Left heart dimensions in anemic cats and dogs before and after blood transfusion

Whether anemic cats and dogs with increased left heart dimensions are at higher risk of transfusion-associated circulatory overload, and the effect of blood transfusion on left heart dimensions in naturally occurring anemia is unknown.

To evaluate the effect of blood transfusion on left heart dimensions in clinically relevant anemia.

Twenty dogs and 20 cats presenting to a university veterinary teaching hospital.

In this prospective observational study, anemic dogs and cats requiring blood transfusion were included. Packed cell volume (PCV), total solids, and echocardiography were performed before and within 24 hours of blood transfusion. Signalment, bodyweight, disease process, transfusion duration and volume, and prior treatments were recorded. Nonparametric statistics were reported as median [range]. Post hoc Bonferroni correction set significance at P < .006.

After transfusion, PCV increased in cats (12% [6-16] to 18% [10-33], P = .001) and dogs (14% [7-24] to 25% [9-37], P = .001), heart rate decreased in dogs (104 bpm [86-166] to 87 bpm [56-138], P < .001), and fractional shortening decreased in cats (57.1% [36.0-84.7] to 41.0% [28.1-69.6], P = .002) and dogs (33.79% [19.33-62.79] to 31.89% [19.06-51.47], P = .006). Left ventricular internal diameter in systole increased in cats (6.5 mm [2.7-9.8] to 7.9 mm [5.3-11.1], P = .001). Normalized left ventricular internal diameter in diastole (1.48 [1.25-1.79] to 1.57 [1.33-2.00], P = .001) and systole (0.87 [0.58-1.19] to 1.00 [0.74-1.36], P = .001) increased in dogs. Incidence of volume overload did not differ before (14/20 cats, 70%; 9/20 dogs, 45%) or after (12/20 cats, 60%; 11/20 dogs, 55%) transfusion (P = .64).

Blood transfusion is well tolerated when signs of volume overload are present before transfusion.