Good news for dog lovers. Treating your dog like a member of the family doesn't seem to spread germs.

Many dog owners enjoy having their dog sleep in the same bed with them and having their face licked. Other dog owners (and many non-dog owners) won't permit such behaviors. A Kansas study compared the intestinal bacterium E. coli from each type of owner to those of their dog. About 10% of the human bacteria genetically matched those from the dog, no matter what type of behaviors the dog was permitted.

The idea behind this study may seem baffling to a dog lover, who would gladly allow a few face licks...

This was taken to mean that "free range" dogs were not spreading microorganisms to their owners. If they were, the more permissive owners would have had more matches. E. coli is a normal inhabitant of the intestinal tract of both humans and dogs; it was used as a general indicator of all microorganisms.

The idea behind this study may seem baffling to a dog lover, who would gladly allow a few face licks even if they did run the risk of a few extra days sick each year.

The study was undertaken because about 75% of emerging diseases are transferable between humans and animals. With the rise of antibiotic resistance (which can be transferred from one bacterium to another), the transfer of microorganisms between dogs and humans could be a potential public health issue. This study indicates no such problem.

The researchers did find more multiple antibiotic resistance in the E. coli than they expected to see — evidence that antibiotic resistance is on the rise. This is one reason that people should take antibiotics only when needed and finish the entire prescription. The study also found a link between antibiotic resistant E. coli and the frequency with which dog owners washed their hands after petting their dogs, particularly before activities like food preparation (which you should wash your hands before starting, whether or not you have a dog).

Kate Stenske, a clinical assistant professor at Kansas State University's College of Veterinary Medicine, became interested in performing this study because of the strong bond between most dog owners and their dogs. Surveys have shown that over half of all dog owners permit face licking, sharing their bed and sharing of food with their dogs. Over 84% of the people in one study said that their dog is like a child to them.

Previous studies have shown many physical and psychological benefits of having a pet. To animal lovers, this is a relationship that transcends numerical or scientific analysis. Likewise, there are those who don't care for pets at all. There seems to be very little middle ground. People either love their pets or strongly prefer life without them.

Stenske is interested in doing a similar study of cats. As she notes, cats interact with people differently than dogs do. For one thing, they're not interested in cooperating with the researchers.

The study was conducted by analyzing stool samples of dogs and their owners and matching the DNA fingerprints of the E. coli in the samples. An article on the study is due to be published in an upcoming issue of the American Journal of Veterinary Research.