The effect of intravenous fluids administered prior to competition: A randomized clinical.

Overview

• This study investigated whether administering intravenous (IV) fluids to horses before a competition improves hydration status and reduces heart rate during or after a long-distance ride in extreme heat and terrain.
• The results showed minimal laboratory changes and no significant difference in heart rates, suggesting that pre-ride IV fluid therapy may not provide meaningful hydration benefits under these conditions.

Background and Objective

• It is common practice at major equestrian events to give horses intravenous fluids before competition, especially in challenging environmental conditions.
• Despite its widespread use, there is limited scientific evidence supporting the effectiveness of this practice in improving hydration or cardiovascular parameters.
• The researchers hypothesized that pre-ride IV fluid therapy would:
  • Lower the horses’ heart rate during or after exercise
  • Improve laboratory indicators of hydration

Methods

• Population: 14 client-owned horses entered in a 45 km endurance ride conducted in extreme heat and difficult terrain.
• Design: Randomized controlled trial with two groups:
  • IVF group (intravenous fluids administered the day before the ride)
  • NIV group (no intravenous fluids administered)
• Timing of data collection: Blood samples and physical exams were performed at six points:
  1. T0: At home (baseline)
  2. T1: Check-in day before the ride
  3. T2: 2-3 hours after catheterization and treatment
  4. T3: One hour before the ride
  5. T4: 32 km into the ride
  6. T5: At the end of the ride
• Variables measured:
  • Heart rate
  • Laboratory hydration parameters including bicarbonate, sodium, potassium, chloride, calcium, glucose, lactate, blood urea nitrogen (BUN), creatinine, packed cell volume (PCV), and total protein concentration
• Statistical analysis: Two-way ANOVA to compare treatment groups across time points.

Results

• Total protein concentration at T2 was slightly lower in the IVF group by 0.5 g/dL (95% CI: -1.0 to -0.01 g/dL) compared to the NIV group. This suggests a mild dilution effect immediately after fluid administration.
• BUN concentration at T4 (32 km into the ride) was 4 mg/dL lower in the IVF group (p = 0.02; 95% CI: -7.3 to -0.9 mg/dL), indicating a slight improvement in kidney function or hydration status during mid-ride.
• No statistically significant difference in heart rates was observed between groups (IVF 36 ± 5 bpm vs. NIV 39 ± 3 bpm; p = 0.23), indicating that IV fluids did not influence cardiovascular response to exercise.
• Other measured laboratory parameters did not show clinically meaningful differences between groups at any time point.

Conclusions

• Administering intravenous fluids to horses the day before a strenuous endurance ride in extreme heat produced mild laboratory marker changes but did not confer significant clinical hydration benefits.
• Specifically, the treatment did not reduce heart rate during or after the ride, an important indicator of cardiovascular strain and fitness.
• This suggests that routine pre-ride IV fluid therapy may not be necessary or beneficial for horses competing in similar conditions.
• The findings provide evidence to guide veterinarians and riders in making informed decisions about fluid therapy practices before competition.
• Future research with larger sample sizes may clarify if specific subgroups or conditions could benefit from pre-ride IV fluids.