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Equine veterinary journal1986; 18(1); 37-42; doi: 10.1111/j.2042-3306.1986.tb03533.x

Paroxysmal atrial fibrillation in racehorses.

Abstract: The paper describes five cases of atrial fibrillation detected after racing. In four of them, the arrhythmia disappeared spontaneously within 24 h and they were regarded as paroxysmal in type. In the fifth case, which won its race, the arrhythmia persisted for at least 45 h after racing. It was therefore regarded as an example of persistent atrial fibrillation. It was then treated with quinidine sulphate which restored sinus rhythm. It would seem that paroxysmal atrial fibrillation may be a cause of sudden decrease in racing performance.
Publication Date: 1986-01-01 PubMed ID: 3948829DOI: 10.1111/j.2042-3306.1986.tb03533.xGoogle Scholar: Lookup
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Summary

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The research article examines five instances of atrial fibrillation in racehorses, identifying paroxysmal atrial fibrillation as a potential reason behind unexpected drops in racing performance.

Article Overview

The study focuses on five racehorses that suffered atrial fibrillation following a race. For four of these horses, the arrhythmia faded naturally within a day, categorizing it as paroxysmal atrial fibrillation. One horse, however, experienced the condition for at least 45 hours post-race, marking it as persistent atrial fibrillation. Quinidine sulphate was used to successfully treat this condition and restore regular heart rhythm.

Details of Cases

  • The research involves five cases of racehorses experiencing atrial fibrillation, a heart condition that interferes with the normal rhythm of the heart, after participating in a race.
  • Of the five, four horses’ heart rhythm irregularity spontaneously resolved itself within 24 hours, categorizing these cases as paroxysmal atrial fibrillation, a type of atrial fibrillation that begins and ends spontaneously.
  • The fifth horse exhibited signs of persistent atrial fibrillation, where the irregular heart rhythm lasted for over 45 hours post-race.

Treatment of Persistent Atrial Fibrillation

  • Given the persistence of the irregular heart rhythm, the fifth horse was treated with a medication known as quinidine sulphate.
  • Following the administration of quinidine sulphate, the horse’s heart rhythm successfully returned to its normal sinus rhythm, thereby demonstrating the efficacy of this treatment strategy.

Implications for Racehorse Performance

  • The study highlights paroxysmal atrial fibrillation as a potential explanation for a sudden decrease in racehorse performance, implying that this condition could impact the speed and endurance of the animals during a race.
  • Consequently, this research could help inform future studies as well as diagnoses and treatment protocols for racehorses exhibiting a sudden decline in performance.

Cite This Article

APA
Holmes JR, Henigan M, Williams RB, Witherington DH. (1986). Paroxysmal atrial fibrillation in racehorses. Equine Vet J, 18(1), 37-42. https://doi.org/10.1111/j.2042-3306.1986.tb03533.x

Publication

ISSN: 0425-1644
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 18
Issue: 1
Pages: 37-42

Researcher Affiliations

Holmes, J R
    Henigan, M
      Williams, R B
        Witherington, D H

          MeSH Terms

          • Animals
          • Atrial Fibrillation / etiology
          • Atrial Fibrillation / physiopathology
          • Atrial Fibrillation / veterinary
          • Electrocardiography
          • Female
          • Horse Diseases / etiology
          • Horse Diseases / physiopathology
          • Horses
          • Male

          Citations

          This article has been cited 6 times.
          1. Kuroda T, Minamijima Y, Kinman CK, Takahashi Y, Ebisuda Y, Inoue K, Ishikawa H, Mita H, Tamura N, Nukada T, Toutain PL, Ohta M. Rational quinidine dosage regimen for atrial fibrillation in Thoroughbred racehorses based on population pharmacokinetics. Front Vet Sci 2024;11:1454342.
            doi: 10.3389/fvets.2024.1454342pubmed: 39439824google scholar: lookup
          2. Kjeldsen ST, Nissen SD, Christensen NC, Haugaard SL, Schneider MJ, Vinther Z, Sattler SM, Carstensen H, Jøns C, Hopster-Iversen C, Buhl R. Validation and clinical application of implantable loop recorders for diagnosis of atrial fibrillation in horses. Equine Vet J 2025 Mar;57(2):449-458.
            doi: 10.1111/evj.14112pubmed: 39031582google scholar: lookup
          3. 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
          4. Kjeldsen ST, Nissen SD, Buhl R, Hopster-Iversen C. Paroxysmal Atrial Fibrillation in Horses: Pathophysiology, Diagnostics and Clinical Aspects. Animals (Basel) 2022 Mar 10;12(6).
            doi: 10.3390/ani12060698pubmed: 35327097google scholar: lookup
          5. Nath LC, Elliott AD, Weir J, Curl P, Rosanowski SM, Franklin S. Incidence, recurrence, and outcome of postrace atrial fibrillation in Thoroughbred horses. J Vet Intern Med 2021 Mar;35(2):1111-1120.
            doi: 10.1111/jvim.16063pubmed: 33604980google scholar: lookup
          6. Buhl R, Nissen SD, Winther MLK, Poulsen SK, Hopster-Iversen C, Jespersen T, Sanders P, Carstensen H, Hesselkilde EM. Implantable loop recorders can detect paroxysmal atrial fibrillation in Standardbred racehorses with intermittent poor performance. Equine Vet J 2021 Sep;53(5):955-963.
            doi: 10.1111/evj.13372pubmed: 33113157google scholar: lookup