The rest of their skin isn’t; what’s up with that?
Not all of them do. Plenty of dogs have brown noses.
I’ve also seen pink noses quite a lot, and bluish/silver-grey.
Anyhow, here is one answer. Basically, the presence of melanin causes the dark color and protection from the sun seems to be the guess for the reason the nose would have melanin.
We have 2 wiener dog puppies from a black-and-tan momma. One looks just like mom, the other is white with light brown markings. Looks like a nougat bar (hence his name, “Ted Nougat”). He’s got a pink nose and whitish claws.
He coat is noticeably softer than his sister and mom, also.
Whoooose a gooood boy? Who’s a good boy? Teddy! Teddy! Ted Nougat!
Many Huskies’ noses turn pink in the center during winter months. It is called “snow nose.” It changes back to black during spring and summer.
And our Australian Shepherd’s nose is always pink.
That’s because they go around sniffing each others’ butts.
A genetic explanation:
http://www.doggenetics.co.uk/liver.html
The tissue is similar to the pads of the feet, also hairless and pigmented, as a protective adaptation. Melanin is also deposited anywhere the skin is exposed to chronic inflammation, like an area the dog scratches all the time.
I suppose this is why their “lips” are (usually) black as well…
my dogs nose is red.
his name is rudolph.
at the dog park they all laugh and call him names.
never let him play dog games.
so he ran away to the isle of misfits with that little elf dude who wanted to be a dentist and some arctic lumberjack miner guy all dancing around until…
Dogs and seals both have similar noses and whiskers, and they bark and perform tricks. Dogs are land-based seals.
If you’ve ever had a dog with a light-colored patch on their nose (I’ve had two dog with light pink spots there), they are prone to sunburn. The rest of the dogs are covered in fur and the black skin doesn’t burn, but their poor little spots sometimes would.