Studies on the physiopathology of chronic obstructive pulmonary disease in the horse. V. Blood gas and acid-base values during exercise.

The research focuses on understanding how chronic obstructive pulmonary disease (COPD) affects the blood gas and acid-base levels in horses during exercise. The study suggests that horses suffering from COPD compensate for their respiratory dysfunction during exercise by extracting more oxygen from the blood than healthy horses. Additionally, it unveils a significant link between the production of lactic acid, standard bicarbonate changes, and the metabolic acidosis that occurs during exercise in horses, both healthy and with COPD.

Research Details

• The research was conducted on 5 healthy horses and 3 horses suffering from chronic obstructive pulmonary disease (COPD), monitoring various parameters during three stages of 1,200m exercise. The three stages were: the beginning (0-100m), the middle (500-600m) and the end (1100-1200m).
• The parameters included concentrations of haemoglobin, partial pressures of oxygen and carbon dioxide, oxygen content, pH (a measure of acidity or alkalinity), standard bicarbonate, and lactate and pyruvate (lactic and pyruvic acid) concentrations in arterial and mixed venous blood.
• The samples were collected simultaneously at the three stages of exercise using an automatic technique.

Findings and Conclusions

• The main finding demonstrated that COPD-affected horses compensated for their respiratory dysfunction during exercise by extracting more oxygen from their blood compared to healthy horses.
• The study identified significant changes in the mean values of PvO2 (partial pressure of oxygen), O2 content, and a-vO2 content (the difference between arterial and venous oxygen content) during exercise in COPD and healthy subjects.
• Furthermore, the research discovered a substantial correlation between the changes in standard bicarbonate and the changes in lactic acid concentration during exercise in both normal and COPD subjects. This result suggests that the production of lactic acid was the primary, but not the only, cause for the metabolic acidosis occurring during exercise. Metabolic acidosis refers to the situation when the body produces too much acid, leading to the acidity increase in the blood and other body tissues.

Importance of the Study

• This study provides valuable insights on how COPD affects the physiological variables under exercise conditions in horses, potentially aiding in the development of better treatment protocols.
• The relationship established between lactic acid concentration, standard bicarbonate changes and metabolic acidosis during exercise could be extrapolated to understand similar physiological responses in other mammals, including humans.