EYE COLOURS
The default eye colour for dogs is brown:
However, a number of genes can affect eye colour.
AMBER EYES
Amber eyes usually occur when the eumelanin in the coat is diluted or modified by the recessive genes in the B or D series. In other words, all
liver dogs (bb) have amber eyes, and so do blue and isabella dogs (dd). Occasionally dogs with black pigment also have amber eyes, but in general they're found just on
livers and dilutes.
Amber eyes vary from light brown (overlapping with the lighter eyes sometimes found in black-pigmented dogs) to yellow, yellow-green or grey.
Liver agouti/grizzle Siberian Husky with amber eyes.
A recessive red (rr) Nova Scotia Duck Tolling Retriever. Its pink nose and eye rims and amber eyes give it away as being liver (bb) rather than black.
Blue (dd) sable or creeping tan Italian Greyhound with very light, greyish eyes which appear to match its coat.
Isabella (dd) Slovakian Pointer with very light eyes which also appear to match its coat.
BLUE EYES
Genetically, there are four ways in which a dog can have blue eyes. Three of these are linked with pigment loss in the coat.
The most common way is as a side effect of the merle gene. Merle dilutes
random parts of the pigment, including the eyes and nose. This sort of dilution causes blue colour in the iris (contrary to common belief, animals with no
pigment around their eyes do not always have pink or red eyes like albino rodents do - lack of pigment or very diluted pigment often results in
blue eyes, as it does in albino humans). Because of the random pigment loss, often merle dogs have "butterfly" noses (see nose page) and blue, wall or split eyes. Wall eyes
are when a dog has one blue eye and one brown or amber eye, and a split eye has some blue in it and the rest is brown or amber. Split eyes vary from mostly
blue to mostly brown or amber.
The more dilution there is in the coat of a merle (i.e. the more grey/diluted areas), the more likely they are to have blue eyes or a butterfly nose. A heavily
merled dog (large areas of black or liver) is unlikely to have either of these traits. Double (homozygous) merles are highly likely to have blue eyes and a completely
or almost completely pink nose because of the combination of merle dilution and large amounts of white around the face (see below).
This red (liver) merle Aussie has one amber eye (because of its bb liver pigment) and one blue. If you look carefully you can see a sliver of amber in the blue eye.
This red (liver) merle Border Collie has a striking milky blue eye.
This harlequin (modified merle) Great Dane also has a blue eye.
This Border Collie is a sable merle. He has very little visible merling, but his blue eyes give him away as a merle.
This is a Beauceron with relatively heavy merling and no white. As you can see, his eyes are dark brown.
The second way in which 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. This only tends to occur on very high-white dogs with the extreme spotting pattern, such as white Boxers.
The third way is when a dog is affected by one of the stronger genes from the C series. The C series is albino. There are no confirmed cases of true albinism in dogs, but there are many intermediate stages which do occur in dogs. Some of the genes in the C series affect only the phaeomelanin (red) in the coat, diluting it to cream or white but leaving the nose black (or liver, blue or isabella) and the eyes brown (or amber), but there is also at least one gene which dilutes all the pigment on the dog almost to white. This is the closest the dog world comes to albino, and it is known to occur in at least Dobermanns. "White" Dobermanns have a very light coat (with the main coat appearing as a very light isabella colour and the tan points light cream), blue eyes and a fully pink nose.
This Husky is probably not an albino of any kind, but just a very poorly pigmented liver. However, it gives a good idea of how an albino would look -
white coat, completely pink nose, pink eye rims and blue eyes. This dog doesn't actually have red pupils (even an albino dog probably wouldn't have them) -
it's just the shine in the eyes from the flash on the camera - blue eyes usually shine
red, and brown and amber eyes shine yellow or green.
Lastly, blue eyes can be inherited as a completely separate gene, unaffected by coat colour. This gene is, however, rare. It is rumoured to occur in the Border Collie, but mainly it's seen in the Siberian Husky. Huskies can have one or both blue eyes, regardless of their main coat colour, ranging in shade from almost white to sky blue. This is particularly striking when seen on black dogs.
These two Huskies have almost identical coat colours, but one has deep brown eyes and the other has blue:
As you can see, both dogs have full black nose pigment and black around the eyes (eye rims), so the only explanation for the blue eyes on the dog on the
right is that they are inherited separately to coat colour and pigmentation.
A Husky with wall eyes.