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Re: [RC] Education/Prevention - Heidi Smith

With aerobic work, there really isn't much lactic acid production to speak of.  Lactic acid is a byproduct of anaerobic metabolism.  Horses conditioned to do distance that have an abundance of slow-twitch muscle fibers just don't get acidotic working at the speeds that our horses work.  So virtually all shifts in the endurance horse are toward an alkalotic state.  So in the healthy endurance horse, the alkalotic shift isn't as severe as you may be thinking--it is simply more alkalotic than normal, rather than having to "overcome" any acidosis.
 
And yes, horses lose A LOT of chloride in sweat--but how much of a deficit this causes is also relative to how much of a forage fill they have in the hindgut, which serves as a reservoir for electrolytes and fluids to some degree--an adaptation that humans don't have.  (Nor do humans have the VFA production in a hindgut for energy, the way horses do--horses really are the consumate endurance animals!)  But loss of chloride and other e-lytes is of course why electrolyte supplementation is such a hot topic for our horses as well.
 
As to references for reading--I don't know of any specific texts on the subject, but perhaps Susan G can weigh in here with some good papers to which to refer you.  She's much better at scrounging through the literature than I am, and much of the stuff I've got in my files is older work.
 
Heidi
 
 
----- Original Message -----
Sent: Sunday, February 16, 2003 7:18 PM
Subject: Re: [RC] Education/Prevention

Sorry Heidi, my question (previous reply)  wasn't quite thought out enough.  Did you mean that a horse looses sufficient chloride in sweat to override lactic acid production from muscle exertion & hypovolemia?  WOW
 
----- Original Message -----
Sent: Sunday, February 16, 2003 7:54 PM
Subject: Re: [RC] Education/Prevention

>     It amazes me that even among some experienced riders there isn't a clear understanding that metabolic acidosis and electrolyte imbalance can lead to sudden cardiac death and that it takes more than IV fluids to get passed that possibility.
 
Endurance horses are alkalotic, rather than acidotic.  Metabolic alkalosis is particularly an issue, given the losses of chlorides, but respiratory alkalosis can be an issue in some as well.  But even so, you are right that simply putting the horses on IV fluids often isn't the whole story.
 
Heidi

Replies
[RC] Education/Prevention, Wendy Mancini
Re: [RC] Education/Prevention, Heidi Smith
Re: [RC] Education/Prevention, Wendy Mancini