RH negative blood is rare and inventory is low (OTTAWA) – Preparations for Canada Day are underway and Canadian Blood Services wants people to think of blood donation as a gift to their country. We need all blood donors to book an appointment now, particularly those with Rh negative blood. “Only about 15 percent of Canadians are negative for the Rh antigen, which means that there is an absence of a particular protein on the surface of their red blood cells,” says Dr. Tanya Petraszko, associate medical director at Canadian Blood Services. “Blood from donors who are negative for the Rh antigen