Physiological, behavioral, and serological responses of horses to shaded or unshaded pens in a hot, sunny environment.

The research paper explores the impact of providing shade to horses in hot and sunny climates. It discusses the physiological, behavioral, and serological responses of horses when kept in shaded versus unshaded pens. The experiment indicates that horses can benefit from shades as it reduces physiological and behavioral changes due to heat.

Methods Used

• The experiment was conducted on twelve healthy adult horses placed in either fully shaded (SH) or unshaded (SUN) pens during summer days in Davis, California.
• The horses were observed over a 5-day period with both groups having a chance to experience both conditions.
• Physiological parameters such as rectal temperature, respiration rate, skin temperature, and sweat scores were recorded hourly from 1230 to 1730 hours each day. Behavioral observations were also recorded during this time for parameters like proximity to water, foraging behaviour, locomotion, and insect avoidance behaviors.
• Daily blood samples were collected from the horses and cortisol, hematocrit, and the neutrophil-to-lymphocyte ratio were measured to monitor stress levels.
• Environmental conditions were recorded using automated and handheld sensors.

Key Findings

• The experiment found that the rectal and skin temperature along with the respiration rate were higher in horses kept under unshaded conditions (SUN), suggesting they were experiencing more heat stress.
• Moreover, horses in the unshaded pens exhibited more sweat (51.4%) compared to those in the shaded pens (1.1%).
• It was observed that horses in the sun spent more time standing near their water sources, indicating an increased need for cooling and hydration.
• The cortisol levels were also found to be higher in horses kept in the sun, indicating some level of heat-related stress, but they were still within the normal range for resting horses.
• No significant changes were observed in foraging, locomotion, or insect avoidance behavior between the two groups. There was also no significant difference in terms of hematocrit or the neutrophil-to-lymphocyte ratio between the two groups.

Conclusion

• The study concludes that provision of shade seems to reduce physiological and behavioral stress in horses, thus mitigating the effects of a hot and sunny environment.
• The findings of this study can be applied to develop best management practices for the care of domestic horses in hot, sunny environments.