When a hidden cancer was silently growing inside Breanna Bortner, it wasn’t her doctors who first knew something was wrong.
In the days leading up to her dreaded diagnosis in June 2023, the 30-year-old noticed her dog, Mochi, acting strangely.
As Bortner waited for scans to come back on her right breast, the two-year-old cockapoo was suddenly fixated on the area.
He started sniffing and pawing at the Minnesota entrepreneur’s breast, burrowing his head into the area. Around the same time her sister-in-law’s cockapoo, Gunner, started doing the same thing.
‘It was very odd,’ she told DailyMail.com.
Bortner, who had heard stories of dogs sniffing out their owners’ cancers, instantly ‘knew this wasn’t good.’
Days later, she was diagnosed with stage 2B triple-negative invasive ductal carcinoma, an aggressive form of breast cancer that’s resistant to many common treatments.
Bortner, now 31, told DailyMail.com: ‘It was already and inch and a half big.’
Three months earlier, a routine breast exam had come back clear. ‘That’s how fast and aggressive this triple-negative breast cancer is,’ she added.
‘It went from non-feel-able, non-detectable to a physical lump within three months.’
Breanna Bortner, pictured here, was diagnosed at age 30 with stage 2B triple-negative invasive ductal carcinoma, an aggressive form of breast cancer that starts in the milk ducts
In the days leading up to Bortner’s diagnosis, her cockapoo Mochi (pictured here) started sniffing and burrowing his head into her breast, which had a 1.5-inch lump
Since Bortner’s diagnosis, she’s had more than a dozen brutal rounds of chemotherapy and a mastectomy.
While the survival rate for this form of cancer is nearly 100 percent in early stages, it drops to as low as 31 percent when it spreads to lymph nodes and surrounding organs.
Bortner was already undergoing testing at the time, but she said Mochi’s shift in behavior made her realize something was wrong.
It was the catalyst that helped her get diagnosed and start treatment immediately, possibly saving her life.
Bortner, who also runs the blog Brave Beautiful Boobies, said: ‘We really underestimate how smart [dogs] are just because they don’t talk and they can’t communicate to us, but their actions obviously show us the things that they’re tuning into or are aware of.’
Scientists estimate a dog’s sense of smell is anywhere from 10,000 to 100,000 times more powerful than a human’s, meaning some breeds can detect a substance at a concentration of just one-billionth of a teaspoon.
Mochi is as mix between a poodle and a cocker spaniel, two breeds originally bred for hunting due to their intelligence and keen sense of smell.
This supreme sense of smell has been used to detect anything from drugs and explosives to tracking the trial of a criminal.
Some breeds can even sniff out blood sugar changes in diabetics or sense an oncoming seizure in an owner with epilepsy.
In the case of cancer, malignant cells release tiny chemicals called volatile organic compounds (VOCs), which are thought to leave behind unique odor signatures.
Dogs with particularly keen senses of smell may be able to detect these odors in a person’s skin, breath, urine, feces, or sweat.
And because dogs’ smell is far superior to humans, research suggests they may be able to pick up on these odors when cancer is still ‘in situ,’ or has not spread from its primary site.
For about a year leading up to her diagnosis, Bortner noticed she had become increasingly fatigued.
In June 2023, three months after a breast exam had come up clear, she was itching mosquito bites around her breasts when she noticed a lump.
Mochi wasn’t the only dog who began acting strangely. Bortner’s sister-in-law’s cockapoo, pictured on the left alongside Mochi, also started sniffing around her breast
In the above image, Mochi helps comfort Bortner during cold capping, a procedure meant to prevent hair loss during chemotherapy treatments
She planned to get retested anyway, but when Mochi began sniffing her chest, it served as a wakeup call.
Bortner spent the next month driving to neighboring cities and shopping around for doctors who could get her in for further testing before she received the devastating diagnosis.
Invasive ductal carcinoma accounts for about 80 percent of all breast cancer. ‘Ductal’ means it forms in a woman’s milk ducts.
Bortner’s cancer was also triple-negative, meaning her breast cells didn’t have receptors that respond to the hormones estrogen and progesterone and the protein HER-2.
Without these receptors, triple-negative breast cancers don’t respond to treatments that target these hormones, making them harder to treat.
Bortner, pictured here cold capping with Mochi, told DailyMail.com: ‘He was there more than anyone else. He was my main guy’
Mochi has developed separation anxiety after spending countless hours helping Bortner cope with her treatments, though he is still a ‘pretty chill dog’
Triple-negative cancers account for about one in five breast cancer diagnoses.
Bortner had 16 rounds of chemotherapy and a year of immunotherapy treatment before undergoing a double mastectomy, a surgery to remove both breasts, in March 2024.
She was declared cancer-free shortly after and now has scans every three months to make sure the disease hasn’t returned.
Bortner said her and Mochi developed an inseparable bond during her treatment, spending countless hours on the couch snuggled up.
Especially as she struggled with the emotional side of cancer, Mochi stayed right next to her.
Even when Bortner’s husband would come home from work, Mochi preferred to spend time with her.
She said: ‘I was crying all the time and he did not like that. He was very concerned about me.
‘He really turned into my healing buddy. He was a greater purpose for me.’
Mochi stopped pawing at Bortner’s breasts after her treatment ended, though he developed separation anxiety once she started leaving the house more following her recovery.
She said: ‘He spent so much time with me here. That’s just kind of been the status quo. So now when I leave the house or he’s home alone, he’s been getting into the trash can and showing some behaviors that are quite new.’
Bortner said she is working with Mochi’s trainer to help alleviate some of his newfound anxiety.
Since beating cancer, Bortner is now focusing on running her online business and spreading awareness about breast cancer detection, especially in young women like her.
She said that while she was ‘lucky’ doctors took her concerns seriously and got her in for testing before the cancer spread, Mochi’s vigilance is likely part of why she’s still here today.
She told this website: ‘It’s pretty cool to see it come full circle and for him to be there from the time I found the lump all the way through finding out I was cancer free.
‘He was there more than anyone else. He was my main guy.’
Bortner is now cancer free after 16 rounds of chemo, one round of immunotherapy, and a double mastectomy. She credits Mochi for being with her every step of the way
Dina Zaphiris, director of the In Situ Foundation in California, has said almost any dog can be trained to detect cancer.
However, she generally picks German Shepherds, Labradors, poodles, and herding breeds because they have a strong work ethic.
One 2021 study from researchers in Germany tested if dogs could detect lung cancer from breath and urine samples.
After completing a one-year training program, the dog in the study correctly predicted 40 out of 41 lung cancer samples, a 98 percent success rate.
In a 2021 Japanese study, researchers trained a Labrador retriever to recognize VOCs from breast cancer patients by sniffing the patients’ urine samples.
In a double-blind experiment, the dog was able to correctly identify all 40 breast cancer patients with 100 percent accuracy.
A Labrador retriever in Japan was also able to detect more than nine in 10 cases of colon cancer based on breath and stool samples, even cancers that were in their earliest stages.
And in a 2019 study, three beagles underwent eight weeks of training and were then able to distinguish between blood serum samples of lung cancer patients and healthy controls with 97 percent accuracy.
Dogs have also been shown to detect cancer in other dogs.
A 2023 study from researchers at the University of Wisconsin and the University of Alabama, for example, suggested dogs may be able to detect cancer biomarkers in other dogs’ saliva.
The team collected 139 saliva samples from dogs with cancer and 161 samples from healthy dogs.
The six sniffer dogs in the study had ‘high sensitivity rate and high specificity rate in distinguishing between cancer samples and the healthy samples,’ according to a university press release.
However, many dogs, like Mochi, don’t need any special training.
If a dog detects cancer, they may not just sniff in that area, especially if they are not properly trained to do so.
In one BMJ case report, a 75-year-old man in the UK visited his doctor after noticing his dog was constantly licking behind his ear.
Tests confirmed he had melanoma, the deadliest form of skin cancer.
