Equis ISSN 2398-2977

Blood: cross-matching

Contributor(s): Robert Shull


  • Test for blood compatibility between donor and recipient horses.
  • Preferably test before any transfusion.
  • Essential for second and subsequent donations.
  • Major crossmatch = recipients serum against donor red cells.
  • Minor crossmatch = recipients red cells against donor serum.


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  • Samples from donor and recipient should be prepared in the same way but should be carefully labeled to avoid confusion.
    To prepare washed red cells
  • Place 5 ml of saline in a sterile centrifuge tube.
  • Place a glass rod into the clotted blood and transfer the rod carrying red cells to the saline to give a weak suspension of red blood cells.
  • Centrifuge suspension for 2-3 minutes.
  • Pour off supernatant.
  • Resuspend cells in 5 ml of clean saline.
  • Repeat centrifugation.
  • Repeat washing of red cells at least 5 times.
  • After the last wash resuspend cells in 1 or 2 drops of saline.
  • This provides the final suspension of washed red blood cells for the test.
    To prepare serum
  • Centrifuge clotted blood for 2-3 minutes or until serum is clear.
    Compatibility test
  • Clean 2 glass slides.
  • Place on white paper.
  • Label slides, one for donor serum, the other recipient serum.
  • Place 2 separate drops of the appropriate serum on each slide.
  • Add 1 drop of washed red cells to each drop of serum.
  • To the donor serum add 1 drop of donor cells (this acts as a control).
  • To the other drop of donor serum on that slide add one drop of recipient cells (this is the test).
  • Likewise to the recipient serum add one drop each of donor cells (test) and recipient serum (control).
  • Label carefully.
  • Agitate slide carefully to mix red cells evenly with the serum.
  • Incubate at room tempetaure for 10-15 minutes (cover with Petri dish to prevent evaporation).
  • Read.
  • Even sedimentation of red cells in all 4 spots, ie donor serum with donor and recipient cells and recipient serum with donor and recipient cells.This is a fully compatible crossmatch.
  • Even sedimentation except in donor serum with recipient cells which show uneven hemagglutination.This is an incompatible crossmatch.
  • Even sedimentation in control spots only. Hemoagglutination in both test spots.This is a totally incompatible crossmatch.

Further Reading


Refereed papers