Blood donors require screening to ensure good health and negative status for geographically relevant infectious diseases that could be transmitted via blood transfusion, including vector-borne diseases in dogs and cats as well as retroviruses in cats. Infectious disease screening guidelines are available for canine and feline blood donors.
Blood is collected aseptically into blood collection bags containing anticoagulant. Blood collected from a blood donor can be left as whole blood or split into packed RBCs, plasma, and platelet components. RBC products are stored at 2–6°C for 21–42 days. Plasma is considered “fresh frozen” when stored at −20°C for up to 1 year and considered “frozen” after 1 year.
When available, component therapy is used to replace only the components of blood required to decrease risk of transfusion reaction and optimize blood resources.
Packed RBCs are used to replace RBCs, especially in cases of hemolysis or lack of RBC production where plasma is not required. Whole blood is best suited for patients with blood loss.
Assessment for transfusion triggers or clinical signs of anemia, rather than reliance on a hematocrit cutoff value, is most helpful for deciding whether an RBC transfusion is needed. Clinical signs of weakness, tachycardia, tachypnea, hypotension, or elevated lactate concentration can indicate the need for RBC transfusion in anemic patients.
Hemoglobin-based oxygen carrier solutions (eg, bovine origin) are no longer available as RBC product substitutes. Similar products might be available in the future.
Plasma transfusion is indicated for hemorrhage secondary to coagulopathy and colloid support.
Fresh frozen plasma contains all coagulation factors, von Willebrand factor, albumin, antiproteases, and immunoglobulins; frozen plasma contains most of these components, aside from the labile coagulation factors V and VIII. Cryoprecipitate is a concentrated plasma source of fibrinogen, von Willebrand factor, factor VIII complex, factor XIII, and fibronectin.
Plasma transfusion is an inefficient method for replacing albumin in hypoalbuminemic patients. Commercially available lyophilized canine albumin is a concentrated albumin product suitable for treatment of hypovolemic shock and hypoalbuminemia. Transfusion of human serum albumin has been reported in dogs previously, although risk of severe hypersensitivity reactions now contraindicates use of this product.
Platelet-rich plasma and platelet concentrate can be made when whole blood products are processed into components; dimethyl sulfoxide-cryopreserved canine platelet concentrate is commercially available. Lyophilized canine platelets have been reported in the literature as useful for transfusion but are not commercially available.
Whole blood stored at room temperature for up to 8 hours is also a source of platelets, although it is a less concentrated source than platelet products. Platelets are thought to have a relatively short lifespan (up to a few days) after transfusion and are used for uncontrolled or life-threatening hemorrhage secondary to thrombocytopenia or thrombocytopathia, or as component therapy in massive transfusions.
