Why are dogs' noses wet?

While the noses of many dogs are wet, plenty of dogs have dry noses.
What keeps a dog's snout moist? No one knows for sure. one theory says that the wetness comes
from mucus produced inside Fido's nose. Another hypothesis suggests the because dogs lick
their noses all the time, saliva keeps their noses moist. Despite popular belief, a warm noes does
not mean a dog is sick.