Xenotransfusion (the transfusion of blood from another species) of canine blood to cats has been historically performed commonly and is still performed nowadays in some countries. Considering the current lack of commercial availability of haemoglobin-based oxygen carrier solution (Oxyglobin), there may be rare occasions when treating an anaemic cat when compatible feline blood cannot be obtained, and where a transfusion with canine blood may need to be considered as a life-saving procedure. This article reviews the published evidence about feline xenotransfusion with canine blood and the results that can be expected with this procedure. Published evidence in a limited number of cases (62 cats) indicates that cats do not appear to have naturally-occurring antibodies against canine red blood cell antigens: compatibility tests prior to the first transfusion did not demonstrate any evidence of agglutination or haemolysis of canine red cells in feline serum or plasma. No severe acute adverse reactions have been reported in cats receiving a single transfusion with canine whole blood. Anaemic cats receiving canine blood are reported to improve clinically within hours. However, antibodies against canine red blood cells are produced rapidly and can be detected within 4-7 days of the transfusion, leading to the destruction of the transfused canine red cells in a delayed haemolytic reaction. The average lifespan of the transfused canine red cells is less than 4 days. Any repeated transfusion with canine blood later than 4-6 days after the first transfusion causes anaphylaxis, which is frequently fatal.