can dogs sniff out cancer? because everytime i come acros a dog on the streets he tries to sniff my balls, strangely enough one of my testiscles hurt and is bigger then the other one
Yes, they can but the dogs are actually trained to do it.
Can a dog do it on it's own? Possibly. If its a new smell it hasn't encountered, then it may be interested in a quick sniff. However, from what I know is that the dogs aren't smelling the cancer were it's located. They smell it through your breathe or urine in the case of prostate cancer.