Serum Cardiac Troponin I Concentration in Retired Racing Greyhounds

Abstract

Background: Cardiac troponin I (cTnI) is a polypeptide found specifically in cardiac muscle tissue that has been used as a diagnostic and prognostic indicator of cardiomyopathy. Increases in cTnI are associated with myocardial pathologic processes. However, high serum cTnI concentrations have been observed in normal Greyhounds.Hypothesis: We hypothesized that Greyhounds have cTnI concentrations higher than non-Greyhound dogs, and that a separate reference range should be established for Greyhounds.Animals: Blood samples were collected from the jugular vein from a group of 20 healthy Greyhound blood donors. Methods: Analysis of serum cTnI was performed with an immunoassay system with a detection level of 0.01 ng/mL, as described previously. The Greyhound values were compared with 2 groups of Boxers with and without arrhythmogenic right ventricular cardiomyopathy (ARVC), and to a group of non-Boxer control dogs from a previous study.Results: The mean cTnI concentration in Greyhounds was significantly higher (P o .0001) than that in non-Greyhound control dogs, although not significantly different from normal Boxers (P 5 .50), or Boxers with ARVC (P 5 .58). Greyhound serum cTnI concentrations were in the range found in Boxers with ARVC. The proposed reference range for cTnI in Greyhounds is 0.05-0.16 ng/mL.Conclusions and Clinical Importance: Greyhounds have a reference range for serum cTnI concentrations that differs from that of other previously published reference ranges for dogs of other breeds. Until a broader database and more precise reference range can be established, caution should be exercised in interpreting serum cTnI concentrations in Greyhounds with suspected cardiac disease.

The Influence of High-Intensity Moderate Duration Exercise on Cardiac Troponin I and C-Reactive Protein in Sled Dogs

“…The level of physical activity in endurance sled dogs is considered extreme. Normal activity as observed before racing in our study indicates that resting cTnI concentrations in fit sled dogs are similar to ranges established in normal healthy dogs 39 . Moderately strenuous activity patterns, such as performed in our study on 2 consecutive days, produced mild increases after racing, but values did not exceed the normal reference ranges (<0.11 ng/mL) set forth by our point of care monitoring system.…”

“…In addition, both of these dogs where cTnI concentration was above the reference range at rest returned to the reference range on day 1 and day 2 after racing. From our study 2 things are clear: sprint racing sled dogs do not have increased basal cTnI concentration as observed in resting Greyhounds, 39 and the physical activity undertaken on each day of a sprint race did not cause consistent dramatic increases outside of the upper limits of normal, as observed previously in endurance sled dogs.…”

Cardiac Troponins in Dogs and Cats

“…Greyhounds and Boxers might have inherently higher cTnI concentrations than other breeds . The minute amounts of troponin present in circulation in healthy individuals can likely be attributed to normal cardiomyocyte turnover .…”

Clinical pathology ofGreyhounds and other sighthounds

“…Cardiac troponin I (cTnI) is a polypeptide found specifically in cardiac muscle, and serum concentrations of cTnI have been used as a diagnostic and prognostic indicator of heart disease, including cardiac infarction in people and cardiomyopathy in dogs. Serum cTnI concentrations have been compared between RRGs, Boxers with and without arrhythmogenic right ventricular cardiomyopathy (ARVC), and non‐Boxer control dogs . Greyhounds had significantly higher serum cTnI concentrations compared with non‐Greyhound dogs, but significant differences in serum cTnI between Greyhounds and Boxers with and without ARVC were not found; interestingly, several Greyhounds had cTnI concentrations within or above the range of concentrations in the Boxers with ARVC.…”