Effect of Marcha Exercise on Serum Electrolytes and Acid-Base Balance in Mangalarga Marchador Horses

The marcha competition is a functional evaluation, without similar in the world. In this competition, the animals perform marcha at average speed between 9 and 12 km/hr for 50 minutes, covering roughly 6 to 7 km with no rest. The aim of this study was to evaluate and compare the effect of batida gait competition on acid-base balance in Mangalarga Marchador horses during an official marcha competition. The study was conducted on 24 Mangalarga Marchador horses, 12 stallions, and 12 mares (aged 4-6 years and 399 ± 45 kg of body weight). Venous blood samples were collected before and after competition. Blood samples were analyzed for acid-base balance, as well as biochemical and electrolyte parameters. In stallions, a significant (P < .05) postexercise increase in pH, partial pressure of oxygen, bicarbonate concentration, base excess, and glucose was noted. Decrease (P < .05) in pCO2 (partial pressure of carbon dioxide), chloride and ionized calcium were observed after exercise only in stallions. No changes (P > .05) in hematocrit, hemoglobin, sodium, and potassium were observed after exercise in all animals. The changes in the acid-base balance and electrolyte profile of the Mangalarga Marchador stallions after marcha competition resulted in hypochloremic metabolic alkalosis. Marcha competition did not cause acid-base disturbance in mares. This study enables an evaluation and comparison of physical effort caused by the marcha exercise on acid-base balance in Mangalarga Marchador horses and provides further evidence of the existence of gender differences in sports horses.