Horses are, like humans and all other mammals, warm blooded (including the so-called cold-blood breeds). This means that the body’s temperature is regulated internally and not by external influences (the sun).
A direct result of this is the minimal variation in temperature noted over the whole body. Some areas are slightly warmer because of the greater number of blood vessels running close to the surface of the skin; others are slightly cooler because of natural physiological reaction to the cold and the automatic attempt to maintain the core temperature.
The maximum variation in temperature within the body should be no more than about 2°C (on the surface this can be slightly more). This makes the following picture quite alarming:
We can see a very clear large decrease in temperature in the front right hoof and leg. Clearly the front of the legs is cooler than the rear (where the blood vessels run) and the muscular areas are much warmer; however, we see that the temperature of the hooves is very close to the temperature of the leg muscles. It is then horrific to note that from the knee downwards the leg with the shod hoof is considerably colder: as cold as the extreme surface of the other legs but then right through to the core.
This is as a result of the closing off of the blood vessels running through the underside of the navicular bone. Raising up the heels – as a result of standard shoeing practices – emulates the part of the pump system that along with the hoof mechanism insures efficient circulation through hooves and legs. The pump mechanism works by partially closing off the blood vessels and allowing a build-up of pressure; as soon as the vessels are fully opened, the pressure is released by pumping blood through. The problem is that there is no release from this partial emulation; the result is cold legs.
We can see in this next photograph just how concentrated the blood vessels in the hoof are; this means that, by definition, the hooves should be warm – as shown in the three unshod hooves in the thermograph above.
These pictures alone should be clear enough evidence that shoeing horses is not only unnecessary but also undesirable and even damaging. I would even go as far as to advocate that it is a form of cruelty since the horse is actually being abused.
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