Ventilatory alterations in normal horses in response to changes in inspired oxygen and carbon dioxide

The influence of various concentrations of CO2 and O2 in the inspired gases on minute volume (V), tidal volume (VT), and respiratory rate (breaths per min; BPM) was examined in nonanesthetized, nonsedated normal horses. The VT and BPM increased linearly in response to increases in inspired CO2 concentration and curvilinearly in response to decreases in inspired Os concentration. The V increased curvilinearly in response to both increases in inspired CO2 concentration and decreases in inspired O2 concentration.