The Truth About Dog Kisses

We’ve all heard the line “dog kisses are healing” at some point or another.  The truth is, as therapeutic as it is to have a dog by our side when we are sick or injured, a dog’s tongue is not a medical device.  Some people don’t like being licked, and some people love it; that’s personal preference.  A few years ago, a discovery was made at the University of Florida where they isolated a protein in the saliva of mice called nerve growth factor.  Following this discovery, they found that nerve growth factor (purified and isolated), when applied to wounds, resulted in faster healing times.  There were many conclusions drawn, but the most publicized was “dog kisses heal wounds”.

While I rarely get offended when my patients lick me during appointments, I will never advocate the use of dog saliva as a healing agent.  Firstly, if you were to base your argument on this study, you’d have to have pure isolated nerve growth factor from MOUSE saliva.  I’m not sure where you get that.  Secondly, there have been no studies that actually link dog, cat or human saliva (complete with all its non-nerve growth factor ingredients) to better wound healing.  Thirdly, dog saliva can be potentially pathogenic.   If you still need another great reason not to impregnate a wound with saliva: we live in a lovely world with readily available soap and water.

The dangers in dog saliva are abundant and variable.  They can range from parasites to bacteria to viruses .  If you cultured the saliva of a dog, you would be able to isolate many bacteria populations.  Some of these are pathogenic, some not.  In the case of a normal immune barrier (intact skin and a good immune system) these bacteria are unlikely to cause disease.  In the case of an open wound, or a person with a less competent immune system (the very young, the elderly, people on certain medical therapies), these bacteria can infect a wound.  Aside from the bacteria, it is possible for dogs to pass parasites, perhaps the most common being giardia (“beaver fever”) and roundworms.  Roundworms in particular can result in visceral migration throughout the body (this is one of the main reasons why we recommend internal parasite control programs aka dewormer).  It is highly unlikely for rabies to be present in a dog’s saliva if they are up to date on vaccination and haven’t been exposed to rabies, but licking open wounds is just as dangerous as a bite if a pet had rabies.  These problems are not common, but still possible. 

The best thing you can do to prevent any of these diseases from being transmitted is to wash your hands.  It is also a great idea to discuss your situation with your veterinarian to know what is best for your family.  In medical school, physicians study humans, but in veterinary school veterinarians study animals and public health, so they are the best to discuss this with.

So, as far as cleaning your wounds go, my advice would be the following: If you have a competent immune system, no access to fresh water or soap, and you can’t find a mouse, I suppose a dog kiss would be an OK last resort, but as soon as you get home, I’d wash with soap and water.

Dr. Heather James

P.S.  One of my favourite resources for finding out about common dangers to us from our pets is from Dr. Scott Weese and the University of Guelph.  You can access his website at www.wormsandgermsblog.com