TBV total blood volume

Originally Posted by docicu3

Total Blood Volume is a test for humans used to assess RBC mass from Serum
or put another way the number or mass of red cells relative to the fluid in the blood that is not Red Cell related.

It has recently been used for inpatients to make a noninvasive diagnosis (without floating a catheter in the blood vessel) of Congestive Heart Failure or when fluid is building up in the lungs. That is the simplistic answer as there is a ton of science here to assume with the measurement.

One way to use it with Epo would be looking at hemoglobin or Hematocrit measurements as a way of detecting excessive Red Cells that may be brought on by Epo use with Iron. Very Shaky science at best!!!

Opinion of mine in next sentence: After you reach a certain red cell number say a hemoglobin of 10 grams that more hemoglobin or a higher number does not translate into ability to run faster or longer.

I can say some things from personal experience
but I dont know how it translates to horses.

People with good endurance can have an unexpected
low hematocrit. It happens because they have a high
blood volume specifically the serum, not RBC's which are also
high, but get diluted by the liquid. The high blood volume
is probably from extensive capillary volume associated with
a very good mechanism for getting blood to and from muscles.
In other words, your muscles are so loaded with capillaries, your
blood volume is high. There is more tubing to hold more blood.

I had this happen to me when I was in very good shape from
running. The doc's were scared at first, but I went to a Doc
who was a runner and he said he had seen it before. Then
I find out about half the people I run with that are really in shape
have got the same readings; Low hematocrit, because the liquid
portion of the blood is so high, even though they actually have
more RBC's than they would out of shape with a normal hematocrit.

So it MAY point to horses that have a more extensive circulatory
system. This is all conjucture.
I agree with the poster about EPO being a big unknown.
In fact I can see it being a hindrance(my opinion based
on a number of factors)