A former grant writer credits her dog for saving her life after the pooch sniffed out her cancer three times.
Stephanie Herfel, 52, had been experiencing severe discomfort in her abdomen, which her doctor dismissed as a cyst.
Sent home with painkillers, Mrs Herfel made an appointment to see a gynaecologist when her Siberian Husky Sierra sniffed at her lower abdomen before running away and curling up in the wardrobe.
Mrs Herfel was diagnosed with stage three ovarian cancer just weeks later on November 11, 2013.
After undergoing a full hysterectomy, chemotherapy and having her spleen removed, Mrs Herfel thought she was disease-free until Sierra sniffed at her again in 2015 and 2016 - tests later revealed her cancer had returned both times.
Now free of the disease, Mrs Herfel believes she would not be here if it was not for Sierra. 'I owe my life to that dog,' she said. 'She's really been a godsend to me.'
Ovarian cancer affects around 22,200 new women every year in the US, with one in 78 women developing the disease at some point in their lives, according to the American Cancer Society.
Around 70 per cent of women with ovarian cancer see their disease return, which becomes more likely the more advanced it is when diagnosed, the Ovarian Cancer Research Alliance states.
In the UK, ovarian cancer affects around 7,200 new women every year. The chance of surviving more than a decade post-diagnosis is 35 per cent in England and Wales.
Sierra first sniffed at Mrs Herfel's abdomen shortly after they moved to Wisconsin from California. She adopted the pet from her son in 2011 when he left for overseas duty while serving in the airforce.
'Spooked out', Mrs Herfel, who served in the US Marine Corps from 1984 to 1988, contacted her gynaecologist. The doctor then arranged for her to have blood tests and an ultrasound scan.
After being diagnosed, Mrs Herfel thought she had undergone her final chemotherapy session in April 2014.
But in 2015 and 2016, Sierra correctly identified that the cancer had returned, with tests later showing the disease had spread to Mrs Herfel's liver and pelvis.
Her primary cancer doctor David Kushner told Mrs Herfel this was not a fluke, with some dog breeds being able to detect cancer with 98 per cent accuracy.