Effects of road transport on indices of stress in horses.

The research examines how road transport can contribute to stress in horses, focusing on its effects on pulmonary function and various other physiological parameters. The authors of the study found some changes in the horses’ physiological responses following transport but did not observe significant differences in pulmonary function before and after transport.

Research Methodology

• The researchers examined the effects of road transport on horses by studying four horses both before and after a 24-hour period of transportation. The experiment was conducted twice, once with a smooth ride setup (leaf-spring suspension and bias-ply tyres) and once with a rough ride setup (torsion-bar suspension and regular pressure radial tyres), to test different ride characteristics.
• Several measurements were taken before, during and after the transport including heart rates, rates of hay and water intake, faecal output, and serum cortisol concentration. The trailer’s temperature and levels of ammonia and carbon monoxide were also monitored.
• The horses were driven for 24 hours on a predominantly rural freeway route, with the trailer stopping every 3.75 hours for a 25-minute rest period.
• As a control, measurements were also taken for the horses over a 24-hour period while they were housed in their stalls.

Main Findings

• The study found no significant difference in the pulmonary aerosol washout rates of the horses before and after transport, indicating that transport did not significantly affect their pulmonary function.
• Heart rates during transport were unaffected by the type of suspension in the trailer or whether it was the horse’s first or second transport experiment. They were also not significantly different from the control measurements in the stall after the first 120 minutes of the experiment.
• However, increases were observed in red blood cell count, packed cell volume, haemoglobin, plasma protein and cortisol concentrations immediately after transport, which could indicate mild dehydration. Body weight was seen to decrease post transport.
• Water and hay intake rates were significantly lower during transport, contributing to the indication of mild dehydration.
• The temperatures within the trailer varied but generally stayed within the comfort range for large homeotherms. Levels of ammonia and carbon monoxide within the trailer during the transport period were within acceptable limits for human exposure. However, respirable particulates in the atmosphere were observed at levels above safe concentrations for humans, potentially indicating a poor quality of air within the trailer.

Concluding Remarks

• The study suggests that while there may be some physiological changes in horses during road transport, their pulmonary function and heart rate remain largely unchanged. However, the increased stress markers and decreased body weight may indicate a slight level of dehydration following road transport.
• The findings also indicate that even when temperature control and harmful gas levels are maintained within acceptable limits, the air quality in terms of particle content may need improvement during long periods of transport to ensure better conditions for the horses.