These rugs cool by both conduction (contact) initially and then evaporation of water over a longer period! They initially cool by contact, depending on the temperature of the water they have been soaked in, but this effect only lasts for a few minutes. They then cool by evaporation for an extended period of time (1-4 hours or even longer in some cases), depending on the environmental conditions: temperature, humidity, airflow, and solar radiation (direct sunlight). They should only be used for comfort, for example, in hot weather or when travelling or after cooling with plenty of water after exercise. They must NEVER be relied upon for cooling HOT horses in any situation, nor can they be allowed to DRY OUT, as then they effectively become a blanket/sheet/rug and will heat the horse up.
Important Factors for Consideration in Choosing an Evaporative Cooling Rug
Cooling Area – The larger the area, the greater the contact with the horse and the higher the potential for cooling. But also dependent on other factors, including Water Holding Capacity, Under Rug Temperature, Evaporation Rate
Water Holding Capacity – The more water a rug holds, the greater the capacity for evaporation and the longer it should cool for. But also dependent on other factors, including Cooling Area, Under Rug Temperature, and Evaporation Rate.
Under Rug Temperature – The lower the under rug temperature (the temperature next to the horse’s surface) and the longer it is maintained, the better. However, this depends on other factors, including Cooling Area, Water Holding Capacity, Evaporation Rate, and Colour (Darker colours absorb more heat than light colours).
Evaporation Rate – The greater the evaporation rate, the cooler the under-rug temperature (next to the horse’s surface) should be. However, this also interacts with other factors, including Cooling Area, material type and thickness (insulation) and Water Holding Capacity and Colour (Darker colours absorb more heat from the sun than light colours).
Colour – The temperature under dark materials will be higher than under light materials due to “trapping” solar radiation. This becomes a factor as the rug surface starts to dry out. Once dry, light colours may still offer some cooling compared with dark colours, depending on the rug material and thickness.
The following LARGE or HORSE SIZE rugs were tested:
- Aerochill
- CoolAid
- Cotton sheet (Dark blue)
- Equi N Ice
- Equidaw
- Quick Chill (Equilibrium, Original)
- Quick Chill (Equilibrium, New)
- Equifreeze (Tack & Tailor)
METHODS
The cooling area of each rug was calculated by measuring the area of the cooling surface. Each rug was weighed using an industrial platform scale (Steinberg Systems, Floor Scale Warehouse Weigher 0-150kg, 10g resolution, calibrated with weights between 1 and 10kg), then soaked in water at 20°C for 5 minutes (or water and manufacturers water/alcohol coolant mixture as directed in the case of Equi-N-Ice). Rugs were hung for 5 minutes and then re-weighed. The difference between the dry weight and wet weight is the amount of water the rugs hold. Rugs were then hung over a line in full sunlight at 28-30°C and 55-45%RH with a moderate breeze. Under-rug temperature was recorded using Blue Maestro Tempo Discs linked to the Tempo Disc App, which was running on an iPhone 15 Pro Max.
RESULTS:
COOLING AREA
Water Holding Capacity
Rug Surface Temperature and Under Rug Temperature
After 15 minutes, the surface temperatures of all the rugs, measured by thermal imaging, were similar and ranged between 18.1 °C and 19.6°C.
After 1h the temperature under all rugs was around 20-23°C, except for the Equi-N-Ice with either water/alcohol (24.5°C) or water only (28.3°C). By two hours the Cotton Sheet and the Cool Aid had heated up as well. All other rugs continued to maintain a lower temperature than ambient. As more water evaporated the cooling capacity of the rugs was reduced as reflected in an increasing under-rug temperature. The Tack & Tailor rug had essentially dried by 3h but due to its light colour continued to provide some cooling. By 4h only the AeroChill, Equilibrium Quick Chill, Equilibrium New and Equidaw continued to provide cooling.
Evaporation Rate
Summary
The AeroChill, Equilibrium Quick Chill (New), and, to some extent, the Equidaw of London, all performed well, providing a reasonable amount of cooling through evaporation over 4 hours, in the conditions tested (i.e., warm-hot weather, low humidity, full sunlight, and moderate breeze). These are conditions which favour evaporation.
The CoolAid rug only provided benefit for the first hour and would need to be re-soaked again after at least 2 hours. The same goes for the cotton sheet. The dark cotton sheet would have made the horse warmer by hour three, if not sooner.
The Equifreeze (Tack & Tailor) performed well over the first two hours and would need resoaking at around 2.5 hours, but being light in colour, it did not heat up as much as a darker rug would.
Another consideration may be the weight of a wet rug; the Aerochill, the Quick Chill (Equilibrium, New) and Equidaw, when wet, weigh between 5 and 7kg, which may be challenging to place on a large horse. If you only need a short period of cooling, then the Equifreeze is definitely worth considering.
The Equi-N-Ice provided very little benefit with either water/alcohol as supplied or water alone, even accounting for the faster evaporation as the rug held so little fluid. On the plus side, being a white open mesh, once the liquid has evaporated, it doesn’t make the horses as hot as dry rugs or dark rugs of the other products tested would.
Dr David Marlin’s Recommendations:
Quick Chill, Equilibrium (New) at £159
AeroChill ~£160
Equifreeze, Tack & Tailor £150
Part of this work was made possible through external funding support. All testing and research were conducted independently by Animalweb, and the findings reflect our own results and conclusions. The funding in no way influenced the outcome or results of the research and testing.
