(CBS) -- Dogs that can diagnose cancer? Believe it or not, it's happening.
As CBS 2's Roseanne Tellez reports, specially trained cancer sniffing dogs are saving lives.
When Chicago firefighter Jim O'Malley worked with Engine No. 84, he was diagnosed with cancer by a group of dogs.
"I'm like, 'This is crazy,'" he says.
Since 2013, O'Malley and hundreds of his fellow Chicago firefighters have breathed into masks as part of a study. The breath samples are tested by dogs trained to sniff out cancer. A raised paw means a sample is positive.
When O'Malley got his results, he couldn't believe. But then doctors agreed. He had colon cancer.
"It really took the wind out of my sail," he says.
Within a month, O'Malley had lifesaving surgery.
"A lot of people shake their head and say, 'No way. No way a dog can figure this out,'" he says.
But dogs are figuring it out. Of 700 Chicago firefighters screened in 2016, 18 were accurately identified as having cancer. Four tested positive for pre-cancer.
"I think the dogs are detecting perhaps a cocktail of odors," explains Glenn Ferguson, founder of CancerDogs.
He says whatever it is, the dogs catch it 95 percent of the time and often before traditional screenings.
The breath test costs about $20. But it's not yet available to the public. Ferguson says he will test another 20,000 firefighters this year because they have a higher cancer risk.
"Almost every guy that I came on with is dead from cancer. And you see them go. It's terrible," says Mike Butkus, chief steward for Union Local 2.
He says the dog test was a hard sell at first.
"I've had guys call me saying you shouldn't be offering this test -- it's nothing but voodoo."
Not to paramedic Joe Davilo, who's squamous cell skin cancer was detected and removed.
"For what it costs or what the benefits are. I say everybody should have it done. Because what's it going to hurt?"
The O'Malleys are thankful for every hug and every day they have with Jim.
"They saved my husband's life -- there's absolutely no doubt," his wife says of the cancer-sniffing dogs.
The dogs are trained using breath samples from untreated cancer patients. A positive result is sometimes confirmed by a blood test that costs several hundred dollars and is not covered by insurance. The breath test may be more widely available in the next five years.
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