why you don't over-electrolyte

["Susan Evans Garlinghouse" <suendavid@worldnet.att.net>]

>From: Kristi
>Email: iluvdez@yahoo.com

>I need info from anyone out there (Susan, Heidi, Truman?) who can
>SCIENTIFICALLY explain why you shouldn't force electrolytes on a  horse to
>try and make him drink.  I participate on a competitive trail list serve,
and
>there are lots of "new" riders who rely on it for advice. Someone has
>just posted a reply that says you SHOULD give electrolytes to a
>horse to try to make him want to drink, (she believes that to trigger
thirst >response, the horse should have electrolytes added and then he'll
drink to >balance the ratio). I learned from ride camp (and in Dr. Loving's
book >maybe? can't remember) that that's not a good idea, but I need the
WHY'S >so I can reply.  Also, please tell me if I'm remembering my info
wrong! >Thanks

>Kristi


Kristi, I'll answer as best I can.  I happen to agree about not forcing
electrolytes on a horse, in MOST cases, and certainly never on a dehydrated
horse.  Electrolytes given to a horse that is NOT dehydrated are well
absorbed, but sometimes it's hard to recognize the fine line between a horse
that's dehydrated and one that isn't.  You can look at skin tenting,
capillary refill, mucous membranes, etc and while this will certainly help
identify the horse that is badly dehydrated, it's not an exact measure by
any means.

The reason why you have to be careful about 'lyting a dehydrated horse is
because electrolytes require water from/in the GI tract to be absorbed.  If
the animal is dehydrated, and insufficient water available in the gut, then
the electrolytes will essentially just sit there until sufficient water
becomes available for absorption (and it's not an all-or-nothing thing, so
degree of dehydration is a big factor).  The body tries to compensate and
deal with the problem as best it can, so it will scrounge up the necessary
water by moving it from plasma volume (in other words, the blood) and into
the gut so that electrolytes can then be absorbed back into the blood.  Sort
of a robbing-peter-to-pay-paul thing.  If you have a horse that is already
dehydrated, and perhaps on the edge of a metabolic crash, then it is very
possible that by removing yet more plasma volume (even temporarily) from
circulation, you can push the horse over the edge---which is totally
opposite from what you were trying to do by 'lyting him in the first place!

Your friend is correct that electrolytes will create a thirst response, but
it can sometimes be a day-late-and-a-dollar short.  The thirst response is
not actually caused by the 'lytes themselves---it's caused by a loss in
plasma volume (and thus blood pressure) which was essentially created or
exacerbated by the electrolytes as described above.  When plasma volume
drops, the kidneys release a particular cascade of hormones that do various
things to restore blood pressure and increase plasma volume and one of these
responses is the thirst response.  This is also the same mechanism when
blood pressure is lost due to blood loss, it's really pretty fascinating if
you're into endocrinology (which I happen to be, but not everyone is, so I
won't inflict the whole thing on you, and it's really not important anyway).

Anyway, by the time the kidneys and hormones get around to triggering a
thirst response, the horse drinks in reponse to that thirst, and water is
absorbed back into plasma volume...well, you will eventually restore the
lost plasma volume, but again, it may take awhile and if you have a horse on
the edge of being in trouble, it may not be quick enough.  So forcing
electrolytes to restore hydration is not a good strategy.

Now, on the other hand, if you wait until a horse has has a good drink, and
then electrolyte him, that's alot better---because the gut already contains
sufficient water for the 'lytes to be absorbed, so water does not have to be
moved from plasma volume into the gut.  But in *most* cases, 'lyting usually
isn't necessary except under extreme circumstances.  Sodium is one mineral
that animals will develop a near-immediate craving for when they need it,
unlike most other minerals.  So if a horse needs some electrolyte
replacement, then just offering them to him in 'lyted water or whatever will
usually be sufficient.

In some cases, horses will do better if they're syringed with a bit during
extreme heat, humidity and /or intensity of exercise, in addition to
offering 'lytes in their water, mash, etc.  This can really vary widely and
rather than rely on rules of thumb, it's best to experiment around a little
with your horse to see what works.  In all circumstances, wait until the
horse has had a drink and then syringe electrolytes in small, more frequents
amounts rather than one big bolus.  Underelectrolyting by syringe is better
during an endurance event than overelectrolyting---only because research by
Carlson has demonstrated that even the best-drinking horse during hot
conditions is incapable of totally replacing his fluid output during a
50-mile endurance ride, and so is experiencing some degree of dehydration.
Unless you're working closely with a vet, and/or know that your horse has
just had a big tank of water and is metabolically all "A's", you need to be
*very* careful and conservative about extra 'lyting.  Syringing is possible,
and works well for many riders---just do it with awareness of what's going
on in the horse's body and what the concerns are in what you're doing.

So if you have a horse that you know needs to drink, rather than
electrolyting him in an effort to make him drink, try a few other tricks
instead.  Ron Waltenspiel and his patented construction helmet will hold the
water right up to the horse's mouth and based on Ron's record, I'll bet it
works.  Try floating some hay or apple slices in his water, or try adding a
flavoring agent, like a few handfuls of beet pulp to make it more palatable.
While I don't like letting my horse play in water that he has to share,
sometimes taking a bucket off to one side and letting him goof around a
little will get him to finally settle down and slurp it up (I don't do this
during conditioning rides, but if my horse really needs to drink, I'll do
whatever it takes).  All these things, in addition to whatever existing
thirst response he has without electrolytes, will encourage him to drink.
If he doesn't, you're alot better off slowing down, using other methods of
cooling (like sponging) to minimize fluid loss, and encouraging eating
(especially a nice sloppy mash of beet pulp) until he does start to drink,
rather than using electrolytes to force the thirst response into overdrive.

Hope this helps. :-)

Susan Garlinghouse, MS
Equine Research Center
California State Polytechnic University



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