Replacing Electrolytes
Electrolyte losses in sweat cause dehydration, overheating, muscle problems, and poor intestinal tract movement. Replacing water is easy, but to keep it in the body, the electrolytes also have to be replaced.
Table I shows losses of the three major sweat electrolytes over an hour of work, compared to the horse's baseline need. As you can see, it's quite a lot. To fix this problem, you just start feeding a scoop of electrolytes, right? Wrong!
To figure out what your horse needs, you have to know what is already in his diet. Except for a small amount that may be added to commercial grains, there is basically no sodium in the diet. Sodium and chloride are what make up plain white table salt. An average-size horse needs 10 grams of sodium a day, not counting sweat losses. That amounts to just under an ounce (2 tablespoons) of table salt. Hay does contain chloride, although not quite enough to meet requirements. When you add in the chloride that comes from the plain salt, the horse will then have enough with even a bit left over. Potassium is plentiful in hay. Just five pounds of most hays will give the horse around twice as much potassium as is his baseline need.
Electrolyte supplements are meant to replace sweat losses, and good ones will provide close to the amounts listed in Table I in the low sweating column, per dose. However, as noted above, you don't need that potassium. There is a place for electrolyte supplements, but they have to be used correctly.
Checklist for Proper Use of Electrolytes
• Start by meeting your horse's baseline sodium and chloride needs with plain salt at 1 ounce/day in winter, 2 ounces/day in summer.
• If your horse is working two hours or less at low sweating rates, or one hour or less at moderate sweating rates, add 1 extra ounce of salt for each hour of low sweating work, 2 ounces for each hour of moderate sweating.
• If working longer than the times above, feed the extra salt only to meet the needs of the first two hours (or the one hour of moderate sweating), then use an electrolyte replacement for any additional work above that level.
Last but not least-and this is crucial while also being easy to do-give all horses as much water as they want, as often as they want it!
