Rigorous studies have long been done on dogs to determine just how sensitive their sense of smell is. Many results indicate it is such a strong sense for dogs that they are able to detect various kinds of cancer to a high level of accuracy, including early stages of lung and breast cancer by nothing more than smelling a patient’s breath.

Such was the case for a man near Oxford, England. His dog tried to sniff and get at a mole on the man’s chest – a mole he had for over 15 years. Eventually, he went to the hospital and after his skin biopsy and two weeks of waiting, he received word he had melanoma, the most dangerous form of skin cancer. He got the mole removed soon after and has not encountered any problems – thanks to his dog, he says.

source: www.medicalnewstoday.com/articles/130393.php