Blood Compatibility in Cats

In the Literature

Goy-Thollot I, Nectoux A, Guidetti M, et al. Detection of naturally occurring alloantibody by an in-clinic antiglobulin-enhanced and standard crossmatch gel column test in non-transfused domestic shorthair cats. J Vet Intern Med. 2019;33(2):588-595.

The Research …

Domestic cats have one major blood group system, the AB system, which consists  of types A, B, and AB. Most type A cats have no or weak naturally occurring anti-B  antibodies (ie, alloantibodies), all type B cats have strong anti-A alloantibodies, and type AB cats have no alloantibodies.¹ Typing for the presence of A and B antigens is recommended for blood transfusion recipients, blood donors, and mates before breeding to ensure an effective transfusion, reduce acute hemolytic transfusion reactions, and prevent neonatal isoerythrolysis in type B lactating queens with type A kittens.² In addition to the feline AB system, the Mik RBC antigen has been proposed to be an additional feline blood group system. Alloantibodies may exist in some Mik-negative cats,³ but no commercial tests  are available to blood type for this group.

In addition to typing for the presence of A and B antigens before a first transfusion, crossmatching is also recommended to detect the presence of allo-antibodies outside the AB system (eg, anti-Mik). Methods for identifying  naturally occurring antibodies in cats include slide (Figure 1), tube (Figure 2), gel (eg, antiglobulin-enhanced gel, column card gel; Figure 3), and immuno-chromatographic techniques.

FIGURE 1

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FIGURE 1

Slide crossmatching technique. An incompatible crossmatching result (left) with all RBCs agglutinated (ie, presence of alloantibodies) and a compatible crossmatching result (right) with no evident agglutination (ie, absence of alloantibodies)

FIGURE 1

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FIGURE 1

Slide crossmatching technique. An incompatible crossmatching result (left) with all RBCs agglutinated (ie, presence of alloantibodies) and a compatible crossmatching result (right) with no evident agglutination (ie, absence of alloantibodies)

This study detected naturally occurring antibodies via a new, in-practice, antiglobulin-enhanced gel tube crossmatching test and compared the results with a laboratory gel column card method to establish crossmatching recommendations in cats that have not previously received a transfusion. There  was good agreement between the 2 crossmatching test results, but the anti-globulin-enhanced crossmatching kit revealed additional incompatibilities outside the AB system. The associated RBC antigens and clinical importance of these and other alloantibodies remain to be determined.

… The Takeaways

Key pearls to put into practice:

• Type A cats have no or weak anti-B alloantibodies, whereas all type B cats have strong anti-A alloantibodies and type AB cats have no naturally occurring alloantibodies. However, naturally occurring antibodies could be found in some Mik-negative cats.

• Naturally occurring antibodies outside the AB blood group system can be identified by performing crossmatching, and an antiglobulin-enhanced gel tube crossmatching test can reveal incompatibilities not detected by usual methods (eg, column card gel technique).

• Based on this study and prior publications on alloantibodies, it is recommended that cats be crossmatched and typed for AB compatibility prior to their first transfusion.