Comparison of analyses of respiratory gases made with the K4b2 portable and Quark laboratory analysers in horses

Measurements of minute ventilation (V E ) and expired oxygen and carbon dioxide fractions (FeO 2 and FeCO 2 ) were measured at rest and during exercise in seven warmblood horses performing two consecutive standardised incremental treadmill exercise tests at submaximal speed, using the portable K4b 2 telemetric unit and the laboratory Quark metabolic cart in random order. Oxygen consumption (VO 2 ) and carbon dioxide production (VCO 2 ) were estimated using the Haldane equation. There were no significant differences between the measurements made with the two devices. However, V E was overestimated when the horses were cantering at 10 m/s in comparison with values available in the literature.