Due to the increasing interest in the benefits of electrolyte
supplementation for endurance horses we have decided to address
several concerns and questions that have come up over the winter
Since most of the (good) questions have come from people on this
list, we have decided to send this to you first! We hope that you
both enjoy and find this information useful. Please feel free to
share this info with whomever!!
Also, we welcome your continued feedback and questions, and your
We heartily wish you all a very successful, fun and healthy riding
Sincerely, Gayle and Mike
Our contact numbers are at the end of the document.
The Development of Perform' N Win:
an Electrolyte Supplement for the Performance Horse
Perform'N Win (PNW) is an electrolyte supplement that is specifically formulated to
replace electrolytes (salts) lost in the sweat of horses during the time that they are working. The
electrolyte product, manufactured and distributed by Buckeye Feeds, Inc. of Ohio, was developed
and tested by Michael I. Lindinger and Gayle Ecker, researchers in equine exercise physiology at
the University of Guelph and the Equine Research Centre.
When horses are exercising, heat builds up in the working muscles. The body attempts to
avoid serious elevations in core temperature by dissipating the heat. During exercise, the most
important route of heat loss is through the mechanism of sweating, where fluid is secreted to the
surface of the skin. The sweat of the horse is very high in salts or electrolytes. The main salts
lost in sweat are sodium (Na+), chloride (Cl-) and potassium (K+). Measurable amounts of calcium
(Ca++) and magnesium (Mg++) are also found in sweat. Horses performing very hard work can
lose more than three (3) gallons (or 12 L) of sweat in 1 hour. It is more usual that they lose 1
gallon (or 4-5 L) of sweat during 1 hour of moderate work when ambient temperature is between
50-70oC. With hot, humid conditions the sweating rate can double, with losses of 2 gallons (10
L) or more per hour.
One U.S. gallon (~4 L) of sweat will contain 1800 to 2400 mg of sodium, 1000 to 2000
mg of potassium, 3500 to 5000 mg of chloride, 60 to 100 mg of calcium and magnesium. The
corresponding molar concentrations are: sodium 80 to 100 mmoles/liter, potassium 20 to 40
mmoles/liter, and chloride 100 to 140 mmoles/liter.
One ounce (28.4 grams) of Perform'N Win dissolved in 1 liter of water gives a solution
consisting of 50 mmoles/liter of Na+, 25 mmoles/liter of K+ and 80 mmoles/liter of Cl-. These
concentrations are much less than those found in sweat for a very good reason. Equine sweat is a
highly concentrated solution of salts. If horses ingested such a concentrated salt solution, it
would be difficult and inefficient for the intestine to absorb the salts and water. In fact, water
would initially be pulled into the intestinal system from the blood, effectively dehydrating body
fluids. Therefore, to adequately replace all of the electrolytes lost in one gallon of sweat the horse
should drink 1.5 to 2 gallons of Perform'N Win solution (made up with 4 ounces PNW per
gallon water). The extra water will be beneficial for increasing body water turnover, improve
renal function, ensure complete rehydration and the kidneys will normally excrete the excess.
WHERE DO THE SALTS IN SWEAT COME FROM?
The salts lost through sweating come from the plasma portion of the blood, the fluid that
is between all the cells in the body (interstitial fluid), and the fluid that is inside of the cells
(intracellular fluid). Together the plasma and interstitial fluids are termed extracellular fluid
(outside the cells). Most of the sodium and chloride, and much of the water, lost in sweat comes
from the extracellular fluids. Most of the potassium and some of the water comes from the
intracellular fluids (water inside the cells). Fluids within the stomach and intestines
(gastrointestinal or g.i. tract) are also extracellular and may provide a reservoir of water and salts
that can be used during work.
WHY REPLACE SALTS AND WATER LOST THROUGH SWEATING?
The loss of water through sweating and ventilation leads to dehydration. This dehydration
results in loss of water from the blood plasma, interstitial fluids and from inside the cells. This
may compromise the function of cells and tissues, including skeletal muscle, g.i. system, heart and
skin. Typically, the appearance and performance of the horse will suffer, leading to an early
onset of fatigue.
A horse may have a water deficit of 17 to 30 L following a 50 mile endurance ride. This
equates to a 4 to 7% loss in body weight. Research has shown that even a 3% loss (about 13 L)
of water may have a negative impact on performance. Excessive dehydration compromises the
health of the horse and can lead to heat stress, tying up and colic.
The loss of salts impairs the ability of cells to function normally. Muscle cannot function
at optimal levels. For optimal function, it is therefore, important to replace both the water and
salts that have been lost.
When horses are dehydrated, fast effective rehydration best occurs when sufficient
amounts of salts are administered with appropriate amounts of water and carbohydrates. If only
water is given, complete rehydration can take from 12 to 24 hours. Feeding wet foodstuffs can
decrease this time. Our research has shown that horses given 3 ounces of Perform'N Win in 3
liters (3/4 gallon) fully recover hydration status within 45 minutes after the end of 1-2 hours of
moderately intense exercise. The horse that recovers hydration status rapidly will eat better, feel
better, and be less prone to post-exercise fatigue and muscular cramping.
The horse that is prevented from incurring a high level of dehydration during exercise (by
pre-loading Perform'N Win and giving Perform'N Win during breaks in the exercise) will
perform better, recover better and be better able to prepare for the next day's work.
Pre-exercise Loading: Perform'N Win may be given up to 2 hours before work. This provides a
'reservoir' of water and salts in the gastro-intestinal system that we have demonstrated is available
and used during exercise to replace water and salts lost in sweat. An amount of 1 gallon of water
containing up to 4 ounces (114 g) of Perform'N Win would be appropriate for pre-exercise
supplementation 2 hours before starting the exercise.
During Exercise: When exercise or work is to be continued for more than 1 hour it would be
appropriate to encourage the horse to drink freely during breaks in the work. The horse may not
want to drink initially. It is normal for a horse to incur a mild level of dehydration before the
thirst response is stimulated. For horses that are not drinking, the electrolytes should not be
given by syringe (electrolyte/water slurry) into the mouth. The syringe approach may be okay,
but it is important that the horse has ingested at least one gallon of water before administering.
Otherwise, the concentrated solution will pull water into the g.i. tract, away from the other
After Exercise: We recommend that horses that have worked sufficiently hard to sweat be given
about 1 gallon of Perform'N Win solution (4 oz./gallon) for each hour of exercise. This amount
may be reduced if horses were taking Perform'N Win solution during the period of exercise.
This should be given as soon as practical after the end of exercise so as to get a rapid rate of
rehydration and replenishment of body salts. It should be given during the initial 1 to 2 hours after
exercise, the sooner the better. The capacity of the stomach is about 2-3 gallons in endurance
horses and fluid in the stomach empties very rapidly into the small intestine. If the horse is freely
drinking Perform'N Win dissolved in a bucket of water, it is not possible to over-administer.
It is important to try to rehydrate horses as much as possible prior to feeding. We do not
recommend feeding the horse hay and dry feeds until after administration of water and
electrolytes, thus feeding would occur at least 1 hour after the end of exercise. This allows time
for fluid and salt balance to be restored. Dry foodstuffs in the gut will further dehydrate an
already dehydrated horse by pulling water and salts from the blood into the intestine. This will
greatly delay the recovery process and put the horse at risk of developing dehydration related
problems. Exercised horses should eat soaked hay or a grain mixture with added water. It is
important to get lots of water in to the horse during the recovery period.
For further reading:
Ecker, G.L. (1995) Fluid and ion regulation: a primer on water and ion losses during exercise.
Equine Veterinary Education 7(4):210-215.
Ecker, G.L. (1996) Management of horses participating in endurance rides. Compendium on
Continuing Education for the Practicing Veterinarian. 18(5):566-567.
Ecker, G.L. and A. Rogers (1996) Championship Condition. EQUUS 225:54-63.
Lindinger, M.I. and D.J. Marlin (1995) Heat stress and acclimation in the performance horse:
where we are and where we are going. Equine Veterinary Education 7(5):256-262.
Maughan, R.J. and M.I. Lindinger (1995) Preparing for and competing in the heat: the human
perspective. Equine Veterinary Journal (Supplement 20):8-15.
PNW Administration Schedule
2 hours Pre-exercise up to 4 oz. with 1 gallon of water
During Exercise 2 oz. with .5 gallon or more of water
(at 45min to 1 hour intervals)
For 1 hour breaks up to 3 oz. with 2 gallons or more of water
Recovery from Exercise 8 oz with 2 gallons or more of water over a 1 to 2 hour period.
For a 50 mile endurance ride, sweat losses range from 15 to 30 L (4-8 gallons). As an example:
Pre-ride 1 gallon
15-20 miles .5 gallon
25-30 miles .5 gallon plus .5 gallon if 30+ minute hold
40 miles .5 gallon
Recovery 2 gallons
4 .5 gallons + .5 = 5 gallons of PNW solution
I have been told to avoid electrolyte mixes with sugar. Is this a problem with Perform' N
It is true that supplements containing large amounts of sugar should be avoided when
using that supplement before, during or after exercise to replace sweat losses. This kind of
supplement may cause sugar highs and lows. However, a supplement without any glucose (a
simple sugar) will not be absorbed efficiently . There are transporters in the small intestine that
carry sodium, potassium and water, with glucose across the intestinal wall into the bloodstream.
The amount of carbohydrates in PNW (approximately 3%) is balanced to ensure rapid absorption
of sodium, potassium, and water (for comparison, Gatorade has 6% carbohydrates to promote
electrolyte transport in humans). The rapid absorption of the PNW supplement has been
confirmed by research at the Equine Research Centre, by using tracers to follow the absorption of
sodium and potassium. The ingestion of up to 3 ounces of PNW in 3/4 gallon of water will not
cause sufficiently large increases in plasma glucose to get a sugar high. It is recommended that
during exercise, not more than 2 ounces in 1/2 gallon water be administered at once.
Why can't you make it into a paste?
Some supplements are sold as a salt paste. This highly concentrated material in the
stomach will empty much more slowly than water. It may take twice as long to be emptied into
the intestine and the recovery process is delayed considerably. Also some pastes are
manufactured in a corn syrup (high sugar) base and as mentioned above, high sugar intake is not
recommended for the horse during exercise. These pastes also cause dehydration of body fluids
unless given with adequate amounts of water.
We do not recommend using salt pastes during exercise as they disturb the fluid balance of
the horse. This has been confirmed by a team in Sweden (Nyman et al.) doing research on
endurance horses during competition. They recommend against using salt pastes before and
Can I make my own recipe at home for less money?
Yes, you can. However, the ratio of salts, the form of salts and the proportions of salts
vs. carbohydrates is important for designing a supplement that will work optimally during
exercise. The PNW resulted in increased time-to-fatigue (~23% longer exercise duration at a
constant speed) when used on horses under controlled treadmill conditions. The study also
showed rapid uptake and distribution into the blood and of K+ into the blood cells and skeletal
muscle. Controlled tests have found this supplement to be effective at quickly restoring water and
salt losses in exercising horses.
Powders in general, and PNW in particular, ounce for ounce are about 10% of the cost of
most commercially available pastes when administered for a given ride distance.
What type of horse is this supplement suited for?
All horses undergoing prolonged (2 h or more) exercise, including training and long walks
in warm weather sufficient to cause sweating. PNW is designed to be fed on a per hour of
exercise basis. This makes it ideally suited to the performance horse. No guessing is needed
about your horse's weight where the dose of the supplement is based on body weight.
How is weight loss related to performance decrements?
The amount of weight lost during exercise is predominantly due to sweat losses. If a 450
kg (1000 lb) horse loses 14 kg (~30 lbs), this means that about 14 L of sweat has been lost, or a
3% body mass loss has occurred. Recent research shows that even a 3% body mass loss can have
a negative effect on performance in horses. A 3% decrease in body mass is equal to about a 5%
decrease in body water (5% dehydration). At the Race of Champions, horses that lost more
fluids (body mass) in the early part of the ride finished at slower speeds than the horses that
maintained their body mass. In other words, a high sweat loss that is not replaced early in the ride
results in a slower ride speed (poorer performance). It is important to keep water and electrolytes
going into the horse, even during the early part of the endurance ride if a strong finish is desired.
Isn't water sufficient? Why do I have to add electrolytes?
Intake of water alone will actually dilute the remaining fluids in the horse, decreasing the
concentrations of sodium, potassium and chloride in the blood. This dilution can be a serious
health concern because it leads to an imbalance of electrolytes and increases the time it takes for
full rehydration and electrolyte replacement. It may also reduce the thirst response, which is
affected by the sodium concentration in the blood. The composition of PNW with electrolytes
and carbohydrates ensures that rehydration occurs rapidly, and the bloodstream is quickly
absorbing the water and electrolytes it needs to recovery. The Na+ is retained in the bloodstream
and the rest of the extracellular fluid where is retains water. The K+ helps retain water in the
muscle and the rest of the intracellular fluids. Testing has even confirmed that the K+ in the PNW
supplement enters the muscle more rapidly than when K+ tracer is given with water. The
maintenance and restoration of K+ and water into the muscle is critical for opti
mal and continued
Do I need to give electrolyte supplements during the week when training?
If your work-outs cause sweating that lasts for more than one hour each day, then using
PNW in the water after your workouts will aid in faster recovery. PNW is not designed as a daily
all-purpose electrolyte supplement, but many like to use it during the week as well as during
competitions and training to maintain consistency.
Can I give PNW in any other manner?
Yes, as long as you know the hydration status of your horse. If you prefer to administer
the PNW as a slurry or paste by syringe directly into the mouth, only do so after the horse has had
a good drink. PNW can be given in the feed in morning for pre-loading. We know of one
endurance rider that makes PNW "cookies" to give his horse during the endurance competitions.
As such, they can be useful "rewards" for the horse AFTER the horse has had a drink of water.
They could also be used at home to "train" the horse to drink.
Do I need to give my horse electrolytes on short rides (<30 miles)?
The answer to this question depends on the conditions. If it is hot and humid, then giving
your horse PNW will help the horse during exercise and to help enhance the recovery. Even
though the distance may seem short, if the speed is higher, or it is hot and humid, the horse can
still lose more than 20 L (5 gallons) of water.
Will horses get enough salt from a salt block to replace the sweat losses?
If your horse is sweating more than 2 hours a day, then it is unlikely to get enough salt in a
short period of time. Salt blocks are made for cattle. The horse may not be able to lick enough
salt to replace the losses. This is frequently why you see horses chewing or scraping their teeth
on the salt block to get more. Providing free choice loose salt can help avoid this problem. Also,
some of the blocks contain other minerals and substances. If the horse licks or chews the block
enough to satisfy the sodium requirements, it may be getting too much of the other minerals that
are not lost in sweat.
Isn't it bad to give the horse electrolytes during the week? Don't we make the horse lazy in
Electrolytes cannot be "saved" or "stored" for long periods. The only way we know of to
"store" electrolytes is to put them into the g.i. tract, with water, before exercise. There is no evidence
to show that giving a horse electrolytes during the week makes him "lazy" during the
endurance ride. In fact, the opposite may occur. If the horse is lacking in electrolytes from the
hours of training, it may be in a fluid and electrolyte deficit before the ride even starts. The loss of
water and electrolytes is an obligatory result of heat dissipation. These losses, if not replaced, can
negatively impact on the performance and health of the animal.
For more information:
Gayle Ecker can be reached at: e-mail: email@example.com
Mike Lindinger can be reached at: e-mail: firstname.lastname@example.org
phone: 519-824-4120, ext. 3752.
Michael I. Lindinger
Dept. of Human Biology & Nutritional Sciences
University of Guelph, Guelph, ON Canada N1G 2W1
Phone: 1 519 824 4120 ext. 3752
FAX: 1 519 763 5902
University home page: http://www.uoguelph.ca/