A rhino in South Africa that survived an attack by poachers who cut off her horns, leaving a massive wound on her face, has had a setback in her medical treatment.

A conservation group, Saving the Survivors, said Friday that veterinarians removed a protective mask from the rhino because she damaged it by rubbing her face against enclosure walls. The cast was placed on the 4-year-old rhino's face in a surgery on May 18 in Eastern Cape province.

Poachers darted the rhino with a tranquilizer and severed her horns while she was sedated. The rhino's rescuers named her Hope.

Veterinarian William Fowlds says Hope's face shield must be left off for now, despite concerns about infection, and that there are indications that the wound is healing.