Authors: Dirikolu Levent, Waller Pamela, Malveaux Kesha, Lucas Cam H, Lomnicka Izabela, Pourciau Ashley, Bennadji Hayat, Liu Chin-Chi
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Total Carbon Dioxide Concentrations in Racehorses Regulatory testing for total serum carbon dioxide (TCO2) aims to detect alkalizing agents administered to enhance racehorse performance, but baseline values must account for biological variation before meaningful interpretation is possible. Researchers analysed pre- and post-race blood samples from Thoroughbreds and Quarter Horses across four Louisiana racetracks, using non-parametric statistical methods to evaluate factors influencing TCO2 concentrations. Pre-race samples showed significantly higher TCO2 levels (median 32.20 mmol/L) than post-race samples (26.70 mmol/L), with Thoroughbreds maintaining higher baseline concentrations (32.40 mmol/L) than Quarter Horses (31.30 mmol/L); breed, seasonal temperature, sampling timing, and track location all produced clinically meaningful differences in results. Temperature emerged as a particularly important variable affecting TCO2 across both breeds, though the interaction between seasonal variation and geographic location at different tracks could not be fully separated in the analysis. These findings have direct implications for veterinary screening protocols and disciplinary proceedings—establishing breed-specific, season-adjusted reference ranges rather than universal thresholds would improve the sensitivity and specificity of TCO2 testing as an anti-doping tool.
Read the full abstract on PubMed
Practical Takeaways
- •TCO2 testing baselines must account for breed differences, with Thoroughbreds showing higher baseline values than Quarter Horses
- •Sampling timing (pre- vs post-race), track location, and seasonal temperature are critical variables when interpreting TCO2 results for regulatory compliance
- •Single reference ranges for TCO2 may be inadequate; practitioners should consider whether location-specific and season-adjusted reference intervals improve detection of alkalizing agent abuse
Key Findings
- •Pre-race serum TCO2 concentration (32.20 mmol/L) was significantly higher than post-race samples (26.70 mmol/L, P < 0.0001)
- •Thoroughbreds had higher pre-race TCO2 (32.40 mmol/L) compared to Quarter Horses (31.30 mmol/L, P < 0.0001)
- •TCO2 concentrations varied significantly by racetrack location, ranging from 31.40 to 32.75 mmol/L (P < 0.0001)
- •Seasonal temperature variation significantly affected total serum TCO2 concentrations in both breeds (P < 0.0001)