- All MWDs should be cross-matched if 72 hours have elapsed since its first transfusion or if any previous transfusion resulted in a transfusion reaction. Crossmatching is the process by which donor and recipient blood are assessed for compatibility and thus reduces the likelihood of a transfusion reaction.
- There are two types of cross-matching: Major and Minor.
  - Major Crossmatch: Recipient’s serum is mixed with a suspension of the donor’s red blood cells. A major crossmatch detects antibodies present in the recipient’s serum that will react to antigens present on the donor red blood cells.
  - Minor Crossmatch: Recipient’s red blood cells are mixed into the donor’s serum. A minor crossmatch detects antibodies present in the donor’s serum that will react to antigens present on the recipient’s red blood cells.
- Performing a cross-match is accomplished using either a/an:
  - Commercial cross-matching test kit:
    - RapidVet® provides a testing kit called the RapidVet®-H Companion Animal Crossmatch Test for both major and minor crossmatching. The procedure involved in this kit is very similar to traditional laboratory based crossmatching and personnel should refer to manufacturer’s directions for the proper employment of the test kit. The advantage in using the RapidVet® kits is that the gel-impregnated kits used to do the final assessment prevent artifact if naturally occurring red blood cell auto-agglutination is present.
  - In-house, field-expedient procedure described below in Table 12. Equipment required:
    - Small centrifuge
    - Image result for Ethylenediaminetetraacetic acid (EDTA)
    - EDTA-impregnated blood collection tubes (purple top)
    - Non-serum separator blood collection tubes (red top)