The default eye color for dogs is brown, however, a number of genes can affect eye color.

Amber eyes usually occur when the eumelanin in the coat is diluted or modified by the recessive genes in the B or D series. All chocolate dogs (bb) have amber eyes, as do blue and isabella dogs (dd). Amber eyes vary from light brown to yellow, yellow-green or grey.

Genetically, there are a number of ways in which a dog can have blue eyes. The most common way is an effect of the dapple gene. Dapple dilutes random parts of the pigment, including the eyes and nose. This sort of dilution causes blue color in the iris.

Another way that blue eyes can occur is when a dog has large amounts of white around its eyes. White areas on the coat are where the cells are unable to produce any pigment, so if these areas spread to the face then there may be pigment loss in the eyes and on the nose, making the nose pink and the eyes blue.

When a dog is affected by one of the stronger genes from the C group its eyes can be blue. The C group is albino. There are no confirmed cases of true albinism in dogs, but there are many stages which do occur in dogs.

heterochromia iridium - One eye is one color and the other eye is another color. Also called split eye. This is usually caused by dappling.

pearl eye - A partially depigmented iris. This is usually caused by dappling.

cracked eye - An iris of one color that has a line or segment of another color going through it. This is usually caused by dappling.

marbled eye - An iris of one color that has lines or segments of another color going through it. This is usually caused by dappling.

china eye - An otherwise totally bluish iris that is flecked with lighter blue or white.

heterochromia iridis - An eye that has more than one color in it.

wall eye - A totally bluish or grayish/whitish iris and a dark pupil. This is usually caused by dappling. Wall eyes are when a dog has one blue eye and one brown or amber eye.

glass eye - A totally bluish or whitish iris and a bluish pupil. This is abnormal.

cloudy eye - Any color iris and a partially or totally bluish, grayish, or whitish pupil. This is abnormal.

eccentric pupil or dropped pupil - A pupil that is not centered in the eye; it is usually lower in the eye. This is usually dapple-related.

irregular pupil - A pupil that is not round. This is usually dapple-related.

starburst pupil - A pupil that is shaped like a starburst (has rays extending out from it). This is usually dapple-related.

iris coloboma (a type of iris hypoplasia) - Part of the iris is missing, usually in the form of a pupil that extends in one direction over the iris (where the iris should be). This is usually dapple-related.

Nose

The default nose color for dogs is black, but a number of genes can affect nose color.

Chocolate (bb) dogs and dilute chocolate (isabella, dd) have noses ranging from deep brown to pink. It is genetically impossible for a chocolate dog to have a black or blue nose.

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.

This is usually caused by dappling, or double dappling. 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. Butterfly noses are created when parts of the nose have no pigment. The dapple gene dilutes parts of the pigment on the nose, creating pink areas on the nose.

The entire nose completely lacks pigment. The color will be pinkish or reddish because of the blood showing through the skin. This sometimes is caused by dappling, or double dappling, but it is often caused by simple lack of pigmentation.