3
UNDERSTANDING SWEAT
Sodium
Potassium
Sodium is essential for nearly every process in the body. Because
of this, the horse’s body is very good at preserving sodium and will
sacrifice other electrolytes such as potassium in an effort to maintain
sodium levels.
Potassium is essential and important for the maintenance of internal
pressure in the cells and in association with sodium can influence
nerve and muscle functions. In an attempt to preserve sodium, the
horse’s body will excrete potassium instead. Horses’ diets often
do not contain enough potassium. A performance horse requires
approximately 50 grams of potassium per day whilst an average ration
of hay may only provide 20 to 30 grams to the horse.
Why is providing fresh water so important when
supplementing with electrolytes?
Sodium plays the very important role of controlling the amount of
water in a horse’s body at any one time. Water is attracted to sodium
and will follow it around. The horse’s body will work hard to keep the
sodium/water concentration constant. When we correctly supplement
sodium, we increase the sodium concentration to water and this
engages the horse’s thirst drive encouraging it to increase its water
intake. This is vital in maintaining hydration.
Horse sweat is very concentrated, making an overall change in
the blood and tissue electrolyte concentration very subtle. These
subtle changes in concentration may be inadequate for the horse’s
‘thirst sensors’ to detect large losses of fluid (in the form of sweat)
and hence fail to drive thirst. If the body does not detect that it has
lost large volumes of fluids and electrolytes this can lead to further
dehydration. By supplementing with electrolytes high in sodium the
balance is redressed and thirst is driven.
Chloride
Chloride is a negatively charged ion which is attracted to positively
charged ions such as sodium and potassium. Chloride is the
electrolyte which is lost in the greatest amount in heavily sweating
horses. Chloride and bicarbonate play important roles in maintaining
the acid/base balance within the body. Loss of chloride can upset this
balance leading to changes in blood pH (hypochloraemic alkalosis).
Such changes have a detrimental effect on normal body functions
and, if severe, can even lead to coma and death.
Calcium
Calcium is an important electrolyte and major component of bones
and teeth. It is required for the maintenance of normal heart rhythm,
blood clotting, muscular contractions and other metabolic activities.
Phosphate
Phosphate is a key component in energy production and protein
metabolism as well as playing its part in the structure of bones.
Magnesium
Magnesium is a co-factor in numerous enzyme systems, involved
in energy production, muscle contractility and nerve transmission.
Horses low in magnesium often become nervy due to an absence of
the stabilising effect magnesium has on nerves.
Bicarbonate
Bicarbonate assists the body by mopping up excess acids such
as lactic acid produced during intense exercise before it can cause
damage to the muscles. It is known as a ‘buffer’. A buffer is a weak
acid or alkali that assists the body in regulating pH.
THE IMPORTANCE OF EQUINE ELECTROLYTES
VIR049 - SOS_20ppBrochure_2014ed.indd 3
11/09/14 6:41 AM
4
UNDERSTANDING SWEAT
Bicarbonate and swabbing
Excess bicarbonate in the body is thought to have performance
enhancing effects. For this reason an upper acceptable limit has
been set by the majority of competition jurisdiction bodies. Provided
bicarbonate sources are fed according to the manufacturer’s
instructions and the practice of pre-race drenching is avoided, it is
unlikely that one would exceed these limits.*
CALCIUM 0.3g
Some sodium is
reabsorbed back
into the horse’s
body taking water
with it and leaving
a concentrated
sweat solution
to evaporate on
the skin.
VESSEL
BLOOD
PROTEIN CALCIUM
PHOSPHATE
SODIUM (Latherin)
MAGNESIUM CHLORIDE
WATER
POTASSIUM
PHOSPHATE 0.14g
POTASSIUM 1.4g
WATER
A ND
GL
Electrolytes lost in a litre of sweat
SODIUM
Latherin helps
to spread sweat
into a thin film
across skin aiding
evaporation and
cooling.
T
EA
Glucose is a simple sugar used as an energy source within the body.
Together glucose and sodium are actively pumped into the body by a
transporter pump to aid/speed their absorption process. The practice
of adding glucose to electrolyte preparations assists with the rapid
absorption of sodium.
SKIN SURFACE
SW
Glucose
WHAT HAPPENS TO A HORSE’S
BODY WHEN IT SWEATS?
MAGNESIUM 0.1g
IRON 0.24g
To expel heat, the
blood transfers
electrolytes and
water into the
sweat gland to
produce diluted
sweat.
The Sweating Process
PROTEIN 2.5g
CHLORIDE 6.2g
SODIUM 3.2g
As the concentrated sweat solution leaves the body and
evaporates, the horse’s electrolytes supplies are depleted. If the
horse does not have enough stores, or if the electrolytes lost are not
replaced immediately, reduced functionality occurs leading to poor
performance and lack of stamina.
Sweat loss is determined by three factors:
*Owners are advised to seek advice from relevant authorities and nominated veterinary
surgeon. Individual circumstances and metabolic changes may result in positive swab
results. In thoroughbred racing, it is against the rules to administer any alkalising
agent, by any means, during the one ‘clear day’ prior to race day.
1.Exercise intensity
2.Exercise duration
3.Climatic conditions
The longer a horse sweats, the greater its electrolyte losses.
THE SCIENCE OF SWEAT
VIR049 - SOS_20ppBrochure_2014ed.indd 4
11/09/14 6:41 AM