Effect of racing on cardiac troponin I concentration and associations with cardiac rhythm disturbances in Standardbred racehorses.

Introduction/objectives: Accumulating evidence indicates intense exercise can be associated with myocardial damage. Investigating the impact of maximal effort on myocardium and exploring possible association of injury with rhythm disturbance requires a high-sensitivity cardiac troponin assay. The objectives of this study were: (1) to determine the effect of racing on serum cardiac troponin I (cTnI) in Standardbred horses using a high-sensitivity assay; (2) to determine the 99th percentile of cTnI in healthy horses and investigate the effect of demographic variables on cTnI prevailing pre-race in Standardbred horses using a validated high-sensitivity assay and a contemporary assay, and; (3) to explore associations between exercise-associated arrhythmia and cTnI concentration.

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

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.

Analytical validation of cardiac troponin I assays in horses.

Human cardiac troponin I (cTnI) assays have been used in equine medicine, often without prior analytical validation for equine use. In the absence of appropriate validation, the clinical significance of assay results is uncertain and can lead to misdiagnosis. We followed the American Society for Veterinary Clinical Pathology guidelines and investigated linearity, precision, limit of quantification (LoQ), and comparative recovery for 6 commercial cTnI assays developed for use in human medicine.

Troponin assays in the assessment of the equine myocardium.

In 2000, troponin assays were adopted as the test of choice for detection of myocardial injury in man. This decision was made after extensive testing and followed a 60 year search for a biomarker of myocardial damage with sufficient analytical sensitivity and specificity. This has led to proliferation of assays for use in human medicine, each requiring extensive testing and validation before it could be made available on the open market for human use.

Restriction fragment length polymorphism of porcine reproductive and respiratory syndrome viruses recovered from Ontario farms, 1998-2000.

From January 1998 to July 2000, 2,456 clinical samples, including lung, tonsil, lymph node, and serum, from 760 cases submitted to the Animal Health Laboratory, Ontario, Canada, were tested for porcine reproductive and respiratory syndrome viruses (PRRSV) using reverse transcriptase polymerase chain reaction (RT-PCR) and RT-PCR product restriction fragment length polymorphism (RFLP) analysis. A total of 516 samples from 284 cases were RT-PCR positive for the PRRSV open reading frame (ORF) 7 sequence. The RT-PCR RFLP typing assay was performed using 2 different sets of primers, amplifying 716 or 933 base pairs of ORF 4, 5, and 6 of PRRSV.