Maintaining Hydration and Electrolyte Balance in the Performance Horse
Can a new process called Performance Profiling help you find the optimal regime?
by Gayle Ecker
Severe dehydration and electrolyte deficits can be a
life-threatening occurrence for the horse. However, did you know that even
minor dehydration and electrolyte deficits can have a negative impact on
performance? Let’s look at an example.
For human distance runners, running pace is slowed by 2% for every 1% loss of
body weight due to dehydration. A runner capable of running a
10,000 metres in 35 minutes may be slowed by 2
minutes and 48 seconds. That’s well out of the top ten!
If this decrement in running performance is applied to an endurance horse capable of a nine-hour 100-mile ride,
then a 4% loss of body mass (an average loss seen on most rides) could increase
ride time by about 45 minutes. Many horses are dehydrated by 5-8%, so this
could increase ride time by over one hour, and maybe out of the top ten!
Often fluid and electrolyte losses can be profound. If not
corrected, these may develop into serious complications for the horse with the
added stress of continuing the performance or trailering
home afterward. For the owner,
maintaining hydration and electrolyte status has been mainly a guessing game.
When the guesses are wrong, the results range from mild impairments to
performance, to catastrophic consequences to the health of the horse. Obtaining objective information on the
hydration and electrolyte balance in the healthy equine athlete can be a very
useful tool for helping your horse to achieve optimal performance. These
objective data may be used to detect a level of dehydration or metabolic stress
that is not readily evident nor quantifiable at the
vet checks.
What is Performance Profiling?
The purpose of performance profiling is to help the rider
find the optimal management routine to bring out the top performance of their
horse consistently and safely. Objective
information can be used to help develop improved methods of maintaining fluid
and electrolyte balance before, during and after exercise or transport. This provides valuable information to the
owner of the performance horse — information and learning obtained in one ride
can be applied to the same horse on subsequent rides throughout the season. To
a lesser degree, improvements in fluid and electrolyte management obtained on
one horse can be applied to other horses in that rider’s/owner’s care. With objective information, the owner can
increase the chances of the horse to perform better and more consistently,
while taking away much of the guesswork.
Here is how it works: at an event or training session,
jugular vein blood is sampled before, during and after the event, along with
body weights. As well, sweat may be collected during exercise for analysis
during a training session. The blood and sweat are analyzed and the data
assessed by Lindinger and Ecker
together with the weight changes.
A complete, personalized report and interpretation are
returned to the owner along with suggestions that will help improve performance
and maintain health, usually within 3 weeks of the event.
What kind of information can be provided to the owner?
A track coach will monitor the body weight, condition and
hydration status of his or her athletes, because it is well known that small
improvements in this area can result in large performance increases.
Performance profiling helps provide objective information about the hydration
and electrolyte status of the healthy performance horse during training or
competition. Areas for improvement can
be identified and relayed back to the owner. Changes in feed, electrolyte
supplementation and feeding methods may be identified so that the horse can
better reach its potential. Here are some specific results that have been
obtained from endurance horses in the past.
The weight of the horse in Figure 1, below, was obtained
prior to and after transport. Blood
samples were measured for electrolytes and hydration status was determined from
body mass and blood parameters. The
information obtained from the performance profiling was provided to
veterinarians on-site to help the horse recover from transport. As seen from Figure 1, this horse lost close
to 30 kg of mass during transport, equating to a decrease in total body water
of 26 liters (over 6 gallons!). The veterinarians were able to help this horse
by providing fluids (over 10 L) to help replace the losses that occurred during
transport. Even with overnight recovery,
this horse still had a water deficit of 20 L prior to the start of the
ride. Unfortunately, the intervention of
the veterinarians was not enough after such a long period of water loss and the
horse was pulled midway through the ride. As a result of the profiling, the
client received valuable information to improve management during transport for
subsequent trips. Due to these changes, the horse has now arrived at the
competitions in far better shape with improved performance during rides.
Figure 1: Weight of an endurance horse prior to transport
(pre-trans), after transport (arrival), and following administration of oral
fluids. Weight was taken before the ride
(pre-ride), during (at Vet Check 1 and 2), and after an endurance ride. The horse was pulled before completing the event
due to metabolic concerns. Weight was
obtained when the horse was pulled and then again at one-hour recovery and
again the following morning. Weight is
given in kilograms, where 1 kg = 2.202.lbs = 1 liter of water.
Here is another example of the value of performance
profiling during competition. The graph
to follow shows the calculated extracellular fluid
sodium content decreasing during the ride despite electrolyte supplementation.
The plasma sodium concentration was relatively unchanged, indicating a balanced
water and sodium chloride loss in the sweat; therefore plasma ion
concentrations alone do NOT provide adequate information on the horse’s total
electrolyte balance. Because of the progressive decrease in sodium content that
occurred during the ride, despite the provision of electrolytes and water,
“designer electrolytes” were developed for this horse. Additional sodium
chloride was suggested and implemented, and the improvement in performance was
noted enthusiastically by the rider at subsequent rides.
Figure 2: Sodium content (moles) of the extracellular
fluid compartment before starting the ride (pre-ride) and at the vet checks
(VC1 and VC2) and at the finish. Sodium
content continued to decrease during the ride, despite electrolyte
supplementation.
Sweat samples have also been collected for horses and
analyzed for sweat electrolyte composition.
Although there is an “average” profile, there are many individual
differences. Sweat analysis helps the rider to develop a more effective program
to manage the electrolyte and water supplementation in the exercising
horse. See the example below.
Figure 3: A
comparison of two horses against the average value for sweat electrolyte
concentrations. Concentrations are in mmoles/litre.
In Figure 3, horse A (the second bar of each cluster) is the
same horse as shown in sodium content graph (Figure 2). The sweat of horse A
contains higher than average amounts of sodium per litre
of sweat, leading to a greater depletion of total body sodium than for other
horses with the same sweat loss. Based on this information, the rider increased
the sodium chloride content in the electrolyte supplement. The rider has reported better hydration
during performance and faster recoveries. The sweat of horse B (the third bar
of each cluster) is higher than average for potassium. Based on this information,
the researchers made recommendations to the rider to adjust the electrolyte
supplement, increasing the amount of potassium chloride (lite
salt) during times of heavy sweating.
Part One of this article explains
the basics of performance profiling and how it is done along with an example of
some of the results. In part two,
examples from the FEI Biltmore Challenge 100 mile ride will be presented with
lessons that can help all horses.
For more information contact Gayle Ecker
at The Equine Performance Group,
There seems to be nothing quite as satisfying as giving our
horses a tub full of grains and sweet feeds, and a big pile of all of the hay
they can eat. Are we doing them a favour,
or killing them with kindness? Part of the answer depends upon the kind of
activities that you and your horse participate in. Certainly, for the leisurely
trail horse, you probably don’t have a big concern, other than weight control.
But what if you compete in endurance competitions or enjoy a cross-country
gallop in the afternoon? There are certain techniques that may be worth knowing
to keep your horse competing at his best possible level and happy at the same
time.
The first thing to remember is that horses evolved as
grazing animals that existed almost exclusively on forages. They ate almost
constantly. Wild horses graze for close to 13 hours each day. We now generally
expect our horses to stand in a stall, and to eat two or three meals a day that
are made up of concentrates (concentrates include any feed stuff that isn’t
forage, including sweet feed, oats, corn, pelleted
feeds, extruded feeds, etc.). Sometimes, we even restrict the forage intake.
Understanding the Digestive Process
Let’s take a look at the first most obvious issue that could be a problem. If a horse is fed his hay in isolated meals, as opposed to letting him ‘graze’ or pick at his hay all day, he will tend to bulk up quickly. This increased mass and weight can be detrimental if the horse is then asked to exercise. What happens is that in order to chew and digest the forage, a horse produces a large amount of saliva, and the digestive juices increase in volume in the gut. This causes a drop in plasma volume, by as much as 1/4 of the normal amount present, and a resulting increase of the total proteins in the blood, making him thirsty. If left alone, the horse will generally rehydrate himself by drinking after he is done eating, but this takes some time. If you ask your horse to exercise before he has rehydrated, it could lead to problems. Low plasma volumes can interfere with the body’s ability to cool itself during exercise, and can also cause an increase in heart rate due to the fluid relocation. Remember when your mother told you not to swim or play on a full stomach? I guess she knew what she was talking about!
Now, most of us also feed those large tubs of concentrates. If they are fed at the same time as the forage, problem number two occurs. Because of the increased saliva needed to chew and digest the forage, there is a faster rate of passage of the concentrates. They then have a greater chance of being washed into the hindgut. This is not the favoured site of digestion for carbohydrates, the main component of most concentrates.
Certain forms of concentrates have faster rates of passage
than others. Small pellets that do not require much chewing are the fastest to
be ingested, with extruded feeds being much slower. Forage products have the
slowest rate of ingestion. Chewing, itself, is
essential to maintaining the balance of acidity in the digestive tract. The
saliva produced acts as a buffer to the naturally occurring acids in the
system. Since forage products require the most “chew time”, this is just one more
reason to feed high fibre diets. (As an aside, it is
also important to maintain the condition of your horse’s teeth, as chewing
becomes difficult when the grinding surfaces are not properly aligned. Teeth
should be checked at least once a year by your veterinarian.)
Is Feeding Sequence Important?
Carbohydrates are ideally eaten in small amounts, on their own, and then digested in the small intestine. If they pass into the hindgut, the site of roughage (forage) digestion and fermentation, trouble is just around the corner.
Large amounts of soluable carbohydrates absorbed in the hindgut cause the production of a high level of lactic acid, a natural by-product of digestion. When lactic acid is present in the hindgut, it causes a decrease in pH (the level of acidity) and can result in the onset of colic (not to mention laminitis). This improper digestion also results in an increase in plasma lactate, not a good thing for exercising horses. Even worse, there is an improper breakdown of the starches (from the carbohydrates) and therefore the full benefit of using them as a glucose source (energy) is not achieved. Contrary to what we have always been taught, it isn’t necessarily good to feed the forage first and then the concentrates.
Feeding a large grain meal doesn’t cause the same displacement of fluids as a large forage meal does, but there is another side to this feeding dilemma. Large grain intakes (some performance horses eat over 8 pounds of concentrates each meal) can cause some huge changes in the horse’s blood chemistry. Once a horse ingests a large meal of concentrates, his body is in what is called an anabolic state. This means that the body, specifically insulin, is working at distributing the circulating glucose to where it is needed. Insulin is always released shortly after the glucose levels peak in the blood. Both glucose and insulin peak at about ninety minutes after a meal, but the actual anabolic state continues for close to eight hours. This cyclical response is seen only in grain-fed horses. Horses that eat predominantly forage diets have a more level profile throughout the day, with less pronounced peaks of glucose and insulin.
There is also what is called a catabolic state. This is when
the horse’s prolonged lack of fuel (glucose) triggers the response to mobilize
stored energy. This state doesn’t usually occur until about 24 hours after a
meal, hence there is a fairly large window of opportunity to work with. The
ideal is to achieve a balance within the body.
In some research trials that were conducted, horses fed grain three hours before work showed peaks in glucose and insulin before exercise and then a rapid plunge during exercise (not a good thing). These horses never returned to the same levels during exercise as horses that were fed forage diets and then exercised. After exercise, the grain-fed horses again showed higher levels of glucose and insulin than non-grain fed horses. There was also a drop in circulating free fatty acids, another energy source (from forages). What happens here is that the insulin is tricked into thinking that there is enough glucose (energy) circulating in the blood to meet the body’s demands from exercise.
This all said, the biggest effect of feed timing on a horse’s performance will usually only be seen in horses that are subjected to large challenges on energy utilization. This includes endurance horses, three-day eventers, field hunters, etc. These horses have to go both long and hard for most of the competitive day. Conversely, racehorses, though competing at great speeds, really only have a short time when these great demands are made on their bodies. That open window of opportunity between anabolism and catabolism is usually wide enough to cope with reasonable energy demands.
Extra Benefits from Optimal Feed Timing
The feeding patterns are important for other reasons as well as evening out energy availability. Small, regularly fed meals reduce the risk of ulcers. The majority of high performance horses have ulcers, which can cause any number of problems, from reduced nutritional absorption to varying degrees of digestive upset or colic. It has also been shown that stress decreases when adequate amounts of forage are being fed. The horses actually have something to do (don’t forget that they are genetically programmed to graze for thirteen hours each day) so the forage availability reduces boredom. The saliva that is produced from chewing the forage also acts as a natural buffer against the acids in the stomach.
Basic recommendations for all horses include keeping hay (or pasture) available as constantly as possible. Even small amounts can help reduce stress. Even prior to a performance, these small amounts won’t cause the heaviness, bloating and fluid displacement we talked about earlier.
Feed your grain/concentrate portions of the diet first, at least eight hours before a performance. Don’t feed the hay until a short while after the concentrate meal has been consumed, giving it time to be properly digested in the small intestine.
There is one more interesting tactic that can be used: feeding fat. In research trials, adding fat to the diet decreased the glucose and insulin peaks of horses that were fed 3 hours before exercise. There is a scale that has been developed that is a measure of how much glucose enters the blood at 90 minutes after a concentrate meal is fed. It is called a glycemic index and it is applied to different feed stuffs to rate them against one another. Oats are used as the basis, with an index of 100. Sweet feed has an index of 130, while corn is just 80. In sweet feed the higher number is due to the molasses (sugar) that is added to the mix, and the lower number assigned to corn reflects the fact that corn is harder to digest because of the fibrous seed coat. What is really interesting is that by adding fat to a sweet feed ration, you can cut the glycemic index to less than half that of the sweet feed alone. This means that the horse’s glucose peaks will be lower and more even throughout the anabolic period.
The bottom line: feed your horse using common sense. Keep
his meals, especially the forage portions, small and as frequent as possible.
Allow him time to properly digest the concentrate portion of his diet. Try
using added fat as a way to smooth out those peaks of glucose and insulin. The
goal is for even energy availability throughout the day to keep your horse
happy and competing at his best level possible.
Buckeye Nutrition, of
Performance profiling is an assessment method developed by
Gayle Ecker and Mike Lindinger
for assessing the hydration and electrolyte balance and metabolic status of
healthy performance horses. This can be done before, during and after training,
competition or transport.