Can dogs detect illness?

This is an article I found...

Q. I’ve heard dogs can smell when people are sick. Do they sense a change in a person or do they actually smell that something isn’t quite right?

A. A bit of both. Dogs have a remarkable sense of smell — bloodhounds have almost 50 times as many scent receptors as humans; that translates to a sense of smell that’s 10,000 to 100,000 times better than what we have.
Researchers in Germany followed a program developed at Dr. Mike’s Cleveland Clinic that trained dogs to detect the smell of a waste product of lung cancer. The German dogs can smell your breath and ID lung cancer correctly 93 percent of the time. A Japanese pooch sniffed the breath and stool samples of more than 300 people and correctly IDed which people had bowel cancer 98 percent of the time. Other studies demonstrate dogs can detect early stage breast cancer, melanomas and bladder cancer with an accuracy rate of 88 percent to 97 percent.
How is this possible? Malignant tumors exude tiny amounts of volatile organic compounds that aren’t in healthy tissue. Dogs can sniff out each one in concentrations as dilute as parts per trillion. The dogs’ ability to smell VOCs may lead to a new test to detect cancer. If it gets inexpensive enough, maybe we’ll all have a breath analysis once a year to spot early, otherwise undetectable, disease.
Dogs also can be trained to detect changes in behavior (when your tell isn’t your smell) and recognize the onset of high blood pressure, a heart attack and epileptic seizures, and to get a person the help he or she needs.

This is an article in the DM about dogs being able to sense a diabetic attack...

http://www.dailymail.co.uk/health/article-2147787/How-dog-smell-diabetic-attack-strikes.html?ito=feeds-newsxml