During the original 70s run of Equus, they were looking for ways to keep it going.
Irene Worth approached both the producer's office (I think Bloomgarden was dead by this point) and Peter Shaffer citing the veiled attraction that the doctor develops for the boy, and might they consider that the doctor could be played by a woman with very little changes in the script? Funny how Irene had the perfect actress in mind.
Shaffer agreed with Irene's logic and was intrigued and didn't rule this idea out, but then Perkins extended and they decided not to go with it.
Point being, the doctor does develop an attraction to the boy and that is part of his conflict.
I heard this at a party while it was happening and I liked the idea because I knew Irene having worked backstage at Sweet Bird, and I knew she could bring it off.
[Sidebar: Irene Worth was 'that great English actress who was born in Nebraska and raised in California.' Sort of Vera Charles, but for real.]
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher