Veterinarians and laminitis experts have suggested that the rapid chilling of the hooves in the very early stages of the disease has proven to be an effective way of halting the progression of this debilitating condition. This hypothesis has promoted a great deal of research on the topic and a new study has suggested that certain cooling techniques are more effective than others in helping slow down the inflammation of the soft laminae of the hoof which leads to laminitis.
Previous studies appeared to indicate that for optimal laminitis prevention, the hoof wall surface temperatures must be maintained at 5 to 10 degrees Celsius (41 to 50 degrees Fahrenheit) for 48 to 72 hours. Given the variety of methods available for achieving this level of cooling, a research team at the University of Queensland in Australia evaluated seven different methods to determine which were the most effective.
A. Dry Cooling These methods included four “dry” practices (meaning no water or ice came in contact with the hoof or leg) These were:
2. A commercial ice pack applied to the hoof wall only.
3. Two commercial cooling gel wraps applied to the hoof wall and extended over the fetlock and cannon bone.
4. A prototype boot that uses a refrigeration system to recirculate a coolant kept at a consistent 1 degree Celsius (33.8 degrees Fahrenheit) over the hoof and lower limb.
B. Wet Cooling These three cooling methods were “wet,” meaning water or ice came into direct contact with the hoof or leg. These were:
1. Ice wraps that covered only the upper leg and were then filled with ice
2. “Wader-style” ice boots, which encompassed both the hoof and lower limb and were then filled with ice.
3. A repurposed intravenous-fluid bag slipped over the hoof and pastern, filled with ice and then kept in place with adhesive tape.
To prevent anomalies in the research through variables across the methods, each method was trialed for the exact same length of time. Each type of treatment was applied to the forelegs of four horses for eight hours. Sensors were attached, allowing the researchers to track and record the temperatures of each test subject’s hoof walls. As a control, a sensor was also attached to the opposite forelimb and the ambient temperature was recorded hourly.
Overall, the results showed that the “wet,” cooling methods performed better than the dry method options. Cooling the limb as well as the foot was more effective than just chilling the hoof alone. For example, an ice pack to the hoof produced a median hoof wall surface temperature of 19.8 degrees Celsius (67 degrees Fahrenheit,) whereas an ice-filled bag covering the hoof and pastern lowered the median to 5.2 degrees Celsius (41 degrees Fahrenheit.)
It was concluded that the wet methods were more effective because they circumvented the body’s natural insulation. Where the hair on the limb is designed to keep the area warm by trapping a layer of static air close to the skin, when the limb is wet, heat conduction is increased as the insulating effect of the hair is reduced by the liquid. By immersing more than just the hoof, this horse’s blood is cooled before it begins circulating into the hoof.
There was one dry application that produced temperatures in the low range and this was the boot prototype. It is a variation of a commercially available system for limb cooling called Game Ready. It was designed with a gel interface to improve contact with the limb and a refrigeration unit and pump system with a very large cooling capacity. From a practical point of view, the boot was extremely useful. All that was required was to put the boots on, set the temperature and leave it. The horse would be able to walk around freely in the stable while tightly controlling cooling of all four feet. This is a stark contrast to conventional methods using water-and-ice methods which are labor intensive. To maintain the required temperature, they require replenishment at least every two hours, and application can be difficult for horses who are in pain. Additionally, intermittent cooling may cause more harm than good as there is some anecdotal evidence that on and off cooling might be worse than not cooling at all (with horses at risk of laminitis.)
*Image courtesy of Wikimedia Commons
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