The reason why dogs get wet noses is a fascinating subject and you’ll notice some breeds, typically search and rescue type breeds will lick their noses before and during scent work.
This is because a wet nose increases their sense of smell due to particles in the air sticking to the nose, this is another reason why the likes of basset hounds and spaniels have big ears, as they sniff their ears sweep the ground releasing a plethora of scents into their nostrils.
Have you ever noticed as you're prepping your dog's food and they lie in wait, they lick their nose and stick it into the air? This is so they can try and find out what’s on the menu no doubt, if they like the smell you’ll see the drooling especially in those droopy muzzle mastiff breeds!
You may even notice your dog's nose changing colour throughout the year and this is said to be totally normal, when a dog’s nose goes pink, it's referred to as “winter nose” by many so don’t panic!
Occasionally you’ll notice dogs with a dry nose, this commonly as a result of being in warmer climates/ hogging a heat source ( you know those crazy dog’s that insist on sleeping less than a foot away from an open fire or against a radiator)
A persistent dry nose in combination with heat seeking could indicate a thyroid issue as they’re struggling to regulate their core temperatures, if you’re ever concerned about this please get in touch with your vet and ask them to test the thyroid, specifically test the serum for T4 Vs Free T4.