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A working horse can lose more than six gallons of sweat in one hour.
Electrolytes:
Who Needs 'Em?
By
Edgar A. Ott, Ph.D
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The
term "Electrolytes" brings a variety of responses from horse
owners. What are they? What do they do for my horse? How do I provide
them? How much does my horse need? Let's examine these questions and
try to reach an understanding of the importance of these nutrients.
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Electro
- What?
Electrolytes are the mineral elements that, when dissolved in water,
become ions, which are charged particles that conduct an electric
current. Electrolytes are used within the body to control pH and osmotic
pressure between the cells and the interstitial fluids. Electrolytes
also play an important role in muscle and nerve function. A deficiency
of electrolytes can lead to poor performance and dehydration.
Water Wars
The horse's body is compromised of about 65 percent water. Some of
that water is within the cells and some is outside the cells (interstitial).
The average 1,100-lb. horse would have approximately 85 gallons of
water; about 26 gallons are in the extracellular compartments and
10 gallons are in the plasma. The balance between the cell water and
the interstitial water is controlled by the concentrations of electrolytes
in each area. Potassium is the cation in the cell and sodium is the
primary cation in the interstitial fluid. If the sodium in the interstitial
fluid is reduced, the potassium in the cells must also be reduced
or the cells will fill with water and burst. This can lead to edema,
and in extreme cases, even death.
Chloride is the primary anion in the body. Calcium and magnesium are
also electrolytes but are less important than the other three because
their concentrations in the fluids are lower. There is a direct relationship
between electrolyte concentration in the interstitial fluid and the
water content of the body. Thus, as electrolyte levels in the body
decrease, the animal dehydrates. And the reverse also occurs. As the
body water decreases, the body electrolytes are excreted.
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It is important to always offer water after administering
electrolytes to ensure that the horse can properly balance its water/electrolyte
concentration. |
Lost
in the Sweat
One of the primary factors influencing body water and electrolyte
loss is perspiration. Perspiration losses are influenced by environmental
temperature, relative humidity and the amount of heat the animal needs
to lose. If the environmental temperature and humidity are high, the
increased heat load on the animal will require that the animal perspire
to maintain the desired body temperature. Heat production in the animal
is directly influenced by the activity of the animal. As the animal
exercises, he produces heat and must perspire to dissipate that heat.
There is a linear relationship between intensity of work and perspiration
loss. Perspiration loss also results in electrolyte loss. Although
the data suggests that perspiration electrolyte concentrations could
vary between individuals and perhaps with time, the data of Meyer
(1987) will illustrate the quantity of minerals that are lost as perspiration
increases (Table 1). Five liters (1.3 gallons) of perspiration would
likely match horses doing light work for an hour in the Southeast.
Fluid loss can approach 15 liters (4 gallons) per hour when it is
very hot. Twenty-five liters (6.6 gallons) would be likely only for
horses doing intense work such as race training or endurance type
activities.
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How
do I provide electrolytes for my horse?
Commercial feeds contain added salt, an excellent source of sodium
(Na+) and chloride (Cl -). Most commercial concentrates contain 0.75
to 1.0 percent salt. If the horse is being fed 1 lb. of concentrate
per 100 lbs. of bodyweight daily, the concentrate minerals will provide
most if not all of the electrolytes the horse needs. For an 1100-lb
horse consuming 11 lb. of concentrate, the animal would be getting
37.5 to 50 g. of salt, an amount adequate for a horse doing light
work. However, if the horse is perspiring heavily, the animal will
need more sodium and chloride. This can be provided by offering a
free-choice salt in the stall or pasture. Working horses may need
more salt than they can consume from these two sources. Electrolyte
supplementation is therefore needed. Salt or mixed electrolyte products
can be top-dressed on the feed, added to water used to rehydrate the
horse after work, or administrated via a paste. When giving electrolytes,
always remember to be sure the horse also has access to clean, fresh
water. Providing electrolytes in your horse's water bucket will mean
providing a second bucket with fresh water to ensure that the horse
can properly balance its water/electrolyte concentration.
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When
provided with quality feed, sufficient forage and free choice trace
mineralized salt, most horses will not require additional electrolyte
supplementation. |
Feed
concentrates also provide some potassium, and most electrolyte products
contain potassium, however, the horse's major source of potassium
is forage. Most hays and pasture grasses provide 1.5 to 2.3 percent
potassium. Under normal circumstances, horses fed adequate amounts
of forages will not need potassium supplementation. The exception
might be the horse worked intensely in hot, humid conditions. In these
situations, potassium supplementation, especially after exercise,
is important. Relying on the forage to meet the horse's potassium
needs under these conditions in not recommended.
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Endurance
horses, that is, those that are in training for distance events and
horses competing in three-day event activities should be given both
water and electrolytes during training and competition. Most electrolyte
products provide salt, potassium chloride (lite salt), calcium chloride,
magnesium chloride, glucose, and perhaps some other minerals as well.
The glucose is added because it improves sodium absorption and palatability.
The amount of electrolytes needed by the working horse daily will
vary with the individual horse, the activity level, and the environmental
conditions. Each horse owner must monitor his or her horse carefully
and administer the amount that seems to suit the individual horse.
Start with 50 g. of supplemental electrolytes and add increments as
necessary to meet your animal's needs.
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Table
1. Influence of exercise on sweat loss and mineral loss in
horses
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Light
Work
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Moderate
Work
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Intense
Work
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| Sweat
loss, L |
2.5
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10.0
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25
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| Calcium,
g |
0.48
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1.9
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4.75
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| Phosphorus,
g |
0.55
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2.2
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5.5
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| Sodium,
g |
8.25
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33.0
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82.5
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| Chloride,
g |
15.25
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61.0
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152.5
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| Potassium,
g |
4.5
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18.0
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45.0
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| Magnesium,
g |
0.30
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1.2
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3.0
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1
Based on Meyer, 1987.
2 The amount of sweat loss is also influenced by the ambient
temperature and humidity. |
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Horses participating
in endurance type events can benefit from electrolyte supplementation. |
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Conditions
that could require electrolyte supplementation.
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Intense
Work such as racing or endurance training
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Horses
that sweat profusely
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Abnormal
Stress such as trailering in hot weather
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Performing
work in hot & humid conditions
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Relocation
of horse to a tropical climate
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Harder
work than horse is accustomed too
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Feeding
straight oats or other non-commercially prepared
mixes
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Diarrhea
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Sodium Bicarbonate,
an additive commonly included in electrolyte formulations,
can influence performance and supplementation is prohibited
in many equine organizations.Seminole Rebound Electrolytes
do not contain added sodium bicarbonate.
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