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Home / Equine Research Bank / J Vet Intern Med / Ventricular arrhythmias during race recovery in Standardbred...
Journal of veterinary internal medicine2010; 24(5); 1158-1166; doi: 10.1111/j.1939-1676.2010.0553.x

Ventricular arrhythmias during race recovery in Standardbred Racehorses and associations with autonomic activity.

Abstract: A lack of information on normal heart rhythm at maximal effort hampers investigation of poor performance and sudden death in Standardbred racing. Objective: To characterize rhythm variations during scheduled racing in clinically normal Standardbred horses. Methods: Two hundred and eighty-eight Standardbred horses competing in 40 scheduled races at a Southern Ontario racetrack. Methods: Observational study, convenience sampling: Heart rhythm was monitored by ECG from harnessing to postrace recovery and assessed visually and by examining heart rate intervals. Rhythm variations were used as response variables in multivariate analysis of race records detailing signalment, race, and race outcome. Results: Monitoring involved 345 individual horse or race events. Occasional, isolated premature cycles, only, occurred during the race. Postrace, sudden cardiac slowing (punctuated deceleration [PD]) appeared in 42 events (12.2%). Only premature ventricular complexes were exhibited in 40 events postrace (11.6%), whereas 55 (15.9%) exhibited complex ventricular arrhythmias (CVA) including torsades-like polymorphic ventricular tachycardia, 34.5% of these being closely associated with PD (odds ratio = 8). Predispositions to CVA were found for horses parked at the 1/2 mile (odds ratio = 3), and trotters breaking in the stretch (odds ratio = 38). Horses spontaneously reverted to sinus rhythm and no sudden death events were encountered. Conclusions: Arrhythmias occur frequently in racing Standardbreds during cardiac deceleration, often associated with sudden, rapid increases in vagal tone. Circumstances imposing unusual demand and racing at the trot appear to predispose. Findings provide insight into possible mechanisms of sudden death.
Copyright © 2010 by the American College of Veterinary Internal Medicine.
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Publication Date: 2010-06-24 PubMed ID: 20584140DOI: 10.1111/j.1939-1676.2010.0553.xGoogle Scholar: Lookup
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  • Journal Article
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  • Non-U.S. Gov't

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 study investigates the variations in heart rhythm during racing and post-racing recovery in clinically normal Standardbred racehorses. The study discovered that arrhythmias frequently occur during cardiac deceleration, often associated with sudden, rapid increases in vagal tone. The findings also provide possible mechanisms for sudden death.

Objective of the Study

  • The primary goal of this study is to understand the variations in heart rhythm during racing and post-race recovery in Standardbred horses. This research aims to fill the knowledge gap regarding normal heart rhythm during maximum exertion to aid in investigating poor performance and sudden death occurrences in Standardbred racing.

Methodology of the Research

  • The study involves the evaluation of 288 Standardbred horses participating in 40 scheduled races at a Southern Ontario racetrack. Utilizing convenience sampling as part of an observational study, the heart rhythm of each horse was monitored using an ECG from harnessing to postrace recovery.
  • The researchers visually assessed the heart rhythm and also examined heart rate intervals. The rhythm variations noted were subsequently used as response variables in a multivariate analysis of race records detailing the horses’ details, race conditions, and race outcomes.

Results of the Study

  • The study involved monitoring 345 individual horse or race events. During the races, only occasional, isolated premature cycles were noticed.
  • Post-race, sudden cardiac slowing (punctuated deceleration [PD]) appeared in 42 events (12.2%), and only premature ventricular complexes were exhibited in 40 events post-race (11.6%).
  • Furthermore, 15.9% (55 events) showed complex ventricular arrhythmias, including torsades-like polymorphic ventricular tachycardia, with 34.5% of these closely associated with PD. Having an odds ratio = 8 indicated a strong relation between a horse experiencing PD and displaying arrhythmias post-race.
  • Particular predispositions to CVA were found for horses parked at the 1/2 mile (odds ratio = 3), and trotters breaking in the stretch (odds ratio = 38). This indicates that circumstances imposing unusual demand and races at the trot seem to predispose horses to arrhythmias.
  • Interestingly, all the horses spontaneously reverted to a normal sinus rhythm post-race, and no sudden death events were noted during the study period.

Conclusion Of The Study

  • The research concludes that during the racing and recovery periods, Standardbred horses frequently encounter arrhythmias, often associated with sudden, rapid increases in vagal tone. The study also identifies circumstances that make horses more predisposed to such heart conditions, providing valuable insights into potentially preventing such fatal outcomes in the future.

Cite This Article

APA
Physick-Sheard PW, McGurrin MK. (2010). Ventricular arrhythmias during race recovery in Standardbred Racehorses and associations with autonomic activity. J Vet Intern Med, 24(5), 1158-1166. https://doi.org/10.1111/j.1939-1676.2010.0553.x

Publication

Journal of veterinary internal medicine
ISSN: 0891-6640
NlmUniqueID: 8708660
Country: United States
Language: English
Volume: 24
Issue: 5
Pages: 1158-1166

Researcher Affiliations

Physick-Sheard, P W
  • Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada. pphysick@uoguelph.ca
McGurrin, M K J

    MeSH Terms

    • Animals
    • Arrhythmias, Cardiac / etiology
    • Arrhythmias, Cardiac / veterinary
    • Autonomic Nervous System / physiology
    • Female
    • Horse Diseases / pathology
    • Horses
    • Male
    • Physical Conditioning, Animal / physiology
    • Sports

    Citations

    This article has been cited 16 times.
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