Your horse may need electrolyte supplementation after stressful work.

Whether it’s summer or winter, your horse’s major source of electrolytes/minerals is his basic diet. For example, the daily potassium requirement of a 1,000-lb. horse doing intense work is about 40 grams per day. Most hays contain a minimum of 1% potassium, so 10 lbs. of hay a day will meet or exceed the potassium needs of a horse at work and 5 lbs. of hay will keep a horse at mainetance (1 lb. of hay provides 4.5 grams of potassium).

Of all the important electrolytes/minerals, the only ones that aren’t present in adequate amounts in the diet are sodium and chloride—that’s plain old salt.

Salt: the Major Concern
At baseline, the horse needs to take in approximately 1oz. of salt a day to stay optimally hydrated. Sodium is the major mineral controlling how much water is in his body. Because it’s in such short supply in their diets, horses have evolved to have a strong hunger for salt, and their bodies will also save sodium at the expense of losing other minerals if they have to.

When sodium is in short supply, horses adjust by secreting less sodium in the urine (substituting potassium instead), producing more concentrated urine, and “robbing” the tissues surrounding the cells of water to preserve the volume of their circulating blood. This loss of water in the tissues is what makes a dehydrated horse’s skin stay tented up away from his body if you pinch it.

Horses that have not had access to salt can maintain their circulating blood volume well, but they’re always somewhat dehydrated. If they never get stressed or exercised they’ll probably be OK, but they quickly get into trouble with overheating, heat stress and serious electrolyte abnormalities if temperatures climb or they’re worked.

The major error that people make when using electrolyte supplements is to ignore the horse’s basic salt requirement and think the electrolyte supplement is all their horse needs. This simply is not the case. Most supplements contain far too little sodium to even begin to meet the baseline requirements. Horses still need salt.

Another common mistake is to add them to the horse’s drinking water without also providing plain water. Some horses don’t like the taste of electrolyte products or have mouth sores/ulcers/abrasions that are irritated by the electrolyte-spiked water. Horses with stomach ulcers may avoid electrolytes, too. The horse will also stop drinking supplemented waters once their sodium hunger has been filled. The result of any of these things can be that the horse doesn’t drink enough plain water.

Easy Electrolytes
The first step in making sure your horse has an adequate intake of electrolytes is to feed him a mineral-adequate diet with 10 lbs. of hay/day.

The next step is to provide free-choice salt or add salt directly to feeds. If you provide salt free-choice, monitor how much the horse actually eats. Loose salt, either in granular or fine form (e.g., table salt with/without iodine), will usually be consumed more readily than salt in licks or bricks.

Make sure that the horse consumes at least 1 oz. of salt per day in cool weather, when inactive. That’s a pound of salt every 16 days. With hard work (sweating) and warm or hot weather, the horse’s salt needs will increase to 3 to 4 oz./day for an average-size horse.

Deciphering Electrolyte Labels

To make sure you are buying primarily an electrolyte supplement, not a lot of fillers, look for the amount of chloride to be 45 to 50%. This amounts to 12.78 to 14.2 grams of chloride per ounce. If significantly below this, it’s diluted. Look for sodium around 6 grams, potassium 4.8 grams. If the label lists a percentage as salt, look for 75 to 83% salt. If the label lists ingredients as their salts, e.g. Potassium chloride, sodium chloride, look for one that has 2.5 to three times more sodium chloride than potassium chloride. Look for sodium to be somewhat more than half the level of chloride. If sodium and potassium are listed separately, potassium should be 80% of the sodium level, e.g. if  5 grams sodium, you want 4 grams potassium. Don’t be swayed by flavorings. Horses have a natural taste for salt. All the flavored products still basically taste like salt (unless heavily diluted with sugar or other fillers) regardless of what they smell like. When comparing products that list their ingredients differently—by percentages versus grams and mg—some easy math to remember is that a level of 10% in a 1-ounce serving = 2.8 grams. 10% in a 2-ounce serving = 5.6 grams, etc.

Supplements
There’s a place for electrolyte supplements, but it comes after you’re sure the horse’s baseline requirements for minerals in the diet and plain salt have been met. It can’t be stressed often enough that failure to provide the horse with a balanced diet and to meet his minimum-salt requirement of at least 1 oz. per day, whether working or not, will get you into trouble that electrolyte supplements can’t fix.

Prolonged exercise (e.g., endurance rides) or shorter periods of intense exercise (racing) can result in large losses of sodium, potassium and chloride in the horse’s sweat. Since it’s really not possible to “preload” the horse with extra electrolytes before the exercise starts, he’ll have to make up those losses after exercise (and during, for horses that work all day). This can be done if your base diet is adequate, including adding more salt to make up for sweat losses, but it can take a day or two for heavy water and electrolyte losses to re-equilibrate.

To prevent losses piling up in horses being worked regularly, and to avoid performance effects from losses during exercise happening faster than the horse can replenish them from what’s available in the gut, electrolyte supplements are useful. To replace losses accurately, the supplement should have the major electrolytes sodium, potassium and chloride present in proportions that mimic those of sweat.

Sweat contains approximately 80% as much potassium as sodium and twice as much chloride as sodium. The quantity of electrolytes the horse needs depends on how much sweat he loses. Sweat losses during exercise vary, from about two quarts to over 10 qts./hour. In terms of sodium lost, this amounts to anywhere from 5 to 25 grams/hour.

Bottom Line
Unfortunately, most electrolyte supplements don’t come close to making up for the losses the horse has in a one-hour period. Our pick for concentration of electrolytes/oz, price and correct balances is Peak Performance’s Natural Balance Electrolite.

Mobile Milling’s Exer Lyte noses out Gateway’s Su-Per Lyte for Best Buy, requiring just a bit more potassium for ideal balance to match sweat, primarily a consideration for horses working for prolonged periods in high heat.

What Are Electrolytes?
Every cell in your horse’s body acts like a tiny battery, highly dependent on the correct concentrations of electrically charged particles  both inside and outside the cells. These charged ions are electrolytes.

Electrolytes are nothing more than minerals dissolved in the horse’s blood stream. The horse must take in electrolytes/minerals year round to replace those lost in urine, saliva, bile, tears, mucus, intestinal-tract secretions. Electrolytes are also lost in sweat, but the sweat losses are only part of the horse’s total daily needs.

The major electrolytes in blood are sodium and chloride, which together make salt. Inside cells, potassium substitutes for sodium. Other important electrolytes (minerals in free/dissolved form) include calcium, magnesium, and phosphorus, and the trace minerals zinc, iron, copper and manganese.  Bicarbonate ion is also an electrolyte. Your horse manufacturers this in a reaction that combined water and carbon dioxide to form hydrogen ions and bicarbonate ions.

Checking for Dehydration
There are two simple tests you can do to check how well-hydrated your horse is. One is called the “pinch test.” Pull up a fold of skin on your horse’s neck and tent it away from the body. If the horse is well-hydrated, it will immediately snap back into place. If the skin is slow to return to its normal position, the horse is somewhat dehydrated. The longer it takes, the worse the dehydration. In older horses, loss of normal skin elasticity can make this test unreliable when done on the neck. In an older horse, you should tent the skin at the point of the shoulder instead.

The other test is to lift the horse’s upper lip and press your thumb on the gums over the teeth with enough pressure to make them blanch to white. This compresses the blood vessels. In a horse with normal hydration, the color will return in less than two seconds. Any longer than this means the horse is dehydrated. With severe dehydration, the gums will also feel dry and tacky rather than moist and slippery.

Planning for Exercise in the Heat
Heat stress/exhaustion can be a life-threatening complication of exercise in hot weather. Even relatively small amounts of dehydration and electrolyte imbalance have a negative effect on muscle function and can cause problems like thumps, poor intestinal motility, even heart arrhythmias.

While you can’t start your horse’s work day with extra electrolytes in the body tissues (the kidney rapidly clears any excesses), you can make sure he at least starts the day with his tank full and a reserve ready for absorption in his intestine by following these steps:

1) Feed at least 10 lbs./day of hay, or allow constant grass access.

2) Give a minimum of 3 oz./day of plain salt, half divided between feeds, half syringed in after meals. Do this routinely, or at least starting three days before a day of planned heavy exercise in the heat.

3) Avoid excessive calcium feeding. This can reduce the horse’s ability to mobilize calcium from storage depots in bone if he needs it during exercise.

4) If the horse is only sweating lightly, replace these losses with 3 to 5 grams of sodium and appropriate levels of chloride and potassium for every hour worked. For heavier sweating, double the above amounts.

5) Get up early enough that your horse has a chance to eat a normal breakfast, including hay or grass, and to drink before exercise starts.

6) If the horse will be working hard all day, give the first dose of electrolytes before exercise starts. This helps to match absorption to losses so that deficits do not occur.

Note: For optimal absorption, during exercise provide no more than about 1.5 grams of sodium and appropriate matching amounts of potassium and chloride per gallon of water consumed. A horse with a normal body level of sodium will drink freely. If you follow the steps above, your horse should easily drink enough water to allow for the hourly supplement amounts suggested, but it’s still advisable to monitor water consumption between dosings to make sure that he does.

Equine Electrolyte-Related Performance Problems
Muscular: Both dehydration and electrolyte abnormalities interfere with the ability of the muscle to contract normally. Overheating secondary to tissue dehydration also interferes with function and may damage the muscle cells. Consequences range from poor performance and fatigue to overt muscle damage and tying-up.

Heat Stroke/Exhaustion: Dehydration severely impairs the horse’s ability to cool down his body. If forced to continue working, body temperatures may climb to 106° or above. This is a genuine medical emergency that may take your horse’s life if not promptly treated.

Thumps: Electrolyte abnormalities (usually low levels of calcium, magnesium and/or potassium) cause nerve irritability that may present as “thumps,” a strong contraction of the muscular diaphragm that occurs with each beat of the heart.

Intestinal: Although the exact mechanisms are not clearly defined, dehydration and electrolyte abnormalities may put the horse at a higher risk of developing an exercise-related decrease in intestinal motility. This is a fairly common reason for endurance horses to be pulled from competition at vet checks.

Electrolyte Precautions
Endurance horses lose huge amounts of electrolytes in sweat during a race. It’s not surprising that supplementation of horses with concentrated electrolyte paste at frequent intervals is a common practice among endurance riders.

Researchers at Oklahoma State undertook a study to determine the effects of this on the horse’s stomach, particularly on gastric-ulcer score. There were 14 horses divided into two groups. One group received a placebo of 2 oz. of water every hour for 8 hours. The other got 2 oz. of concentrated electrolyte paste every hour for 8 hours.

The concentration of individual electrolytes per ounce was: 5,528 mg (5.528 grams) sodium, 11,886 mg (11.886 grams) chloride, 3,657 mg (3.657 grams) potassium, 754 mg calcium and 153 mg magnesium. Horses had their stomachs scoped before and after the eight-hour period.

There was a significant increase in both the number and severity of gastric ulcers in the horses receiving the concentrated electrolytes, so the authors concluded that frequent dosing of electrolytes could be harmful to the stomach. It should be mentioned, though, that exercise itself is a risk factor for gastric ulcers, so this schedule of dosing in a horse that is also exercising could pose an even greater risk.

You may minimize any potential harm from electrolyte supplementation by using one or more of the following modifications of dosing:

• Administer electrolytes in drinking water.

• Administer concentrated electrolytes immediately after the horse has a chance to drink, preferably a few gallons.

• Wait until after the horse has eaten to give electrolytes. When you must syringe-in the electrolytes, using a liquid antacid or corn oil as the carrier for electrolyte powders may help.

Finally, don’t count on signs of colic to alert you that your horse may have gastric ulcers. Nervousness, poor performance, poor eating and drinking during the ride—even poor recovery rates—may be nonspecific signs caused by ulcers.  Note: A 2004 University of California study scoped endurance horses at the end of either a 50 or 80 km race and found that 67% had gastric ulcers.

Put It To Use
• Horses need a minimum of 1 oz. salt daily; more in hot weather or when in hard work. • Even if you supplement electrolytes, be sure the horse consumes salt. • Make up for electrolyte losses during and after exercise.

Low Blood Potassium
A low blood-potassium level is a frequent electrolyte problem found in hard-working horses.  The usual response, understandably, is to supplement with potassium, but that often doesn’t work. Why? The reason is that many horses with chronically low-end potassium values are actually sodium/salt depleted. When making urine, the kidney secretes variable amounts of either sodium or potassium. Since the horse’s body is set up to conserve sodium in preference to potassium, if the body’s sodium levels are low, large amounts of potassium will be excreted in the urine.

Five pounds of hay supplies all the potassium a horse needs for maintenance. Potassium lost in sweat can be replaced with extra hay or a good electrolyte replacer. If low potassium continues to be a problem, your horse probably isn’t taking in enough plain salt. Try adding a minimum of 1 oz. of salt to his meals for a few days. If you use table salt, 2 tablespoons  = 1 oz. salt by weight.

Remember, when checking your horse’s electrolyte status, wait at least an hour after doing any work. Electrolyte shifts occur during exercise but reverse themselves once the horse stops working.