Some info on the skin pigment...
Nose and skin pigmentation
Because Lab colouration is controlled by multiple genes, it is possible for recessive genes to emerge some generations later and also there can sometimes be unexpected pigmentation effects to different parts of the body. Pigmentation effects appear in regard to yellow Labs, and sometimes chocolate, and hence the majority of this section covers pigmentation within the yellow Lab. The most common places where pigmentation is visible are the nose, lips, gums, feet,tails, and the rims of the eyes, which may be black, brown, light yellow-brown (”liver”, caused by having two genes for chocolate),[11] or several other colours. A Lab can carry genes for a different colour, for example a black Lab can carry recessive chocolate and yellow genes, and a yellow Lab can carry recessive genes for the other two colours. DNA testing can reveal some aspects of these. Less common pigmentations (other than pink) are a fault, not a disqualification, and hence such dogs are still permitted to be shown.[11]
The intensity of black pigment on yellow Labs is controlled by a separate gene independent of the fur colouring.[11] Yellow Labs usually have black noses, which may gradually turn pink with age (called “snow nose” or “winter nose”). This is due to a reduction in the enzyme tyrosinase which indirectly controls the production of melanin, a dark colouring. Tyrosinase is temperature dependent—hence light colouration can be seasonal, due to cold weather—and is less produced with increasing age (two years old onwards). As a result, the nose colour of most yellow Labs becomes a somewhat pink shade as they grow older.[11]
Both of them have dark spots where their tails connect to their hind end.