When considering boots for our horses, whether they are tendon boots, brushing boots, schooling boots or cross country boots, most horse owners are now aware that the ‘modern’ horse boot should be breathable, but do we really understand the importance of choosing a breathable boot for our horses?
Firstly we must consider the horse’s leg.
The horse’s leg is made of many bones, joints and muscles with a complex structure of tendons and ligaments that support the weight of the horse’s body.
Because of the workload often put upon them, tendons and ligaments are frequent sites of injury and disease.
What is heat in the leg?
As tendons and ligaments continually extend and contract to allow the horse to move, they create heat as a ‘by-product’. This is a natural process.
However by design, horses tendons operate near failure limits when exercising – there’s a fine balance!
Temperature and Tendon Damage
Work by Alan Wilson and Allen Goodship (1994) at the University of Bristol showed that the temperature inside the tendons of horses galloping without boots on could reach 45°C. This is only second highest to muscle temperatures. The tendon temperatures are very high not only because of heat production within the tendons, but because they have a relatively poor blood supply, which in any other tissue would help remove heat.
Are these Temperatures of Concern?
In 1997 the same group published the results of a scientific study in which they showed that isolated tendon cells in culture were sensitive to heating.
When the tendon cells were heated for 10 minutes at 45°C, around 10% died, but when they were heated to 48°C for 10 minutes then around 80% died.
These results were also confirmed by a more recent study of equine tendon cells in Japan (Hosaka et al. 2006). This study also showed that the higher the temperature, the more tendon cells that died and that inflammatory mediators were released after heating. Inflammatory mediators are chemicals and hormones within the body that cause inflammation (heat, swelling, pain) and tissue damage. If tendon core (central) temperatures can reach 45°C during a few minutes galloping without boots, it is almost certain that they will get even hotter when boots are being worn.
What happens when you use boots on your horses legs?
The fact that the lower leg gets hot during exercise and even hotter when boots are used presents another potential problem: sweating. When boots are removed the leg underneath is often wet from sweat. When skin is in contact with moisture for a long time it becomes hyper-hydrated; this is the effect you see if you stay in the bath for too long.
Wet skin cannot “breathe” normally, and it becomes more permeable allowing greater absorption of anything on the skin. Wet skin is also more susceptible to mechanical damage, with an increased risk of abrasions and grazing. Finally, wet skin is also more susceptible to bacterial or fungal attack and hence a potentially increased risk of conditions such as mud fever, caused by the bacterium Dermatophilus congolensis.
Considerations:
Many boots claim to be breathable, however some boots are more breathable than others.
