The docs at Duke University Medical Center have allowed a specially trained terrier named JJ into the operating room with his human handler, 7-year-old Kaelyn “KK” Krawczyk, ABC News reports. Why did they approve this? JJ reportedly has the ability to warn KK’s parents and doctors when the young girl is going to have a reaction due to a severe form of mastocytosis; a disorder that is caused by the presence of too many mast cells in her body.

“She gets too hot, she gets stressed, she has an infection,” KK’s mother Michelle Krawzyck explained ABC News. “Her reactions range from mild, like being flushed or irritable, to life-threatening drop in blood pressure, vomiting and difficulty breathing.”

JJ is able to detect the cell changes before KK has a reaction. Before JJ came along, KK needed all-night monitoring.

“We can sleep, which we didn’t do well before because we always worried she’d have a reaction she didn’t wake up from,” Krawczyk said, according to WTVD.

Eyes, Ears, Nose, and Paws, a nonprofit, trained the terrier to smell the scent KK emits before one of her episodes.

According to WTVD, when JJ stayed in the room with KK when the young girl underwent surgery on Wednesday, it was the first time Duke has approved the presence of an animal in an operating room.