Cooling down your horse after exercise is critical to the animal's wellbeing. Neil Clarkson looks at crucial techniques to ensure everything runs smoothly.
Horses are particularly good at two things. They're great at digesting grass and can turn on an athletic performance that makes humans look like plodders.
But they can't do both at once.
When a horse cranks up a gear or two, its digestive system all but shuts down. That's because the blood that normally delivers oxygen and fuel to power the gut is diverted to the horse's big muscles to power locomotion. The same happens in people, but the size and athletic nature of horses means the process happens on a much more industrial scale.
That means cooling down properly is essential to a horse's health and wellbeing. Failing to do so properly can potentially mean damaged muscles, laminitis, and even colic.
Before examining the cooling process, it's important to understand the physiological processes going on inside an exercising horse.
As the horse's big muscles move into gear, they demand more fuel for energy, and the oxygen needed to burn it.
 Cooling a horse down properly in hot conditions is important. |
This is delivered by the blood. Blood vessels dilate to carry more blood and the animal's heart rate increases to push more blood around the body.
However, the blood vessels serving the digestive system contract, reducing flow to the gut and effectively shutting down digestion.
The heart also pumps more blood with each beat. The demand for oxygen increases markedly, and the horse begins to breath faster and harder. Its nostrils flare to improve airflow into and out of the lungs.
But the muscles have a problem. All this exercising is producing waste products, which need to be removed promptly. They comprise:
- Heat: It seems remarkable, but only a quarter of the energy produced by the horse will go into locomotion. The rest will be lost as heat.
- Carbon dioxide: This is a byproduct produced by the muscles burning fuel, which is carried away by the blood to the lungs, where it is exhaled.
- Assorted other waste byproducts, also carried away by the blood to be filtered out by the kidneys and later expelled in the urine.
So how does the horse cope with the heat? It's a major issue because the muscles are huge and doing a lot of work.
For a start, the horse will be able to dispose of much of the heat through the lungs. Blood which has given its all to the muscles is returned to the heart and pumps on to the lungs, where it disposes of its carbon dioxide, recharges with oxygen, and offloads some of that heat.
Suitably recharged, it returns to the heart where a second pair of chambers fire it back around the body.
For some animals, such as dogs and cats, this is enough to keep them cool. For horses and people, it doesn't cut the mustard.
The heat continues to build and the brain's hypothalamus, monitoring the situation, issues a crucial command. It orders the fine capillaries near the surface of the skin to dilate. This enables overheated blood to circulate close to the skin, where it can shed some of its heat.
Depending on the amount of exercise and the air temperature, this may be enough to keep the horse cool. But if the heat continues to build, the hypothalamus has another trick up its sleeve. It orders the sweat glands into action.
Sweat oozes into the horse's coat. As it evaporates off the skin, it takes heat with it.
This sweating costs your horse valuable electrolytes and thickens the blood. This thicker blood is harder to pump around the body, but is able to carry more oxygen to the muscles.
By now, your horse has rolled out its full arsenal in its bid to stay cool and keep working.
Its fitness, fluid loss and the ambient air temperature will all now play a part in determining just how much work your horse can handle.
When you stop exercising, the signs of this integrated cooling system will be clear for all to see. The horse will be breathing hard and its nostrils flared. It's pulse will be high and its skin soaked in sweat. You will see bigger blood vessels standing out underneath his or her skin.
The work may be done, but the horse still has a lot of work to do in cooling down those big muscle groups, and returning to the state of equilibrium.
The first thing you need to assess is how hot the horse really is. The amount of sweat is not a reliable indicator, as the rate of evaporation off the skin and coat can vary dramatically, depending upon the humidity and heat of the day.
A more reliable indicator is to monitor the heart and breathing rates.
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