Though dogs are affectionately known as man's bestfriend, experts caution that letting dogs lick people's faces could lead to the spreading of disease.

Professor John Oxford, emeritus professor of virology and bacteriology at Queen Mary, University of London, asserted that viruses could also be caught from dogs, whether from their saliva or fecal contact. "Dogs spend half of their life with their noses in nasty corners or hovering over dog droppings so their muzzles are full of bacteria, viruses and germs of all sorts," said Professor Oxford in The Hippocratic Post. "Some, but not all viruses, can cross the species barrier and these are the ones that may cause problems."

Most people wouldn't be able to resist letting excited puppies lick their hands and faces, but Dr. Joe Kinnarney, the immediate past president of the American Veterinary Medical Association, highly discourages this since a puppy could have as many as 20 million to 30 million roundworm eggs in its intestinal tract each week.

Dr. Leni K. Kaplan, a lecturer of community practice service at Cornell University's College of Veterinary Medicine, asserted that bacteria such as clostridium, E. coli, salmonella, and campylobacter, which can be found in dogs' mouths, cause severe gastrointestinal disease in humans. According to the Food Standards Agency, campylobacter is the most common cause of food poisoning in the United Kingdom, resulting in an average of 280,000 cases of upset stomachs each year.

But Dr. Kaplan is not entirely unbending on the subject of canine affection. "When dog saliva touches intact human skin, especially in a healthy person, it is extremely unlikely to cause any problems, as there will be very little absorption through the skin."