I googled this question, Why are dogs’ noses always wet? (more or less), and was delighted to see that The Straight Dope had covered it! “At last, I will know,” I thought to myself…
According to SD veterinarian DrMat:
Dog noses are wet whether or not they’ve recently licked them. They aren’t wet from tongue saliva; my dog awakens wet-nosed. They have mucus glands on their surface, that keep them wet.
It takes about 5 minutes of observation to dispute DrMat’s theory.
Another link from my Google site tossed out two other theories, one of which makes sense to me:
The same link seems more interested in the theory that a damp nose helps regulate a dog’s body temperature; again, this is quickly debunked. Check a resting dog’s nose in the chill air of winter, and you will discover it is still damp. Ergo, it isn’t an effective means of lowering excess body temperature; we don’t turn the air conditioning on when it gets too cold inside. And why would it be? At most, a square inch of skin, on the wrong side of the nasal cavity for the constant in/out of breath, and that’s supposed to help cool my 55-lb dog? Nature builds better heat vents than that: the tongue (and, I suspect, blood flow on the bare belly, as a secondary process).
I’m buying the auxiliary scent-sniffing mechanism. After all, my dog goes nose-first into every wet clump of goo he finds. If he were actually sniffing, he’d get a nose full of muddy water half the time. But if his nose can smell merely by being dragged through the mess, then his actions make more sense.
Thoughts? I’d be happy to be proven wrong, if someone can overpower me with the awesome might of their arguments… but the report left me kinda “meh”, sadly.