Wikipedia
Xenotransfusion (from Greek xenos- strange or foreign), a form of xenotransplantation, was initially defined as the transfer of blood from one species into the veins of another. In most cases, it is a transfer of blood between a non-human animal and a human. However, further experimentation has been done between various non-human animal species. This procedure can be performed without affecting the health of the donor, as only about 10% of their blood volume is used each time. Utilizing the unlimited blood supply from animal sources eliminates the risk of transmitting infectious diseases between humans.
In 1658, Dom Robert des Gabets, a French monk, introduced the idea of xenotransfusion at a scientific society meeting. This society later afforded the French Academy of Sciences. Currently there are not any laws prohibiting the practice of xenotransfusion, but some ethical issues have been identified by the Ethics Committee of the International Xenotransplantation Association (IXA). For example, the IXA sets standards and regulations for those planning to orchestrate clinical xenotransplantation trials. The IXA has identified three major ethical areas that require adequate attention: favorable risk and benefit assessment supported by pre-clinical data, lack of alternative treatment for participants, and minimizing the risk of infection by ensuring the highest biosafety regulations are followed for selected animal donors. These are just a few examples of the ethics behind xenotransplantation.