Black Lab Outperforms Lab Test at Detecting Cancer

Feb. 1, 2011— -- With a little training, a dog can learn to heel. But a new study adds to growing evidence that man's best friend can also learn to heal by detecting invisible signs of disease.

Marine, a specially-trained 8-year-old black Labrador retriever, detected colorectal cancer 91 percent of the time when sniffing patients' breath and 97 percent of the time when sniffing stool, according to a study published Jan. 31 in the British journal Gut.

She even beat the fecal occult blood test, the most economic and non-invasive screening for colorectal cancer, which positively predicts the presence of cancer only 10 percent of the time, according to lead author Dr. Hideto Sonoda, from Fukuoka Dental College Hospital in Japan, and colleagues.

This is not the first time dogs have successfully sniffed out malignancies. The phenomenon has already been reported in skin, bladder, lung, breast and ovarian cancers.

"We shouldn't be shocked by this," said Dr. Marty Becker, a veterinarian at the North Idaho Animal Hospital and author of "The Healing Power of Pets." "We know dogs can detect accelerants, explosives, mold, peanuts -- even counterfeit CDs."

It's estimated that a dog's sense of smell is up to 1 million times better than that of a human, depending on the breed.

"It's like having an NFL stadium filled with yellow balls and one red ball," Becker said. "That's the concentration of scent a trained dog could find."

But Becker cautioned that not all dogs are so gifted.

"You don't see bomb-sniffing pugs," Becker said. "You've got to have pretty robust olfactory capabilities."

Dogs have even been trained to smell chemicals signaling seizures in epileptics and elevated blood sugar levels in diabetics, according to Rebecca Johnson, associate professor at the University of Missouri's College of Veterinary Medicine and Sinclair School of Nursing, and director of the Research Center for Human-Animal Interactions.

In August 2010, a terrier named Kiko bit off his owner's big toe while he was passed out drunk, alerting the 48-year-old to his undiagnosed type 2 diabetes.