A Marine veteran is crediting the Siberian husky she inherited from her Air Force son in 2011 with helping to save her life after the dog sniffed out ovarian cancer three times. Stephanie Herfel, of Wisconsin, told the Journal Sentinel that it first happened in 2013 when the dog, named Sierra, began acting strangely around her.

“She put her nose on my lower belly and sniffed so intently that I thought I spilled something on my clothes,” Herfel, who had been experiencing abdominal pain, told the news outlet. “She did it a second and then a third time. After the third time, Sierra went and hid. I mean hid.”

With the dog cowering in the closet, Herfel made her way to the emergency room where she was diagnosed with an ovarian cyst, but Sierra’s strange behavior pushed the 52-year-old to make an appointment with her gynecologist. A few weeks later she was diagnosed with stage 3C ovarian cancer and underwent a full hysterectomy. She lost her spleen and continued with chemotherapy until April 2014, according to the Journal Sentinel.

According to the American Cancer Society, about 22,240 women will receive a new diagnosis of ovarian cancer this year, with it accounting for about 14,070 deaths. It's the fifth most deadly cancer in women, with women facing a 1 in 78 chance of developing ovarian cancer during her lifetime.

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In 2015, Sierra began acting strangely again, which Herfel later discovered was because her cancer had returned. It happened for the third time in 2016.

“Sierra smelled my cancer not only the first time by smelling my belly and hiding, but hid on my two reoccurrences where my scan showed an area of suspicion and I had to wait 3-4 months for another scan to confirm – she was right!” Herfel wrote in a Facebook post about gratitude on Nov. 28.

Herfel wrote in the Facebook post that Sierra even detected a friend’s tumor as well.

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On Sept. 25, Herfel posted that her latest scan was clear, and in November she marked 5 years of survival since being diagnosed with the disease. A previous post noted that she’s been enrolled in a clinical trial for 26 months, and it includes taking chemotherapy pills every day.

Herfel told the Journal Sentinel that she plans to write a book about her relationship with Sienna.