GIZA, Egypt — In a dank stable in the shadow of the Pyramids, a stallion lay on the ground, his broken leg at an odd angle despite the cast wrapped around it.

The owner, Farag Abu Ghoneim, hovered nearby as the animal was tended by an Australian nurse known here for her horse sense — and her passionate defense of suffering animals.

The stallion had been in pain for a week, after being kicked by a mare. “He’s not going to get any better,” said the nurse, Jill Barton, who came for the Great Pyramids of Giza in 2013 but stayed to help battered workhorses in Nazlet el-Samman, a ramshackle slum nearby. “You need to let him rest.”

Ms. Barton faces strong resistance from an impoverished community that has long seen horses and donkeys as working beasts, with little sentimentality about their pain.