**11. Conclusion**

Vital part of veterinary emergency and critical care medicine is transfusion medicine. It is also therapy of some disease of patient. Blood and blood products can be obtained through the purchase of blood products or donors. Potentially fatal adverse transfusion reactions risk is higher in cats than in dogs. Also, adverse transfusion reactions are very important for large animals. By using known donors and screening assays that permit detection of incompatibility of blood typing or crossmatching, the risk can be decreased in both species.
