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Equine Vet J. 2019 Jan;51(1):97-101. doi: 10.1111/evj.12967. Epub 2018 Jun 28.

Post-exercise cardiac troponin I release and clearance in normal Standardbred racehorses.

Author information

1
Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
2
Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada.
3
Animal Health Laboratory, Laboratory Services Division, University of Guelph, Guelph, Ontario, Canada.
4
Centre for Cardiovascular Research, Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.

Abstract

BACKGROUND:

There are currently no studies detailing cardiac troponin I (cTnI) release in normal horses post-exercise using an analytically validated assay. These data are essential for selecting appropriate sampling times in equine athletes with suspected myocardial injury.

OBJECTIVE:

To plot the magnitude and time course of cTnI release after maximal effort, using validated cTnI assays.

STUDY DESIGN:

Descriptive longitudinal study.

METHODS:

Five clinically normal Standardbred racehorses in race training were included in the study. Horses were exercised in harness at near-race intensity. Blood samples were taken immediately pre- and post-exercise and then hourly for 24 h. Samples were analysed using the validated high-sensitivity cTnI assay and a contemporary sensitivity cTnI assay.

RESULTS:

Mean resting cTnI was 1.33 ± 0.6 s.d. ng/L (range, 0.82-2.33 ng/L) using assay A. All horses were below the detection limit at rest using assay B. Peak elevation occurred 2-6 h post-exercise with both assays (mean, 4.6 ± 1.7 and 4.0 ± 2 h, respectively). Mean peak increase in cTnI was 11.96 ± 9.41 ng/L (range, 1.72-23.76 ng/L) using assay A. Peak concentrations were detectable in three of the horses using assay B and were between 0.039 and 0.051 μg/L (mean: 0.043 ± 0.006 μg/L). All horses returned to baseline within 24 h.

MAIN LIMITATIONS:

A small (n = 5) convenience sample was used as random sampling was not logistically possible.

CONCLUSIONS:

All horses experienced an increase in cTnI post-exercise, with peak occurring 2-6 h post-exercise. Cardiac troponin I elevation was detected earlier using the high-sensitivity assay, which may convey a diagnostic advantage. Targeted studies are needed to determine the significance of these increases.

KEYWORDS:

biomarkers; cardiac troponin I; exercise physiology; horse; release curve

PMID:
29806966
DOI:
10.1111/evj.12486_62
[Indexed for MEDLINE]

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