STUDIES ON THE PHYSIOPATHOLOGY OF CHRONIC OBSTRUCTIVE PULMONARY-DISEASE IN THE HORSE .5. BLOOD-GAS AND ACID-BASE VALUES DURING EXERCISE

  • 1 January 1981
    • journal article
    • research article
    • Vol. 48  (4) , 239-249
Abstract
Hb concentration, the partial pressures of O2 and CO2, O2 content and the pH were determined in the arterial and mixed venous blood of 5 normal and 3 horses with chronic obstructive pulmonary disease (COPD) at 3 stages of an exercise distance of 1200 m. Arterial and mixed venous samples were collected simultaneously by an automatic technique during the walk, trot and gallop at 0-100, 500-600 and 1100-1200 m. Standard bicarbonate and lactic and pyruvic acid concentrations were also determined in arterial and mixed venous blood. Highly significant changes in the mean values of P.hivin.vO2 [mixed venous O2 partial pressure], O2 content and .DELTA. a[arterial]-.hivin.vO2 content occurred during exercise in COPD subjects, and significant changes in P.hivin.vO2 and .DELTA. a-.hivin.vO2 content occurred during exercise in normal subjects. COPD subjects compensated for respiratory dysfunction during exercise by extracting more O2 from the blood than did normal horses. There was a highly significant correlation between the changes in standard bicarbonate and the changes in lactic acid concentration during exercise in normal and COPD subjects. Lactic acid production was primarily, but not completely, responsible for the metabolic acidosis of exercise in horses.

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