Since she was two months old, Kaelyn "KK" Krawczyk has had a severe form of mastocytosis, which can cause a life-threatening allergic reaction to simple, everyday things - heat, exercise, even exposure to medicines.

Mastocytosis is a rare disease that causes an abnormal accumulation of mast cells in one or more organ systems. When mast cells are activated, they can induce immediate allergic inflammation. The disease is exceedingly rare and has a broad range of symptoms and severity, according to the Mastocytosis Society.

But for KK, a 7-year-old from Apex, N.C., these allergic reactions can be fatal and can escalate quickly to anaphylaxis or fatal shock.

"She gets too hot, she gets stressed, she has an infection," said her mother, Michelle Krawzyck, 39. "Her reactions range from mild, like being flushed or irritable, to life-threatening drop in blood pressure, vomiting and difficulty breathing."

Doctors had warned the family that KK might not even be able to go to school.

"They said it wasn't safe," said Krawzyck, who has four other children, ages 4 to 16. "She could go into anaphylaxis quickly and we would not know the trigger. We were devastated."

KK needs to be monitored all night long so her parents worry that anything, even hot blankets, might lead to a reaction that causes a fall down the stairs, unconsciousness or worse.

But for the last 18 months, they have a much better medical watchdog: a terrier named JJ who can smell the cell changes before she has a serious reaction and warn her parents that she needs her medical kit.

KK has recurring kidney infections and trips to the hospital. Doctors have discovered that the dye used in surgical procedures and the chemicals in anesthesia can trigger dangerous allergic responses.

"One of the things we know is that she is at high risk for anesthesia," said her mother. "She had a really bad reaction coming out of it in the past. She was really flushed and her blood pressure was low and she had shortness of breath."

So just this week, doctors allowed JJ and her trainer to accompany KK into the operating room at Duke University Medical Center, where she was to have exploratory kidney surgery. The dog was there to alert the anesthesiologist in advance of a reaction so they could ward it off with medication before it becomes life-threatening.

"It was kind of logical, actually," her anesthesiologist, Dr. Brad Taicher told the News-Observer, which first reported the story.

"Knowing what JJ could do, we realized that JJ was not much different from other monitors we use."

And JJ does her job well. The terrier picks up the scent of KK's cell changes, then barks and tugs at her parents' clothes.

"The other cool thing she does is she knows how to retrieve her kit with the life-saving meds."

Just one month into training in January, JJ responded during one of KK's worst reactions.

"She started licking our daughter to get her up," said Krawczyk. "All the cardiac monitors were in the normal range. KK said, 'Mommy, I feel like there's a ball in my throat.' She was having swelling, and time is of the essence. Four minutes after JJ alerted us, the monitors started to change."

"She alerts the hospital staff before all their fancy equipment can," said Krawczyk. "It makes believers out of those who didn't believe and confirmed those who did. JJ was a better indicator of when things are starting to go wrong than all the monitors."

JJ was trained in scent detection by Deb Cunningham, program director at Eyes Ears Nose and Paws in Chapel Hill, a nonprofit service dog agency.