Otto's work builds on a 2010 Swedish study by Gyorgy Horvath, who used his own pet giant schnauzers to detect ovarian cancer. Tissue tests showed sensitivity of 100 percent and specificity of 95 percent; blood tests showed sensitivity of 100 percent and specificity of 98 percent.
Dogs with long noses -- hunting dogs like Labradors, golden retrievers and springer spaniels -- have the largest surface areas of olfactory receptors.
The first step is to get the dogs to recognize the odor in blood and then to move to a less-invasive test like urine or saliva. However, those types of samples won't have the same concentration of the odor, so it will be more challenging for the dogs and machines alike.
All dogs at the center are donated by breeders and go home each night to foster families. Some of the dogs will be part of the ovarian research and others, depending on their skills, will go on to military, law enforcement or service work.
Socks, Penn Vet's star golden lab, has just been assigned to the Pennsylvania Police Department to detect bombs.
"We look not only by breed, but how a dog is bred," said Otto. "They come from generations of hunting and working dogs selected for their ability to smell things."
According to one of the oncology collaborators, Dr. Janos L. Tanyi, a surgeon, cancer cells emit volatile organic compounds that have a distinct "signature" in the earliest stages of the disease, when cells are dividing.
"We believe that we can catch them when they are changing," he said.
Tanyi has asked 40 of his patients with the most common form of ovarian tumors to donate tissue from their surgeries. Most have advanced cancer.
"Between the surgery and the chemo, it's an exhausting and difficult time mentally and physically," he said of his patients. "They like it because it's fascinating and sounds like a bit of sunshine at a very cloudy time. They are really open for collaboration. ... They really want to help other patients."
Only about 10 to 15 percent of all ovarian cancer patients are diagnosed in the early stages when it is curable, because the symptoms are so "obscure," according to Tanyi.
Such was the case with Marta Drexler of Landsdowne, Pa., who had had a clean gynecologic exam just eight months before her diagnosis with advanced stage 3 ovarian cancer.
"This can happen, even if you are vigilant," said Drexler, 57.
She enthusiastically donated tissue samples from both her surgeries: "When Dr. Tanyi called, it was like the universe talking. ... It's a horrible disease."
Drexler worked for 20 years as a veterinary nurse and understands the powerful connection between humans and animals.
"I know their potential -- they are capable of so much," she said. "What I am excited about is all the women who will have a benefit from this in the future."
"Getting early detection -- that's what this is about," said Drexler. "It's a really simple idea. Dogs want to please us and do something for us."
Meanwhile, Otto said she feels an obligation to give back equally to her dogs. With a grant from the American Kennel Association, she has been able to continue monitoring the health of the 9/11 dogs for whom the research ones are named.
Unlike many of the humans who were exposed to toxins at Ground Zero, all six or seven of her surviving dogs, all retired, have remained healthy.
"Dogs are so important to our physical and mental well-being," said Otto. "Through my involvement with military working dogs and police and service dogs, there are so many aspects where dogs can make a difference for humans."
"I am surrounded by pictures of these dogs," she said. "I feel like it has opened some doors and I can make a difference in the world because of it."