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Too_Hot_To_Work

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					Too Hot To Work.

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805

Summary:
The horse is a great athlete, capable of strenuous exercise over
prolonged periods. But all that muscular activity generates heat. This
causes an increase in body temperature. Under normal circumstances the
horse is able to lose the excess heat and maintain its body temperature
within tightly controlled limits.

In response to the release of epinephrine, and the increase in skin
temperature, the horse starts to sweat. Evaporation of sweat is the most
important means of losi...


Keywords:
horse,heat stroke, heat stress, exhaustion, electrolytes


Article Body:
The horse is a great athlete, capable of strenuous exercise over
prolonged periods. But all that muscular activity generates heat. This
causes an increase in body temperature. Under normal circumstances the
horse is able to lose the excess heat and maintain its body temperature
within tightly controlled limits.

In response to the release of epinephrine, and the increase in skin
temperature, the horse starts to sweat. Evaporation of sweat is the most
important means of losing heat available to the horse. Sweat secreted
onto the skin draws heat from the horse as it evaporates. Evaporation
from the respiratory tract also plays a role in cooling.

Some heat is lost through convection. The body surface warms the
surrounding air, which conducts the heat away. Loss of heat by convection
is most effective when the temperature of the air surrounding the horse
is low. When the environmental temperature approaches that of the horse’s
body, heat loss by convection is greatly reduced. Air movement at the
body surface helps by removing the warmed air and replacing it with
cooler air.

But all that sweating has its drawbacks. Prolonged sweating can result in
significant loss of fluids. A horse can lose as much as 40 litres of
fluid during an endurance ride.

And it is not only the fluid loss that is important. Equine sweat
contains electrolytes (salts) such as sodium, potassium and chloride,
often in higher concentrations than in the blood.

So prolonged sweating can result in the loss of significant quantities of
electrolytes from the body. This can lead to colic, and muscle weakness
and can be potentially life threatening.
Evaporation increases in hot dry conditions. The horse may sweat so much
that he becomes dehydrated. But humid conditions reduce the heat loss
through evaporation. The horse may be unable to lose enough heat and
become dangerously overheated.

Horses working in hot conditions are at risk of developing heat stroke or
becoming exhausted. Heat stroke is more common in horses doing fast,
strenuous work and is the result of the horse being unable to lose enough
heat. Affected animals become distressed. The rectal temperature rises
above 40 degrees centigrade

Heat stroke is a problem that needs to be corrected very quickly.
Affected horses can collapse and die within minutes if not treated.

The horse must be cooled as quickly as possible to avoid permanent
damage. The best way to do this is to pour iced water all over the
horse’s body. Walking the horse for 30 seconds in between applying the
water helps. The movement stimulates the blood supply to the skin,
encouraging heat loss. The air movement over the body promotes heat loss
through evaporation.

As the horse cools down, offer half a bucket of water periodically. Oral
electrolyte solutions are better than plain water, providing the horse
will drink them. There is no advantage in offering cooled water to drink.
Studies show that horses usually drink more if the water is offered at
ambient temperature.

Exhaustion tends to be more a problem of horses taking part in endurance,
or other longer but lower speed, activities. The prolonged need for heat
loss leads to fluid and electrolyte disturbances.

Exhausted horses are depressed, and have no interest in food or water.
Again the rectal temperature is above 40 degrees. The skin is dehydrated.
In addition to being cooled, these horses need further treatment to
support the circulation and prevent shock. Horses may have lost over 30
litres of fluid which will need to be replaced. But because they have
also lost electrolytes they often show no interest in drinking despite
the fluid deficit. So it is usually necessary for fluids to be given into
the vein or by stomach tube.

If you are competing in hot conditions, what can you do to prevent
problems? Make sure that your horse is well hydrated before starting
work. Encourage him to drink. Sometimes horses dislike the flavor of the
water when they are away from home. Adding flavorings such as apple juice
to the water at home and then adding it to the water at the competition
may help.

Give the horse as many opportunities as possible to drink during breaks
in the exercise. Stand him in the shade whenever possible and take
advantage of any breeze to help keep him cool.

Most horses that are in light work, and receiving a balanced diet with
access to a salt lick, do not need electrolyte supplements. But horses
may benefit from them if they are taking part in more demanding sports,
such as endurance riding or eventing.

Giving electrolytes before, during and after strenuous work, helps
replace the losses and prevent dehydration. Electrolytes specifically
designed for horses are now available. Those that are produced for cattle
are not necessarily suitable. Your equine veterinarian will be able to
advise you about the most appropriate products.

				
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posted:3/1/2010
language:English
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