NOSE COLOURS
The default nose colour for dogs is black:
However, a number of genes can affect nose colour.
LIVER
Liver (bb) dogs and dilute liver (isabella, dd) have noses ranging from deep brown to pink. It is genetically impossible for a liver dog to have a black or blue nose.
Colour range in liver dogs:
Colour range in isabella dogs:
BLUE
Blue (dd) dogs have noses ranging from light grey to almost black. It is genetically impossible for a blue dog to have a brown nose. Note, however, that sometimes grey dogs can occur that don't have the blue dilution gene. So an apparently "blue" dog may have a black nose and dark eyes, because in fact it is a black dog with the greying gene rather than a proper blue dilute. Sometimes blues can also be very dark, so that their coat and nose appear almost black. It can be very difficult to tell whether such dogs are blacks or blues.
Colour range in blue dogs:
BUTTERFLY OR PARTI NOSE
A "butterfly" nose is when a dog has patches of bright pink on its nose leather. These patches are randomly located and can cover any
amount of the nose, from just a tiny pink spot to almost the whole nose. Butterfly noses sometimes occur on dogs with the extreme white spotting pattern (
e.g. white Boxers, Bull Terriers and Dogo Argentinos), but generally they're associated with merles. Not all merles have butterfly noses though - double merles
and normal merles with less dark patches than normal are more prone to them, and they are very common in harlequin Great Danes.
Butterfly noses are created when parts of the nose have no pigment (the colour pink is associated with a lack of pigment). The merle gene dilutes random parts of the pigment on the coat and nose, creating
grey areas on the coat and pink areas on the nose. Harlequin Great Danes have an extra gene which dilutes the grey areas on the merle to white, so this extra
strong dilution means harlequins are highly likely to have a butterfly nose.
The non-pink parts of the nose can be liver, blue or isabella if the dog is bb (liver) and/or dd (dilute). Livers and isabellas often have very light noses
anyway, sometimes bright pink, so a butterfly nose may not show up on a liver or isabella merle (the whole nose may just appear pink). The last example
below shows a liver merle with a visible butterfly nose.
DUDLEY NOSE
Sometimes, in specific breeds such as the Bull Terrier, the term "dudley nose" is used to describe a dog with a pink nose due to high white on the face (see butterfly nose above). However,
usually it's used to describe a dog with pigment loss on its nose.
Generally the pigment loss on a dudley nose is in the middle of the nose, spreading outwards to cover almost all of the nose on some dogs. The pigment
loss causes the nose to become lighter in these areas, usually ending up as a dull pink. Dudley noses never lose their pigment completely and are never
as bright pink as butterfly noses or even the pink noses found on liver dogs. There is also always a darker area remaining around the edge of the nose.
Dudley noses are generally seen on dogs with solid black noses only, simply because the lighter pigment on liver, isabella and blue dogs means that
areas with pigment loss are very hard to see. They are, however, very common on black-nosed dogs, including show dogs. The last three pictures below show
two liver dogs and an isabella dog which appear to have dudley noses.
SNOW NOSE
Also known as a "winter nose", this is a dudley nose that appears during the winter months, or sometimes as a result of stress or other factors. Dudley noses are permanent, but snow noses are not.
NOSE INJURY
Injury to the nose can sometimes result in pigment loss, either permanent or temporary.
This Eurasier has injured its nose, probably quite recently. You can see stripes of pink and red where the pigment has been damaged.