Is a cross-match necessary before a cat’s first blood transfusion?

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Appraisal, application and reflection

Traditionally, it has been advised that a cross-match has only been required prior to administering type specific blood to cats if they had a previous transfusion more than 4 days previously. Recently cross-match incompatibilities and transfusion reactions independent of the AB system have been reported. It has been hypothesised that naturally occurring alloantibodies to alternative red blood cell antigens are responsible, with particular interest paid to the Mik antigen, first reported by Weinstein in 2007.

Weltman et al. (2014) showed that administering cross-match compatible blood lead to greater haematocrit development when compared with non-crossmatched transfusions. Binangia et al. (2016), Hourani et al. (2017) and Sylvane et al. (2018) failed to repeat these findings in more recent studies, but did identify a reduced frequency of pyrexic (non-haemolytic) transfusion reactions in cross-matched cats. However, Weingart et al. (2007) reports two cases with an incompatible cross-match where transfusion did not increase PCV, suggesting treatment failure.

It is noteworthy that all reports of non-AB transfusion reactions in transfusion naïve cats originate in the United States, raising the possibility that a geographical element exists. In 2014, Tasker et al. were unable to demonstrate cross-match incompatibilities independent of the AB system in a cohort of cats from the United Kingdom.

A limitation of the papers reviewed were inconsistencies relating to the method of cross-match and whether only a major cross-match, or major and minor cross-matches were performed. In a major cross-match the donor’s erythrocytes are screened for incompatibility with the recipient’s plasma, whereas a minor cross-match tests for incompatibilities between donor plasma and recipient erythrocytes. Goy-Thollot et al. (2019) report an increased sensitivity of a feline antiglobulin-enhanced gel column method of cross-matching which was not used in any of the other studies. It is possible that such a technique is more sensitive that other techniques, however, the clinical significance of this is yet to be investigated.  

The application of these studies to clinical cases is still debatable. The only prospective randomised study (Sylvane et al., 2018) failed to show a difference in transfusion reactions between cross-matched and non-crossmatched cats and no difference in increase in haematocrit following transfusion. Based upon the studies presented here it is challenging to establish a meaningful clinical conclusion on which to base a recommendation.

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