Date Adopted: April 10, 2018

Last date reviewed: January 15, 2021

I.  General Guidelines

A.  The acceptable quantity and frequency of blood sampling are determined by   
      the circulating blood volume and the red blood cell (RBC) turnover rate. Excessive
      blood collection may result in hypovolemic shock, physiological stress and even
      death. 

B.  For optimal health, blood draws should be limited to the lower end of the range.
     Maximum blood volumes should be taken only from healthy animals.

C. The approximate blood volume of a rat is 55-70 ml/kg of body weight. 
     Example: for a 300-g rat this is equivalent to 17-21 ml.

II.  Single Sample

A.  Without fluid replacement, the maximum blood volume which can be safely
      removed for a one-time sample is 10% of the total blood volume.
      Example: for a 300-g rat, this is equivalent to 1.7-2.1 ml.

B.  With fluid replacement, the maximum blood volume which can be safely removed
      for a one-time sample is 15% of the total blood volume.  Fluid replacement should
      be warmed and given subcutaneously.
      Example: for a 300-g rat this is equivalent to 2.5-3.2 ml.

III.  Multiple Samples

A.  If it is necessary to take multiple samples, smaller blood volumes are required. The
      maximum blood volume that can be drawn per week is no more than 7.5% of the
      total blood volume.
      Example: for a 300-g rat, this is equivalent to about 1.2 – 1.6 ml per week

B.  If sampling will occur every 2 weeks, up to 10% of the total blood volume may be
     drawn.  
     Example: for a 300-g rat, this is equivalent to about 1.7-2.1 ml every 2 weeks.
   
     Note:  For repeated blood collection, fluid replacement does not allow for a larger
     blood volume or more frequent blood collection.

IV.  Exsanguination

A.  Approximately half of the total blood volume can be collected at exsanguination.
     This is approximately 8-11 ml for a 300-gram rat.

B.  It is important to take into account the total blood volume yielded from the
     chosen blood collection technique when calculating the frequency and volume
     of blood collected. If you are not experienced in blood collection technique and
     would like training contact: Kelly.Carrick@mso.umt.edu

V.  Collection Sites