(CBS) — They’re not just great companions.  Man’s best friend may also be a secret weapon in the fight against cancer.

As CBS 2′s Mary Kay Kleist reports, dogs are using their noses to help with early detection.

These dogs normally work in search and rescue, but now some of them are being trained to sniff out ovarian cancer.

“Ovarian cancer is the deadliest of the gynecologic cancers, and the reason for that is because it’s picked up as stage 3 or 4 disease, initially, in about 75 percent of women,” says Alexander Burnett, of the Division of Gynecological Oncology at University of Arkansas.

Currently, there is no effective early-screening tool for the disease. But Dr. Burnett hopes dogs can change that.  His study uses urine samples from women who have ovarian cancer and from women who don’t.

Donna Waugh is training five dogs to detect a specific scent associated with the cancer.

“They are very successful, highly successful in picking up cancer versus benign,” Burnett says.

He adds that one day the dogs may be able to detect cancer at stage 1 or 2, when it’s highly curable.

In California, dogs are being trained by Dina Zaphiris to sniff breath samples to see if they can pick out the cancerous ones.

“It’s a very specific, popping in and out of samples, and only rewarding them for the cancer.  And over time, they will ignore everything healthy, and only want to go to the cancer breath,” Zaphiris says.

Pat Smith,  a 14-year survivor of ovarian cancer, is very curious about the dog research.

She was lucky.  Unlike most patients, she had symptoms, including back pain and fatigue, that helped pick up the disease at just stage one.

“We have everything to gain and absolutely nothing to lose by using these dogs. I think it’s terrific,” Smith says.

The American Cancer Society’s most recent estimates for ovarian cancer in the United States are for 2012: About 22,280 women will receive a new diagnosis of ovarian cancer.

About 15,500 women will die from ovarian cancer.