In the US "blood agar" is usually prepared from Tryptic Soy Agar or Columbia Agar base with 5% Sheep blood. Rabbit or horse blood may be used for growth of NAD-requiring organisms, such as Haemophilus species, but the hemolytic patterns may be inconsistent with those on sheep blood. (Human blood is discouraged because of the increased possibility of exposure to human blood-borne pathogens such as HIV or hepatitis.)