Friday, July 3, 2015

PLOSOne study compares dog and owner oral bacteria using sequencing

Here's today's weird, but relevant, science paper which comes from a PLOS One study.  The authors asked whether dogs and their owners shared any oral microbiota. Thankfully the answer is "probably not":
The results of the present study suggest that bacterial dissemination between dogs and human is uncommon. ...Few bacteria from the canine oral microbiome were found in the owners’ oral samples. The number of [species] identified in both dogs and humans (4.9%, 12/246), was much lower than that in [a] previous study. Furthermore, among these shared [species], only four seemed to have disseminated from dogs to humans
That's great news, but the question that immediately came to mind was that this study needed to test more canine-owner pairs than just ten.  I trust this paper after learning the following today:
It is difficult for canine oral bacteria to survive and colonize the human oral environment because of the physiological differences between the two environments. First, dog saliva is less acidic (pH 8.5–8.65) than that of human saliva (pH 6.5–7.5). Because the oral microbiome is altered by pH, most bacteria in the dog oral cavity may not survive well in the human oral environment. 
Good to know, in case a dog actually kisses me.

Lastly, there's the tooth brushing argument:
Second, most humans brush their teeth every day (I assume this is true). During tooth brushing, most of the supra-gingival bacteria are removed and are then regenerated. Since dogs teeth are typically brushed less frequently than those of humans (I also assume this is true), they usually have a mature biofilm that is substantially different from the immature human oral microbiome. When canine oral bacteria are transmitted to the human oral cavity, they have to compete with human oral microbiome constituents and are removed by frequent tooth brushing.
I don't own a dog, but I'm now aware that a whole slew of dog dental care products exists on the market!