Not unlike the “mud hen,” the Blue Hen is a breed of American gamecock, and can be of either sex.
YoUDee, the Delaware Blue Hens’ costumed mascot, is “officially androgynous.”
University of Texas Longhorns, though Bevo (the official, flesh-and-blood mascot) is a steer.
Williams College has the Purple Cow named Ephelia as their mascot for all teams.
And of course, banana slugs are hermaphrodidic.
You were close in two directions with this one. Geographically, Texas A&M’s mascot Revelle is a female collie and is known as the first Lady of A&M. Then you were close by being in the same family as Ralphie the Buffalo who is currently female.
The Wiki entry does say that a female English bulldog filled in for Uga in the 1971 season.
On the other hand, Georgia’s other, human, mascot, Hairy Dawg, is unquestionably male:
Just to be sure, which of the three is he?
The blonde.
(I should have said, Hairy Dawg is unquestionably presented as male.)
Some years ago I was in Toronto for a meeting and I went to a Jays game. I don’t recall if there was a male mascot, but there was Lady Jay, a female. She also sang the anthems and did a damn good job of singing them straight with no styling (I detest that). Then I got on a trolley to go back to my hotel (which was down the street from the Maple Leaf Gardens) and I saw Lady Jay get on the trolley. I went up to her to tell her how much I liked her singing and we had a bit of a conversation. She was interesting and intelligent and I enjoyed that.
The Charlotte Hornets mascot probably has a stinger, which would make it a female. Nobody is afraid of male hornets.
She definitely does.