My only problem is that you keep saying pack. Honestly.... I think it's herd. Cause centaurs are very much like horses, so I think the terminology would move from real life to mythology. But! This is your art! Who am I to complain?
One little tid bit about horses not commonly known. In a herd of horses there is a female leader typically, serving as the matron of the herd. Some times a male has been seem acting as the matron. But most of the time the head of the herd is female.

Great art btw!