Researchers in Germany are a step closer to developing a new test for lung cancer … thanks to man’s best friend.

Lung cancer is the deadliest form of cancer in the U.S. Catching it early is supremely important, but that’s pretty tough to do. The disease doesn’t cause symptoms until it’s advanced. Existing diagnostic tools aren’t totally reliable, and past attempts to find better ones have been unsuccessful.

Previous research has explored the possibility of detecting lung cancer in patients’ breath. But scientists have been uncertain whether the disease actually causes changes in a person’s breath.

That’s where the dogs came in handy. Researchers writing in the European Respiratory Journal used a reward system to train dogs to distinguish lung cancer patients’ breath samples from those given by others. Then, the canines sniffed samples collected from 220 study participants and held in tubes. Some subjects had lung cancer, while others didn’t.

When a dog smelled a sample from a lung cancer patient, she lay down with her snout touching the mouth of the tube. Together, the dogs identified 71 percent of the samples from cancer patients. They weren’t confused by food odors or cigarette smoke in the samples, as some “electronic nose” devices are.

The study authors point to the animals’ work as proof that lung cancer emits some specific substance into a person’s breath. Otherwise, dogs could not possibly identify breath samples from people who had the disease.

But don’t expect canine-conducted breath tests to become part of your routine physical. The study authors say more work needs to be done to identify the substance the dogs recognized in the breath samples. Then, scientists will have to develop a device sensitive enough to detect it.

Too bad they can’t train a dog to design one for them.