"La chica oye al perro" should be correct too. In fact, I'm pretty sure la nina implies little girl, not just a girl in general.
Earlier, I was given "Ella oye al perro." Why does "La nina oye al perro" not work
In fact, now it may have been changed as my "oye AL perro" was approved.
I got la nene oye el perro. Is nene another word for girl?
'Nene' is baby, or small child.