Recovery from transport and acclimatisation of competition horses in a hot humid environment.

This research investigates how fit horses adjust to a hot and humid environment after being transported, with the goal of providing safe procedures for transportation and acclimatisation. The study analyzed data from six horses flown from Europe to Atlanta where the climate was significantly more thermally stressful and found that these horses, with proper management, could adapt without significant risk of heat illness.

Study Design and Observations

• The research involved a field-based study were six horses, aged between 7 to 12 years, were flown from Europe to Atlanta, necessitating a change in environment from a temperate climate to a hot, humid one. The horses were then given a period of 16 days to acclimatise.
• The weather conditions during acclimatisation in the new environment were found to be more thermally challenging compared to the original European climate. This factor was calculated using the wet bulb globe temperature index with a mean index of 27.6 in Atlanta versus 22.0 in Europe, a statistically significant difference.
• Upon arrival and following the flight, the horses had lost an average of 4.1% of their bodyweight. It took approximately 7 days for the horses to regain this weight.

Effects on the Horses and their Recovery

• During acclimatisation, water intake by the horses increased significantly during the day compared to the night.
• While the horses experienced an increase in their respiratory rate during the acclimatisation period, some of their other health indicators such as the resting morning and evening rectal temperature, heart rate, and plasma volume remained stable.
• The daily average exercise duration for horses was around 72 minutes, and the majority of this exercise happened at heart rates below 120 beats per minute, demonstrating that the horses were able to manage exertion in this hotter, more humid environment.

Conclusions drawn from Study

• Their white blood cell count was significantly higher at the morning of the 4th and 10th day after arrival when compared to before they left Europe. By the 16th day of acclimatisation, the change in white blood cells became statistically insignificant.
• The study concludes that horses can handle, without significant risk of heat diseases or other heat-related disorders, changes to hot and humid environmental conditions, as long as they have enough time to recover, the acclimatisation process is undertaken gradually, and they receive appropriate monitoring during this period.