Objectives: The most common use of plasma transfusion is for haemostatic purposes, but coagulation factor activities in stored feline plasma are unknown. The concentration and stability of coagulation factors I (fibrinogen), II, V, VII, VIII, IX, X, XI and XII in feline fresh frozen plasma (fFFP) stored for 1 year were studied.

Methods: Fifty-five units of fFFP were produced from 55 fresh whole-blood donations obtained from indoor healthy blood donor cats. Twenty-one units were stored for <2 weeks (T0) and 34 were stored for 1 year (T1). After the completion of storage, specific coagulation factor activities for factors II, V, VII, VIII, IX, X, XI and XII were tested using modified one-stage activated partial thromboplastin or prothrombin time assays. Fibrinogen was determined using the Clauss method.

Results: Significantly decreased activities were observed for factors II (T0: 101.94% ± 19.06%; T1: 73.23% ± 39.06% [P = 0.001]), VII (T0: 102.78% ± 24.69%; T1: 60.08% ± 38.17% [P <0.001]), VIII (T0: 77.52% ± 30.39%; T1: 50.32% ± 23.8% [P = 0.001]), XI (T0: 88.76% ± 22.73%; T1: 66.28% ± 22.2% [P = 0.001]) and XII (T0: 89.50% ± 21.85%; T1: 55.46% ± 23.18% [P <0.001]) when comparing units at time 0 and after 1 year of storage. No significant difference was observed for factors IX (T0: 84.86% ± 29.35%; T1: 71.37% ± 22.23% [P = 0.064]) and X (T0: 96.24% ± 25.1%; T1: 83.91% ± 49.54% [P = 0.236]). Unexpectedly, a significant increase was observed for factor V (T0: 71.94% ± 24.14%; T1: 97.89% ± 62.33%; P = 0.046). Fibrinogen was 2.76 ± 1.09 g/l at T1. Factors VIII, XII and VII had the lowest mean activities after 1 year.

Conclusions and relevance: Although a decrease in most coagulation factors activities was noted with storage, 1-year-old fFFP was haemostatically active in vitro. The most suitable factors for quality control assessment of fFFP are factors VII and VIII. Approximately 13-20 ml/kg of fFFP is required to administer a minimum of 10 IU/kg coagulation factor activity.