A Woman’s Dog Was the First to Detect Her Cancer

This pup saved her owner's life with her sense of smell.

It's no secret dogs are spectacular sniffers, but one pup has proven their sense of smell might be even more extraordinary than we thought. Sierra the Siberian Husky was able to detect the scent of her owner's cancer before healthcare providers were able to identify the disease.

Stephanie Herfel, of Wisconsin, had been dealing with abdominal pain when her new pup Sierra (pictured below) did something out of the ordinary.


Sierra Knew Something Was Wrong

"She put her nose on my lower belly and sniffed so intently that I thought I spilled something on my clothes. She did it a second and then a third time. After the third time, Sierra went and hid. I mean hid!" Herfel told the Milwaukee Journal Sentinel.

Herfel did see a doctor, but he dismissed what she was feeling as an ovarian cyst and gave her some pain medication to take the edge off.

Sierra, however, wasn't convinced. She tried to show Herfel that something more serious was going on by curling up in a ball and hiding in the back of the closet. And it turned out Sierra was right.

After Herfel made an appointment with a gynecologist, she was diagnosed with stage 3 ovarian cancer. She later underwent a full hysterectomy to remove her uterus and chemotherapy.

The Dog Detects Cancer Again and Again

Herfel finished treatment in April 2014, but just a year later, Sierra hid again. The cancer was back—and now it was in Herfel's liver. Then, in 2016, Sierra returned to her spot in the back of the closet. This time, the cancer was in Herfel's pelvic area.

Sierra had the same reaction when the Herfels had a friend over who also had ovarian cancer, and again when a new worker showed up one day during a kitchen remodeling job. They contacted the worker's boss, feeling obligated to let someone know.

Herfel is now cancer-free and plans to spread Sierra's story as much as possible. "I just feel like my story can let people think about their animals and think, 'Wow, my animal did this when I got diagnosed.' Just to give the animals credit that they are pretty smart," Herfel told the Journal Sentinel.


Dogs Trained To Detect Cancer

Sierra isn't the only dog who can smell illness. According to a 2021 review published in BMC Infectious Disease, dogs have highly sensitive smell receptors and their ability to detect odors far surpasses that of humans or electronic odor detection devices.

According to a 2022 research article published in Canine Medicine and Genetics, that powerful smelling system enables dogs to detect subtle odors given off by cancer cells called volatile organic compounds, even at extremely low concentrations in the air. The BMC Infectious Disease review explains that most dogs have to be trained to recognize these scents. But Sierra was clearly a special case.

Organizations like the UK-based group Medical Detection Dogs (MDD) train dogs to detect the odor of human disease in samples such as urine, breath, and skin swabs. MDD pups then participate in research studies to advance the understanding of how dogs can help with medical diagnoses.

One MDD dog, Lucy, has been able to detect cancer correctly more than 95% of the time, according to CNN. That's more accurate than some lab tests used for diagnosis.

A Quick Review

The research on how pups can be used in regular medical practice is still developing, but thanks to organizations like MDD, it's certainly advancing. Who knows, maybe someday we'll have dogs with special sniffers, like Sierra's, in hospitals everywhere.

Was this page helpful?
4 Sources
Health.com uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Milwaukee Journal Sentinel. Stingl: Dog sniffs out her owner's ovarian cancer three times, and she is right on the nose.

  2. Jendrny P, Twele F, Meller S, Osterhaus ADME, Schalke E, Volk HA. Canine olfactory detection and its relevance to medical detectionBMC Infect Dis. 2021;21(1):838. doi:10.1186/s12879-021-06523-8

  3. Azzouzi N, Guillory AS, Chaudieu G, Galibert F. Dog olfactory receptor gene expression profiling using samples derived from nasal epithelium brushingCanine Med Genet. 2022;9(1):7. doi:10.1186/s40575-022-00116-7

  4. CNN Health. Meet the dogs who can sniff out cancer better than some lab tests.

Related Articles