A dog's sense of smell is so strong it can tell whether people have had sex.

Bizarre on Female First

Bizarre on Female First

A new book on canine behaviour says canines can tell whether we've had sex, exercised, smoked or eaten just by sniffing us.

Dog cognition expert Alexandra Horowitz, who has just released 'Our Dogs, Ourselves', suggests that we need to allow our pooches to have a good sniff around.

Alexandra said: ''We're not particularly interested in smells and think smelling people is rude.

''Because we want our dogs to reflect us we pull them away when they are right up in another dogs genitals or sniffing around the faces, ears or eyes of other dogs.''