When should I give my horse electrolytes?


What started out as a simple answer (when he sweats) actually turns into something more complicated.  Can’t anything be simple with horses?   To get this explanation off to a rolling start, your horse needs his salt daily.  About a tablespoon of salt per 500 lbs. of horse.  I much prefer to measure this for him, as only then you can guarantee he’s getting his daily need of salt.  


Now, when he starts to sweat or is stressed, he will also sweat out some other things besides sodium.  Chloride, potassium, sodium, calcium, magnesium, and a few other trace minerals all need to be replenished in addition to your horse’s daily salt intake.  Horses have the amazing ability to sweat out loads of these electrolytes, leaving his body unbalanced.  Compare that to humans, whose sweat is basically water with a teeny tiny bit of electrolytes. 



But when to give electrolytes?  As a rule of thumb, give electrolytes to your horse before he needs them, within a four hour time window.   On hot days, if he’s trailering in the summer, when he will be sweaty from exercise or stress.  Be mindful of giving your horse electrolytes all the dang time, even when he doesn’t need them, as the calcium can interfere with your horse’s own mechanism to use his calcium reserves.  


If your horse gets a dose of electrolytes in the morning, then he doesn’t sweat, the ingredients are quickly and easily excreted in the urine.  If he does sweat, the electrolytes given will replace what he has lost.  


Now onto the dehydration part of the electrolyte question.  Many people give electrolytes to a dehydrated horse to stimulate him to drink.  The electrolytes in his GI system cause water to move from his blood to his gut.  When this happens, the salt concentrations in the blood rise and trigger the drinking desire.  BUT - some horses don’t drink in response to electrolytes, so the water that moves to your horse’s gut will actually dehydrate him more.  This is perhaps the key conundrum that will prompt you to feed electrolytes before anything might happen. 



It's very likely that I read horse labels a LOT more than I read my own food labels.  


How do you give electrolytes?  A sprinkle of them onto his morning meal usually does the trick.  Many horses won’t drink electrolytes in water (time to experiment!), and blocks are rough on a horse’s tongue so most horses won’t ever get enough to make a difference, and even then, it might be not be at a beneficial time. 


How do you pick the best type of electrolytes?  It’s part smart shopping, part horse taste test.  I look for ingredients that don’t have any words that end in -ose (like dextrose) as who needs the sugar.  Also avoid bicarbonate as an ingredient unless your horse has diarrhea and your Vet suggests it.  On a small tangent here, diarrhea can cause major issues beyond dehydration. Think colitis, organ failure, laminitis, and even causing other horses to be sick if a virus is the cause.  (For you tangent lovers out there, read this on manure!)


So - keep your eye on the weather, how much your horse sweats, and remember to give electrolytes first.