The fact that dogs can sniff out cancer is pretty miraculous, but that’s not the only disease canines know how to catch with their incredible olfactory abilities. Medical detection dogs -- who have been trained to sense the symptoms of a range of illnesses -- perform a unique service unlike the typical assistance dog, alerting their owners to physical problems that might otherwise go unnoticed. Thanks to the work of Claire Guest, a doctor who founded the UK-based charity Medical Detection Dogs, dozens of lives have been saved (and improved) because of disease-sniffing dogs.

"I had a belief, a vision I suppose, that there were probably other medical conditions that dogs may be able to train to assist with and therefore become assistance dogs,” Guest told the BBC. She was right: of the 50 medical detection dogs her organization has provided, most are trained to help diabetes patients keep track of their blood sugar by smelling low glucose levels on their breath. Others are trained to assist with other disorders, like the rarer Addison’s disease.

Karen Ruddlesden, who suffers from Addison’s and cannot naturally produce the integral hormone cortisol, told the BBC that her dog, Coco, has helped her stay healthy and regain her quality of life. When Ruddlesden had to undergo a routine procedure, her dog was by her side at the hospital -- in part because her doctor requested that Coco come along. "They did the procedure and then wheeled me out to where Coco was," Ruddlesden said. "He put his feet on the trolley where he sniffed me, then looked at my partner who told the staff I was OK … Standard cortisol tests can take up to an hour, whereas Coco is instant."

Even Guest has benefitted from the help of a medical detection dog, despite having never been diagnosed with a chronic condition. While watching over Daisy, a dog trained to detect multiple different types of cancer, Guest learned she had breast cancer -- all because of her canine assistant. “She bumped into me and I felt a sore area, like a bruised area," Guest said. "Without question my prognosis would've been very different had Daisy not warned me.”

Now, Guest hopes to use her medical detection dogs to sniff out diseases that often get overlooked in the field of assistance animals, like pancreatic cancer. "There have been hundreds and hundreds and millions of pounds spent on cancer detection by big institutes and there has been no headway whatsoever made on the diagnosis of pancreatic cancer," she said. "I reckon a dog could detect that on breath samples."

Photos via Medical Detection Dogs.