Traditional and quantitative analysis of acid-base and electrolyte imbalances in horses competing in cross-country competitions at 2-star to 5-star level.

BACKGROUND

Early recognition and management of acid-base, fluid, and electrolyte disorders are crucial for the maintenance of health and performance in equine athletes.

OBJECTIVES

To analyze changes in acid-base and electrolyte status associated with exercise during cross-country competitions at different levels using traditional and quantitative approaches.

ANIMALS

Thirty-eight eventing horses.

METHODS

Prospective observational study. Jugular venous blood samples were collected before and after the cross-country test of 25 international eventing competitions ranging from 2-star (formerly 1-star) to 5-star (formerly 4-star) level. Blood gas analysis was performed to determine pH, pCO , Na , Cl , and K and calculate HCO , tCO base excess (BE ), anion gap (AG), strong ion difference calculated from Na , K , Cl , and lactate (SID ), strong ion difference calculated from Na , K , and Cl (SID ), strong ion gap (SIG), and total nonvolatile weak buffer concentration (A ). Postexercise acid-base imbalances, diagnosed on the basis of the traditional approach, and the simplified strong ion model were compared.

RESULTS

Significant decreases in pH, Cl , SID , pCO , HCO , tCO , and BE as well as increases in K , SID , AG, TP, and A were observed between pre- and postexercise samples. The changes in acid-base parameters were significantly affected by the competition level. Using the strong ion approach, a higher proportion of horses was diagnosed with postexercise metabolic acidosis.

CONCLUSIONS AND CLINICAL IMPORTANCE

Regarding the complex acid-base changes in horses competing at cross-country competitions, the quantitative approach provided a more detailed analysis of the different factors contributing to acid-base balance than did the traditional approach.