PCV/dehydration

[terre <tobytrot@bigfoot.com>]

Don't know if this will contribute to the conversation at all, but for what it's worth:
I work in a hospital lab analyzing blood.  One year, one of our docs wanted to do some studies on some of the humans running our marathon.  he drew blood before, during, and after the race; he was expecting to see a rise in hematocrit as a measure of dehydration.  What happened, in fact, was that the Hct changed very little--I rather thought at the time that he may have drawn the post samples too early--he got 'em virtually as they crossed the line.  Perhaps fluid shifts intra/extracellular and vascular were still in progress?
The intersting thing (to me) was that the wbc increased 3 to 4-fold (from a mean of 7-8 to one one 25-35).  All granulocytes (neutophils)--ie the absolute Lymphocyte count remained pretty stable.  I considered this evidence of marrow stress (opinions?), perhaps due to the marrow attempting to produce more rbcs (in response to increased need for oxygen), but being much slower than with wbcs.  (Does that make sense?)  Anyway, question 1) since horses can do the splenic thingy to meet increased oxygen debt, how do you relate increased hct to dehydration without considering that factor?  Question 2) has anybody looked at the wbc picture with horses?  Is it similar? or does it not occur?  If it does happen, can anyone think of an application for the information?
There--THAT was a lot of help, wasn't it?



Terre
I was gratified to be able to answer promptly. I said I don't know.
Mark Twain