Cooling legs: how should it be done?
Kieran O’Brien MRCVS of EqWest Equine Veterinary Clinic, Tavistock, Devon advises on the most effective ways to cool a horse’s legs after the cross country.
One thing can be said with certainty: none of the runners competing in the last Olympics applied a strong-smelling clay paste, brown paper and bandages to their legs after the end of the race. Yet this curious, almost medieval practice is common in eventing. What are the arguments for these post-event applications?
Studies have shown that core temperatures in the flexor tendons of horses can increase to up to 45 degrees C (normal temperature 38 degrees C) after high speed galloping. Laboratory studies with cultures of cells obtained from horses have shown that tendon cells are remarkably resistant to this abnormally high temperature in comparison with skin cells (where this temperature causes rapid cell death).
However, it is considered that repeated bouts of temperature elevations in tendons may eventually contribute to tendon breakdown. Furthermore if tendon boots are worn they promote this heating by inhibiting the cooling effect of air passing over the leg as the horse gallops.
Horses competing in jumping events may bang their legs against fences, potentially causing bruising and inflammation. So there are therefore two good reasons for cooling horses’ legs after the cross country phase: firstly to cool the tendons, and secondly to limit inflammation generally in the lower limbs. But how is this cooling to be done?
Anyone who has visited the stables at Badminton on the evening of cross country day will recall the overpowering smell of the various oils and liniments applied to the horses. Clay-based leg-cooling products act as carriers for volatile substances (hence the strong smell). When applied to the legs these substances evaporate (taking the heat with them), thereby causing a cooling effect. Contrary to some claims, the clay is totally inert and has no therapeutic properties whatever. In fact the clay has an insulating effect, which counteracts the cooling action.
Other cooling applications (usually gels) are mostly alcohol based. Alcohol has a low boiling point and evaporates rapidly at low temperatures, thereby cooling the surface it is applied to.
If you really must use clay (and I believe as a coolant it is very overrated – try putting some on your arm) it follows therefore that applying bandages (with or without brown paper!) on top of it is completely illogical as evaporation cannot take place. If clay is to be used it should be, as is the case in most racing yards, left uncovered. As soon as it has dried it should be washed off with cold running water. Arguably the main benefit in using clay is the necessity to wash it off with a cold hosepipe!
Bandaging may be justified to limit swelling and inflammation in the lower limbs but is incompatible with effective cooling. Bandages are normally only loosely applied over the clay/paper mix and only serve to warm up what you are trying to cool down.
Experiments have shown that cold running water is more effective at cooling tendons than ice. Cold running water is rarely available at horse events, although if it is it should be used. If not available my recommendation is to apply boots designed to absorb water (cool boots). Dunk these into a bucket of iced water just as the horse is being prepared for the cross country, and apply them once it returns to the box. Check the temperature frequently and replace – you are unlikely to overcool your horse’s legs. If you must use a cooling application of some sort apply cooling gels rather than clay pastes, leave uncovered, and wash off and replenish frequently. Having cooled you can then bandage. And chuck the clay in the bin.
