Adopted: April 10, 2018

Last date reviewed: January 15, 2021

I.  General Guidelines

A.  The acceptable quantity and frequency of blood sampling is 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 mouse is 55-80 ml/kg of body weight (6-8% of
      their body weight).
      Example: for a 20-gram mouse this is equivalent to 1.1 – 1.6 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 20-gram mouse, this is equivalent to 0.11 – 0.16 ml (110-160 µl).

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.
      Example: for a 20-gram mouse this is equivalent to 0.16 – 0.24 ml (160-240 µl). 
      Fluid replacement should be warmed and given subcutaneously.

C.  Note: 0.1 ml = 100 µl = 2 drops of blood

III.  Multiple Sample

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 20-gram mouse, this is equivalent to about 0.08 – 0.12 ml per week
      (80-120 µl).

B.   If sampling will occur every 2 weeks, up to 10% of the total blood volume may be
      drawn.
      Example: for a 20-gram rat, this is equivalent to about 11 – 0.16 ml (110-160 µl)
      every 2 weeks.

NOTE:  For repeated blood collection, fluid replacement does not allow for a larger blood volume or more frequent blood collection. To maintain the optimal health and physiological stability of the mouse, blood volume withdrawn(whether repeatedly or only once) should be limited to the lower end of the suggested range.

IV.  Exsanguination

A.  Approximately half of the total blood volume can be collected at exsanguination.
      This is approximately 0.55 – 0.8 ml for a 20-gram mouse.

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