what makes a blue hen mare?
Just that... what makes a blue hen mare? Are there "requirements"? Do their immediate offspring need to have reached a certain level of success, or must it be passed down through several generations in order to qualify?
For example: with the smashing debut by Ebloussaint (Zenyatta's li'l sis), as well as a couple other winning fillies, would their dam Vertigineux be considered a blue hen? Or would one of the mares need to also produce winning foals in order for Vertigineux be considered? Thanks to anyone who can satisfy my curiosity! :)