I've noticed that in some cases when a dog is black, at least to my eyesight, they are described as being blue. Here is, I think, an example of this, in a Doberman:

enter image description here
This photo on Wikipedia is captioned "Blue Doberman Pinscher".

I know you might say that the colors in the particular photo give the impression that it has a black coat as opposed to blue, but I recently saw the papers of one dog that had "blue and white" written for "color" when I could swear it was black. I stood there a while, closely looking at what was supposed to be its blue-colored hair/fur, looking at it from different angles to see if the light made a difference, and either I must be colorblind or it was black, not blue.

Does anyone know why seemingly black hair/fur on dogs is called blue?

  • for me the "blue" dogs look like black ones, with a thin layer of gray dust on their fur... like black cars, which are not really black anymore, because they need a wash. This is for me most notable if I view in a small ankle onto the surface. If I look 90° on the plain surface, I barley would notice it, but if my cheek nearly touches the surface, then "the dust" is obvious. – Allerleirauh Dec 16 '20 at 12:39

Blue is actually a distinct color caused by the normal black pigment called eumelanin being muted by a distinct mutation or mutations near the melanophilin gene (MLPH). http://caninebreeds.bulldoginformation.com/blue-dogs.html. This results in a gray color that's distinct from other grays found in dogs. The blue color can vary from lighter to darker, or it can even be mottled, which is known as "blue merle."

I suspect that the reason you're having trouble discerning the difference is that color perception is actually a learned skill, and can be surprisingly subjective. For instance, some cultures cannot discern between as many colors as others, when there is no biological reason for this. A really good demonstration of this phenomenon is the internet meme of a few years ago, is it a gold and white dress or a black and blue dress? The meme was a photo of a dress, which due to the very particular light conditions, made people perceive the dress as very different colors, almost half and half thinking it was gold and white versus black and blue.

It may also be the case that you have trouble seeing the difference when the blue dog is on its own, but you could tell the difference if you saw another dog of the same breed but black instead of blue, standing next to it.

  • There are some interesting points I want to address. The blue color of the Dobermann is referred to as "dilute black". Here are some examples of the "dilute black" blue: doggenetics.co.uk/dilutes.html . Are you saying that, for example in the first image (the border collie), the coat's color is actually blue, not black, and that it's a learned skill to identify that color as blue? Secondly, the dress example is a head-scratchingly unique thing unexplained and unreplicated by vision scientists, are you saying there's the same level of subjectivity in identifying those dog colors? – Zebrafish Jul 4 '19 at 2:22
  • More like how you identify a specific color in general can be subjective. For example, from comparing my opinion of what is pink versus purple I've realized sometimes what I think is a purple others think is a pink. It may be the case that similarly that what most people see as a shade of gray is categorized as black for you. Also, while I say it's a learned skill, it's one of those that's set at a very early age. Experiments to have an older person identify a color not recognized by their culture usually do not work. – Kai Jul 4 '19 at 4:25
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    Although, one other thing, when you're talking about images on a monitor, it could be also that your monitor really is displaying darker than other people's. =) – Kai Jul 4 '19 at 4:27
  • Yes, I agree with everything you say. In the case of calling a dog blue or black, since I've read that this diluted blue condition results from from a certain combination of recessive and dominant gene alleles, and given the fact that (from what I've read) this "diluted blue" condition (or color or whatever you want to call it) expresses itself as a color from silver to near black, I'm tempted to think that a vet bases their decision of color based on the genotype rather than looking at the actual color of the fur. One way I've read this can be done is by looking at the color of the nose. – Zebrafish Jul 4 '19 at 5:14
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    I think the confusion is partly that even though the 'blue' coat of a dog is distinct from black -it also doesn't look blue in the way we normally define it-. There is no sky, cerulean, or even navy blue look to it. It's called blue, but relative to every other use of the word... it's not blue at all. I would call it 'dark slate gray', if anything. It's known as blue essentially by tradition. Likewise, a lilac point Siamese cat has light silvery gray points, no actual pink/purple color of the lilac flower in it. – Meg Jul 8 '19 at 15:35

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