Physical exercise on serum electrolytes and acid base balance in Mangalarga Marchador horses submitted to cavalcade of 4, 8 and 20km

Acid-base and electrolyte disorders have been described in horses associated during and after exercise. The aim of the present study was to evaluate the effect of cavalcade competition on the acid-base and hydroelectrolytic balance in Mangalarga Marchador horses. For this purpose, 15 geldings, 6.2 +/- 1.2 years old and clinically healthy, were distributed into three groups of five animals each. Horses were trained to take part in cavalcade competitions. Animals were submitted to cavalcade along 4km (G4), 8km (G8), and 20km (G20) at mean speeds of 15km h(-1), 12km h(-1), and 12km h(-1), respectively. From each horse, venous blood samples were collected before exercise (T0) and immediately after (T1) cavalcade. Bicarbonate ion (HCO3-), pH, partial pressure of carbon dioxide (pCO(2)), partial pressure of oxygen (pO(2)), base excess (BE), hematocrit (Hct), sodium (Na+), potassium (K+), chloride (Cl-) and lactate were determined. The variables pH, pO(2) and pCO(2) were corrected in function of rectal temperature of each animal. Blood samples were analyzed for acid-base balance, as well as biochemical and electrolyte parameters using an i-STAT analyzer. Significant (P<0.05) increase in Hct, Na+, pH, HCO3- and BE were observed after cavalcade in G20 group. Decrease (P<0.05) in K+ and Cl-were also observed in G20 animals after cavalcade (T1). Changes in the acidbase balance and hydroelectrolytic profile of the Mangalarga Marchador after cavalcade of 20km resulted in hypochloremic metabolic alkalosis. The 20km cavalcade induced significant hydroelectrolytic and acid-base imbalances in Mangalarga Marchador horses.