Re: Are dogs' mouths cleaner than humans'?

That's an interesting question, Holly, and as usual with 'MadSci' 
questions there is no simple answer - just a whole lot more questions !

First of all, what do you mean by 'clean' ?  Less soil, dust mites and 
yesterday's breakfast in there ?  Or do you mean 'more or less infecious' ?

An animal's mouth (including our own) is a strange environment - inside 
and yet outside the body.  It has about the same temperature as the inside 
of our body, and is nice and damp, so it is an ideal breeding ground for 
bacteria - and there are plenty in there, no matter how often you clean 
your (or your dog's) teeth.  As if the bacteria needed any encouragement, 
they are nevertheless rewarded with a coating of yummy food several times 
a day !  

So what differences might we see between a dog's and a person's mouth 
bacteria ?  I think they would be pretty similar, and any differences 
would depend on their diet.  A wild dog, such as a wolf, would probably 
eat a large meaty meal once every few days, and perhaps 'snack' on mice or 
carrion in between.  This sort of diet would leave relatively little in 
the way of harmful deposits on their teeth, and dog's teeth are mostly 
smoother and more widely spaced than our own, so there is less chance of 
food becoming trapped.  We, on the other hand (or our pet dogs, if we 
are 'kind' to them) eat rich, sugary food many times a day - so - surprise 
surprise, we get lots of problems with our teeth !  

In the bacteria stakes, I think wild dogs win hands down over our plaque-
coated teeth and festering gums.  That said, what probably kills many old 
wild animals is deterioration of their teeth.  Teeth don't last for ever 
(as you will find when you get to my age !) and when a wild animal's teeth 
become very worn or broken, severe infections can set in, preventing them 
from feeding properly.  Also, if a wild animal depends on a diet which 
does lead to build-up of plaque, this can become very thick and hard, 
causing serious problems.

I think dog's mouths probably are cleaner, depending on how you measure 
cleanliness.  True, they may eat dirtier things, but mouths are very 
efficient at self-cleaning.  This is not to say that kissing dogs is a 
good idea - it can cause stomach upsets - among people who have to watch ! 
As for drinking from the toilet - don't knock it.  Toilet water in the 
average US or Euro loo is a lot cleaner than what most of the world's 
population has to drink.