Humans love dogs, but petting them can leave some people sneezing and wheezing. About 15% of the world's population lives with a dog allergy, which can increase the risk of hay fever and asthma. The main culprit is Can f 1, a protein found mainly in dog saliva. Right now, staying away from furry fri ends or getting regular immunotherapy shots or tablets is the only way to deal with the symptoms. ...read more read less