Acid-base and electrolyte effects of shortening steeplechase in a three-day-event.

The researchers analyzed the impact of changing weather conditions and steeplechase length on the electrolyte and acid-base balance in Thoroughbred horses. The study showed that shortening the steeplechase distance in humid and hot conditions led to a consistent recovery in only one aspect, plasma lactate level, and other effects varied depending on the trotting distance and temperature conditions.

Research Methodology

• The researchers simulated a Speed and Endurance test using a high-speed treadmill, mimicking the conditions of a three-phase Thoroughbred horse race.
• Eight well-conditioned Thoroughbred horses participated in the experiment, which was executed in various weather and course length conditions.
• Each test consisted of specific phases; Phase A (trotting for 10 minutes), Phase B (galloping for 2-4 minutes in varying weather conditions), Phase C (trotting for 30 minutes), and Phase X (walking for 10 minutes).
• Simulated weather conditions included cooler at 20 degrees Celsius and 50-60% humidity and hot and humid at 26-28 degrees Celsius with 80-85% relative humidity.

Sampling and Analysis

• Researchers collected pulmonary artery blood samples resting periods, at the end of Phases A and B, at different intervals during Phase C, and five minutes into Phase X.
• Additional samples were collected for lactate (LA) and glucose (GLC) analysis 5 minutes into Phase C and at the end of Phase X.
• They analyzed these samples for multiple parameters such as packed cell volume (PCV), haemoglobin (HB), total plasma protein (TP), sodium (Na), potassium (K), chloride (Cl), anion gap (AG), plasma glucose (GLC) and lactate (LA), pH, PCO2, bicarbonate (HCO3), and base excess (BE).

Key Findings

• Shortening the steeplechase distance by 50% under hot and humid conditions resulted in a consistent return to control measurements only for plasma LA.
• Changes in parameters such as PCV, HB, TP, K and Cl had more to do with the longer galloping distance during the 4 min B trials than the temperature of the laboratory.
• Alternatively, changes in LA, GLC, pH, PCO2, and AG were more related to hot and humid laboratory conditions than they were to galloping distance.
• The results suggest that combining these variables with physical measures like core temperature, bodyweight loss, point of fatigue on Phase C, and recovery heart rates could serve as efficient monitors for future studies investigating modifications to Phase C.