A study from Japan Racing Association’s Equine Research Institute found that a continuous shower of tap water was the most effective method.
Five Thoroughbreds were included in the study, which was carried out under hot and humid conditions (maintained at 31.8 °C +/- 0.1°C with heaters and mist sprays)
The horses were exercised on a treadmill until the temperature measured in their pulmonary artery reached 42°C. They were then cooled down following one of five protocols and their pulmonary artery and rectal temperatures and blood lactate levels were monitored.
Cooling protocols comprised:
- walking, with no additional cooling (control);
- walking, with fans producing an air current of 3.0 m/s
- walking, with the intermittent application of cold water (10°C) with scraping
- walking, with the intermittent application of cold water (10°C) without scraping
- stationary, with the continuous tap water (26°C) application via shower hoses
Researchers repeated the experiment weekly until all horses had experienced each cooling method.
They found that showering with tap water was significantly more effective than any other cooling method.
A full report of the work is published in the Journal of Equine Veterinary Science. The authors conclude: “The essential feature is not the water temperature or the use of scraping but that the horse is kept covered in water cooler than its body temperature over an extended period.”
For more details, see:
A Comparison of Five Cooling Methods in Hot and Humid Environments in Thoroughbred Horses
Yuji Takahashi 1, Hajime Ohmura 2, Kazutaka Mukai 1, Tomoki Shiose 3, Toshiyuki Takahashi
J Equine Vet Sci (2020) 91:103130.