportion of horses racing again after diagnosis (82%) was similar in all groups and univariable analysis revealed no significant associations between subsequent racing and the presence of any ectopic/re-entrant rhythm, or the various sub-groups based on phase of exercise in which this was detected. Conclusions: Reliance on retrospective data collection from medical records with no control group. Exercise ECGs were collected using only 1 or 2 leads. Variables examined as risk factors could be considered to be inter-related and our sub-groups were small. Conclusions: This study confirms a high prevalence of cardiac rhythm disturbances, including complex ectopic/re-entrant rhythms, in poorly performing racehorses. Detection of rhythm disturbances may vary with exercise test conditions and exercise-associated upper respiratory tract obstructions increase the risk of rhythm disturbances.
© 2020 EVJ Ltd.
Get Full Text
Publication Date: 2020-10-29 PubMed ID: 32979227DOI: 10.1111/evj.13354Google 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

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 prevalence and potential risk factors of exercise-associated cardiac rhythm disturbances in poorly performing Thoroughbred racehorses and their effects on racing performance.

Objective and Methodology

  • The purpose of this research was to identify and characterize cardiac rhythm disturbances among Thoroughbred horses, understand potential risk factors, and determine how these might affect future performance in races.
  • The study was a retrospective cohort, using data collected from the medical records of two clinical services. The researchers focused on horses with poor performance and/or respiratory noise that had undergone both exercise endoscopy and electrocardiography.
  • The respiratory and ECG findings were analyzed and a consensus team agreed on the final rhythm characterization for polymorphic ventricular rhythms in 12 of these horses.
  • The study implemented several statistical models to study risk factors and reviewed the racing records of the horses to compare those with rhythm disturbances and those without.

Results

  • Out of 245 racehorses studied, 87 had no abnormal rhythms, 110 had premature depolarizations during normal rhythm, and 48 had complex tachyarrhythmias, or abnormal fast heart rhythms.
  • Rhythm disturbances were detected at different phases of exercise: 8.2% during warm-up, 24.9% during gallop, and 50.6% during recovery. Most complex rhythm events occurred during recovery.
  • 15 horses were considered by clinicians to have performance issues potentially attributable to rhythm disturbances.
  • Factors such as treadmill exercise tests, exercise-associated upper respiratory tract obstructions, and being a National Hunt racehorse were found to be associated with rhythm disturbances.
  • The proportion of horses racing again after diagnosis was similar across all groups, and the analysis revealed no significant associations between subsequent racing and the rhythm disturbances or the various sub-groups based on the phase of exercise in which they were detected.

Conclusion

  • The researchers acknowledge the limitations of the study, including reliance on retrospective data collection, collection of exercise ECGs using only one or two leads, interrelation of the examined risk factor variables, and small sub-groups.
  • The study confirms a high prevalence of cardiac rhythm disturbances, including complex ectopic or re-entrant rhythms, in poorly performing racehorses.
  • The detection of rhythm disturbances may vary with exercise test conditions, and exercise-associated upper respiratory tract obstructions increase the risk of rhythm disturbances.

Cite This Article

APA
Marr CM, Franklin S, Garrod G, Wylie C, Smith L, Dukes-McEwan J, Bright J, Allen K. (2020). Exercise-associated rhythm disturbances in poorly performing Thoroughbreds: risk factors and association with racing performance. Equine Vet J, 53(4), 656-669. https://doi.org/10.1111/evj.13354

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 53
Issue: 4
Pages: 656-669

Researcher Affiliations

Marr, Celia M
  • Rossdales Diagnostic Centre, Newmarket, UK.
Franklin, Samantha
  • Equine Sports Medicine Centre, Bristol Vet School, University of Bristol, Bristol, UK.
  • Equine Health and Performance Centre, University of Adelaide, South Australia, SA, Australia.
Garrod, Georgie
  • Rossdales Diagnostic Centre, Newmarket, UK.
Wylie, Claire
  • Rossdales Diagnostic Centre, Newmarket, UK.
Smith, Lewis
  • Rossdales Diagnostic Centre, Newmarket, UK.
Dukes-McEwan, Jo
  • Department of Small Animal Clinical Science (Cardiology Service), Institute of Veterinary Science, Leahurst Campus, University of Liverpool, Neston, Cheshire, UK.
Bright, Jan
  • Colorado State University Veterinary Teaching Hospital, Fort Collins, CO, USA.
Allen, Kate
  • Equine Sports Medicine Centre, Bristol Vet School, University of Bristol, Bristol, UK.

MeSH Terms

  • Animals
  • Arrhythmias, Cardiac / veterinary
  • Electrocardiography
  • Horse Diseases / diagnosis
  • Horse Diseases / epidemiology
  • Horse Diseases / etiology
  • Horses
  • Physical Conditioning, Animal
  • Retrospective Studies
  • Risk Factors

References

This article includes 35 references
  1. Reef VB, Bonagura J, Buhl R, McGurrin MK, Schwarzwald CC, van Loon G. Recommendations for management of equine athletes with cardiovascular abnormalities.. J Veterin Intern Med 2014;28:749-61.
  2. Martin BB Jr, Reef VB, Parente EJ, Sage AD. Causes of poor performance of horses during training, racing, or showing: 348 cases (1992-1996).. J Am Vet Med Assoc 2000;216:554-8.
  3. Jose-Cunilleras E, Young LE, Newton JR, Marlin DJ. Cardiac arrhythmias during and after treadmill exercise in poorly performing thoroughbred racehorses.. Equine Veterin J 2006;36:163-70.
  4. Buhl R, Petersen E, Lindholm M, Bak L, Nostell K. Cardiac arrhythmias in standardbreds during and after racing - possible association between heart size, valvular regurgitations and arrhythmias.. J Equine Vet Sci 2013;33:590-6.
  5. Physick-Sheard PW, McGurrin MK. Ventricular arrhythmias during race recovery in standardbred racehorses and associations with autonomic activity.. J Veterin Intern Med 2010;24:1158-66.
  6. Ryan N, Marr CM, McGladdery AJ. Survey of cardiac arrhythmias during submaximal and maximal exercise in thoroughbred racehorses.. Equine Vet J 2005;37:265-8.
  7. Slack J, Boston RC, Soma LR, Reef VB. Occurrence of cardiac arrhythmias in standardbred racehorses.. Equine Vet J 2015;47:398-404.
  8. Navas de Solis C, Green CM, Sides RH, Bayly W. Arrhythmias in thoroughbreds during and after treadmill and racetrack exercise.. J Equine Vet Sci 2016;42:19-24.
  9. Wijnberg ID, Franklin SH. The heart remains the core: cardiac causes of poor performance in horses compared to human athletes.. Comp Exerc Physiol 2017;13:149-74.
  10. Ohmura H, Hiraga A, Takahashi T, Kai M, Jones JH. Risk factors for atrial fibrillation during racing in slow-finishing horses.. J Am Vet Med Assoc 2003;223:84-8.
  11. von Elm E, Altman DG, Egger M, Pocock SJ, Gotzsche PC, Vandenbroucke JP. The strengthening the reporting of observational studies in epidemiology (STROBE) statement: guidelines for reporting observational studies.. Lancet 2007;370:1453-7.
  12. Barnett TP, Smith LC, Cheetham J, Barakzai SZ, Southwood L, Marr CM. A call for consensus on upper airway terminology.. Equine Vet J 2015;47:505-7.
  13. Prentice RL, Pyke R. Logistic disease incidence models and case-control studies.. Biometrika 1979;66:403-11.
  14. Hosmer DW, Lemeshow S. Applied logistic regression, 2nd edn.. 2000;91-202.
  15. Dohoo IR, Martin W, Stryhn H. Veterinary Epidemiologic Research, 2nd edn.. 2009;365-422.
  16. Perneger TV. What's wrong with Bonferroni adjustments.. BMJ 1998;316:1236-8.
  17. Savitz DA, Olshan AF. Multiple comparisons and related issues in the interpretation of epidemiologic data.. Am J Epidemiol 1995;142:904-8.
  18. Paterson DJ. Antiarrhythmic mechanisms during exercise.. J Appl Physiol 1996;80:1853-62.
  19. Beckerman J, Wu T, Jones S, Froelicher VF. Exercise test-induced arrhythmias.. Prog Cardiovasc Dis 2005;47:285-305.
  20. Allen KJ, Franklin SH. Assessment of the exercise tests used during overground endoscopy in UK thoroughbred racehorses and how these may affect the diagnosis of dynamic upper respiratory tract obstructions.. Equ Vet J 2010;38:587-91.
  21. Franklin SH, Allen KA. Laboratory exercie testing.. 2014:11-24.
  22. Rose RJ, Hodgson DR. Clinical exercise testing.. 1994; p. 245-57.
  23. Buhl R, Ersboll AK, Eriksen L, Koch J. Changes over time in echocardiographic measurements in young standardbred racehorses undergoing training and racing and association with racing performance.. J Am Vet Med Assoc 2005;226:1881-7.
  24. Buhl R, Ersboll AK. Echocardiographic evaluation of changes in left ventricular size and valvular regurgitation associated with physical training during and after maturity in standardbred trotters.. J Am Vet Med Assoc 2012;240:205-12.
  25. Lightfoot G, Jose-Cunilleras E, Rogers K, Newton JR, Young LE. An echocardiographic and auscultation study of right heart responses to training in young national hunt thoroughbred horses.. Equ Vet J 2006;36:153-8.
  26. Young LE. Cardiac responses to training in 2-year-old thoroughbreds: an echocardiographic study.. Equ Vet J 1999;30:195-8.
  27. Young LE, Rogers K, Wood JL. Left ventricular size and systolic function in thoroughbred racehorses and their relationships to race performance.. J Appl Physiol (1985) 2005;99:1278-85.
  28. Sharma S, Merghani A, Mont L. Exercise and the heart: the good, the bad, and the ugly.. Eur Heart J 2015;36:1445-53.
  29. Benito B, Gay-Jordi G, Serrano-Mollar A, Guasch E, Shi Y, Tardif JC. Cardiac arrhythmogenic remodeling in a rat model of long-term intensive exercise training.. Circulation 2011;123:13-22.
  30. Guasch E, Benito B, Qi X, Cifelli C, Naud P, Shi Y. Atrial fibrillation promotion by endurance exercise: demonstration and mechanistic exploration in an animal model.. J Am Coll Cardiol 2013;62:68-77.
  31. Elliott AD, Mahajan R, Linz D, Stokes M, Verdicchio CV, Middeldorp ME. Atrial remodeling and ectopic burden in recreational athletes: Implications for risk of atrial fibrillation.. Clin Cardiol 2018;41:843-8.
  32. Franklin SH, Allen KA. Assessment of dynamic upper respiratory tract function in the equine athlete.. Equine Vet Educ 2017;29:92-103.
  33. Maxson-Sage A, Parente EJ, Beech J, Lindborg S, May LL, Teleis DC. Effect of high-intensity exercise on arterial blood gas tensions and upper airway and cardiac function in clinically normal quarter horses and horses heterozygous and homozygous for hyperkalemic periodic paralysis.. Am J Vet Res 1998;59:615-8.
  34. May AM, Van Wagoner DR, Mehra R. OSA and cardiac arrhythmogenesis: mechanistic insights.. Chest 2017;151:225-41.
  35. Hohl M, Linz B, Bohm M, Linz D. Obstructive sleep apnea and atrial arrhythmogenesis.. Curr Cardiol Rev 2014;10:362-8.

Citations

This article has been cited 7 times.
  1. Kenchaiwong W, Sangpo P, Kusol A, Pontaema T, Lerdweeraphon W. The position of ground electrode affects electrocardiographic parameters in horses. Vet World 2022 Apr;15(4):1107-1112.
    doi: 10.14202/vetworld.2022.1107-1112pubmed: 35698497google scholar: lookup
  2. Nath L, Stent A, Elliott A, La Gerche A, Franklin S. Risk Factors for Exercise-Associated Sudden Cardiac Death in Thoroughbred Racehorses. Animals (Basel) 2022 May 18;12(10).
    doi: 10.3390/ani12101297pubmed: 35625143google scholar: lookup
  3. Ter Woort F, Dubois G, Tansley G, Didier M, Verdegaal L, Franklin S, Van Erck-Westergren E. Validation of an equine fitness tracker: ECG quality and arrhythmia detection. Equine Vet J 2022 Feb 9;55(2):336-43.
    doi: 10.1111/evj.13565pubmed: 35138653google scholar: lookup
  4. Alberti E, Stucchi L, Lo Feudo CM, Stancari G, Conturba B, Ferrucci F, Zucca E. Evaluation of Cardiac Arrhythmias before, during, and after Treadmill Exercise Testing in Poorly Performing Standardbred Racehorses. Animals (Basel) 2021 Aug 16;11(8).
    doi: 10.3390/ani11082413pubmed: 34438870google scholar: lookup
  5. Navas de Solis C, Ramseyer A, Stefanovski D, Haughan J, Solomon CJ, Kirsch K. Association of heart rate variability, exercise intensity and exercising arrhythmias with competition results in eventing horses. Equine Vet J 2025 Nov;57(6):1446-1456.
    doi: 10.1111/evj.14491pubmed: 40008417google scholar: lookup
  6. Navas de Solis C, Solomon C, Durando M, Stefanovski D. Electrocardiograms from different types of exercise in Eventing horses with and without cardiac signs. Equine Vet J 2025 Jul;57(4):991-1000.
    doi: 10.1111/evj.14449pubmed: 39632364google scholar: lookup
  7. Nath LC, Elliott A, La Gerche A, Weir J, Forbes G, Thomas G, Franklin S. Associations between postrace atrial fibrillation and measures of performance, racing history and airway disease in horses. J Vet Intern Med 2023 Nov-Dec;37(6):2573-2583.
    doi: 10.1111/jvim.16878pubmed: 37740606google scholar: lookup
Subscribe to our newsletter
Join 99,727 horse owners like you who receive our email updates on horse health and nutrition.