If the mare can not be used, an alternative donor that is Aa and Qa negative may be used. This donor profile is most commonly seen in Quarter Horses, Morgans, and Standardbreds and is less likely in Thoroughbreds and Arabians, but ideally the donor should be blood typed prior to use rather than using breed as the sole method of identification. In mule foals, female donors that have been previously bred to a jack should not be used.
In the event a mare cannot be utilized, an alternative donor with the Aa and Qa negative profile may be selected. This particular blood type combination is most commonly found in Quarter Horses, Morgans, and Standardbreds, although it is less likely to occur in Thoroughbreds and Arabians; ideally, the donor should be typed before use rather than relying solely on breed characteristics.