Blue (the "d" Influence)

While we just looked at "D" in dominant, Black form, now we will look at a recessive form. The recessive expression of the "D" (dilute) series is a colour well known as 'Blue'. This colour is also often described as 'grey' and is, put simply, a diluted form of Black. What differs to our diluted Black-to-Brown colouration is the end resulting colour. The dilute blue series is separate to the dilute brown and while they do work together (later to be discussed) generally we see one expressed over the other.

Here we see a beautiful example of a 'dilute Black' (Blue) Pit Bull Terrier. It is very apparent that the coat colour is simply 'a light shade of black' - perhaps as one might describe the colour grey. Blue dilute dogs range in shades of dilute black and some, darker coloured Blues may often be hard to distinguish from blacks, except when in certain lights. Most Blues, however, are a similar shadeas can be seen in our Pit Bull.

Another thing this photo depicts is the whole body dilution that can be seen - in the same way a "b" diluted dog is chocolate-coloured pigmented. Dilute Black 'Blue' results in all pigment being diluted, which causes the blue colour. (As can be seen.) This means that coat colour, nose, eyerims and eye pigment is also affected (diluted).

Here is an example of how the 'blue' dilution also affects the eyes. Note the lack of dark pigment around the eyerims. As well as this, the eye pigment itself has also been altered. It is not uncommon for a Blue coloured dog to have amber, green, and sometimes, blue eyes. Darker colours are obviously only as dark as the coat's melanin allows. The nose (as can be seen in the first photo) is very similar in colour to the coat. Sometimes it may appear as though the dog has a shade of 'purple' to the coat. This is for a few different reasons, explained later. One important thing to quickly make note of - genetically, blue dogs are not, ever, "bb". They can indeed carry the browning gene, as well as express it alongside the blue dilute gene, however - this actually changes the appearance of the colour and is refferred to as a separate colour.

Here is a dilute Black ('Blue' - as we will now call them) Great Dane. Similar to the Great Dane used in the previous post, this Dane does have one obvious difference - its coat colouration. This Dane is expressing the dilute influence, which means its phenotype will be "dd". As we established Great Danes rarely carry chocolate, we can now establish its phenotype is: "KK" "BB" "dd". This dog is a carrier and expressor of Blue.

Just to illustrate the distinct differences between a dominant Black dog and a dog with the dilution gene, here is a photo of two Doberman Pinschers. It is apparent which is which. The blue dog is very obviously blue, with the distinctly diluted nose, fur, skin and eyes. Notice though, that the tan points are just as red as the other dogs. This is because this form of red is not affected by black. More on that later.

More Dobermanns! These puppies also express the dilution gene. One thing to note, here, is that they are all littermates, and that it is possible to get blue puppies from non-blue (Black) parents. These, of course, must each have one set of the dilution gene ("d") for this to occur. These blue puppies will be "dd", and the other puppies a combination of "Dd" (carrier, not expressor), or "DD" (dominant Black.)

Another Doberman. This dog, as the above Dobies, is also Blue. Now let's look at the possibly phenotype for this dog. Because this dog is expressing tan points, as do all Dobies, we know it is "kk" (tanpoints are expressed on 'k'). The dog may be either "BB" or "Bb" as red is common in this breed. It is also "dd". So, we have established our phenotype is now: "kk" Bb" "dd".
Blue Dobermans, as other blue dogs, are known for having skin and coat conditions. This is caused by the apparent lack of pigment (melanin).
Blue coloured dogs also appear to have coats that do not shine, and, isntead, may seem to have a dull or soft coat.

A pair of Blue Lacey's. We can see that this puppy is clearly blue ("dd") and has no tan points. ("Kk") The dog sniffing it is a red dog, however it is not affected by the "B" influence. This dog is actually Red Sable, which is affected by the "k" (agouti) series - to be discussed further on.

Here I will quickly include some examples of dogs falsely thought of as 'blue'. This dog, a Rough Collie, is what one might describe as 'Blue, Tan and White'. The Tan and White part it correct, however, this dog is actually "DD" and does not express the dilution gene. Despite its coat looking blue, it is genetically Black and White, modified by the merle gene. Despite this, these dogs are still called 'Blue Merle.' Note, however, the dog's nose and eyerims - dark black. This is not a blue dog.

One more example - a Stumpy Tail Cattle Dog. A separate breed to the ACD, this colour is also describes as 'Blue' by many people/ This is actually false, as there is not one blue hair on this dog. The Australian Cattle dog is "DD" and affected by what is known as the roaned/ticking gene, as well as expressing extreme piebald (a large expression of white). What this means is that the ACD is a black and white dog genetically, and appears blue because the hairs mingle together with varying degrees of darkness. It is basically an extremely ticked dog.


And there we have - the blue/black dilution influence. Next we will look at what happens when the recessive Brown ("bb") and recessive black/blue ("dd") genes are combined, and the colouration effects of this process.