BLOOD-GAS TENSIONS AND ACID-BASE STATUS IN PONIES DURING TREADMILL EXERCISE

  • 1 January 1984
    • journal article
    • research article
    • Vol. 45  (1) , 15-19
Abstract
Blood-gas tensions and acid-base status were examined in 8 healthy grade ponies at rest (heart rate = 55 .+-. 3 beats/min) and during moderate (fast trot; heart rate = 155 .+-. 3 beats/min) and severe (gallop; heart rate = 218 .+-. 7 beats/min) exercise performed on a treadmill. Arterial O2 tension and hemoglobin-oxygen saturation of exercising ponies did not change from the resting values. Arterial O2 content increased markedly during exercise, as a consequence of increased Hb concentration. Total O2 content and the saturation of Hb with O2 in the mixed venous blood decreased at each intensity of exercise. Arterial CO2 tension decreased with moderate (16%) and severe (29%) exercise, indicating hyperventilation. In galloping ponies, during steady-state severe exercise marked metabolic acidosis developed, as indicated by a sharp increase in the arterial concentration of lactic acid (11.6 .+-. 1.3 mM during severe exercise vs. 0.6 .+-. 0.3 mM at rest). This increase in lactate was accompanied by a decrease in arterial pH and HCO3- concentration.