All about gray cats

Gray is a word used to describe gloomy moods and rainy days. It’s the color of concrete and ash. It’s a hue decorators consign to “neutral” and dictionaries can only define by what it is not: neither white, nor black.

But in cats, gray is an astonishing color. From dove to oyster, and all the way to the deepest, darkest slate, gray cats of any shade are stunners. Emerald, gold, or sapphire eyes against a lustrous gray background only adds to the magic.

But how do cats come by their gray fur? Is gray a rare color for cats? And what cat breeds can be gray?

In this post, I focus on solid-gray cats, also known as “blue self” in the cat-fancy world. While there are cats with grayish stripes, cats with patches of gray, and cats with grayish points, the cats I’m referring to in this post are solid gray all over.

How do cats get gray fur?

Cat-color genetics are just crazy. You’re not even going to believe me when I tell you the two cat-color facts that need to be understood first, before you can understand how some cats are born with gray fur.

The first: all cats are either black or orange.

And the second: all cats are tabby cats.

You’re already shaking your head. I can see it from here. But believe me, we will get to solid gray cats by first talking about black, orange, and tabby cats.

Here’s some extra-credit reading if you want to know more:

All about black cats

Fun facts about orange cats

The tabby cat

All cats are either black or orange (underneath their “real” color)

Let’s take a giant step back in time, to your high-school biology class.

You might remember that we humans (and cats, and all other living things) have little packages of genes inside every one of our cells. These packages of genes are called chromosomes and they decide how tall we will be, what color eyes we will have, and whether we will be male or female, to name a few.

Chromosomes come in pairs, and we get one from each of our parents to make a set.

When a human baby or a kitten is conceived, it’s like rolling a pair of many, many, many-sided genetic dice. Random pairings of roughly 20,000 genes[1], that each come in a number of versions, is what makes every cat that ever lived unique.

In cats, black or orange will be on one side of each of those dice.

How is cat fur color determined?

If the roll of the kitten dice comes up with two blacks, the kitten will be genetically black. If the roll of the kitten dice comes up with two oranges, the kitten will be genetically orange. If the roll comes up with one orange and one black, the kitten will be calico.

Now, I’ve oversimplified considerably here.

Here’s one example of how I’ve oversimplified: there are actually several versions of the black gene and each one deposits more or less pigment on a strand of fur. One version is for jet-black fur, another is for chocolate-brown fur, and a third version is for cinnamon-colored fur.

There are lots more examples, but the bottom line is that every cat starts out with the genes to be either black or orange, or a combination of both.

Gray fur is the result of a special gene

In addition to different versions of the black genes, there are genes that “do stuff” to black and orange genes that change the color we see on the cat.

The dilution gene is one of those genes. It comes in two versions: full-color and dilute.

The dilution gene affects the density of fur pigment. The dilute version of the gene causes pigment to be deposited unevenly on a hair. The color ends up looking washed out or dusty. It reminds me of what happens when you put cream in your coffee.

If a cat with black genes also gets one or two of the full-color genes, the cat will get lots of pigment and will look inky black. The full-color version of the gene is dominant to the dilute version, meaning that if a cat gets one of each, the dominant version “wins” and the cat is jet-black.

But if a cat with the genes to be black gets two dilute genes, one from mom and one from dad, that cat could be solid gray.

All cats are tabby cats

I said earlier that there are two facts about cat coat-color genetics that you need to understand, before you can understand how solid-gray cats come by their unique coloring.

The second of those facts is that all cats are tabby cats underneath whatever coloring is showing on their fur.

So, solid-white cats are tabby cats, and colorpointed Siamese cats are tabby cats. Tortoiseshell cats are tabby cats, and tuxedo cats are tabby cats underneath their special colors, too.

Tabby-ness comes from the agouti gene

What defines a tabby cat is the agouti gene, which causes each cat hair to have stripes, or bands of color on it.

If you look at a tabby-cat hair under a microscope, you will see darker and lighter colors along its length.

The agouti gene causes these light and dark bands by interfering with pigmentation while that hair strand is growing.

The agouti gene allows a newborn hair to start off with dark coloring, but then it turns off the color spigot in the middle, forming a lighter band. And then it turns on the juice again at the end. Or vice versa.

The agouti gene is dominant, meaning a cat needs to get only one gene from one parent to look like a tabby cat.

But if a cat gets two non-agouti genes instead, there will be no gene to stop and start the hair pigmentation and the cat will end up being solid-colored.

Interestingly, the non-agouti gene isn’t a “non-tabby” gene. It just hides the tabby-ness. It often doesn’t work perfectly, which is why many solid-colored cats, even solid-gray cats, have ghost striping that shows through.

The genetics behind a solid-gray (self-blue) cat

So, let’s summarize.

In order for a cat to end up with solid-gray fur, three things have to happen, genetically speaking:

• The cat needs to get at least one gene for dark black fur from one of her parents.
• The cat needs to get two dilute genes, from both parents.
• The cat needs to get two non-agouti genes, from both parents.

Other grayish shades of cat fur

There are other gene combinations that produce grayish cats.

Lilac, also called lavender, even though it really looks almost pinkish-gray, happens when a cat with two chocolate genes also gets two dilute genes.

There’s another gene that only works on already diluted colors. It goes by three names: the dilute modifier, the caramelizing gene, and the double-dilute gene. It makes a cat’s fur even lighter, while adding a brownish tinge to it.[2]

A blue (gray) cat would become “caramel” with the addition of the dilute-modifier gene, while a lilac cat would become “taupe,” which may also be called “lilac caramel.”

Is gray (blue) fur rare in cats?

Even though it seems like a cat would have to win the genetic lottery to end up with solid-gray fur, gray cats are not that rare.

Alley Cat Allies, a community organization that works to improve the lives of feral cats, includes gray among its list of common base coat colors.[3]

But that might not be your personal experience with cats. In certain geographical areas, especially where there are a lot of feral cats, it would make sense that certain colors and patterns would appear to be more common than others.

When cats are mating with whomever they’d like, color genes that are within a group would tend to stay within that group, repeating themselves, generation after generation.

Unfortunately, there does not seem to be any worldwide statistics on cat color as a whole.

What cat breeds come in solid gray?

There are four cat breeds that absolutely must be gray. They do not come in any other colors. These are:

Korat

Chartreaux

Nebelung

Russian Blue

Cat breeds that may be gray, but also come in other colors include:

American Curl

American Shorthair

British Shorthair

Burmese

Cornish Rex

Devon Rex

LaPerm

Maine Coon

Manx

Norwegian Forest Cat

Oriental Shorthair

Persian

Peterbald

RagaMuffin

Scottish Fold

Selkirk Rex

Siberian

Sphynx

Turkish Angora

Why is gray sometimes called “blue” when referring to cat coat color?

Cat fancy seems to have its own language, especially when it comes to color. Orange cats are called “red,” cream-colored cats are called “fawn,” and gray cats are, seemingly inexplicably, called “blue.”

But cat-fancy people aren’t the only ones seeing blue where the rest of us see gray.

The smoke from an internal combustion engine, for example – a substance that looks gray to me – is often described as blue.[4] In the world of barbeque, “blue smoke” is considered the desirable effect of a clean-burning fire, one that enhances the flavor of meat.[5]

Physics explains why.

Smoke particles are so small that when light hits them it scatters, rather than bouncing straight back. Blue wavelengths, which are very short, scatter the most, and so those are the ones that we tend to see.[6]

I think it takes real imagination to see blue in a gray kitty, however.

And if “blue” cats aren’t really your thing, how about green? This poor kitty from Varna, Bulgaria had apparently been sleeping on a bag of powdered green paint in someone's garage.[7]

Is it “gray” or “grey”?

Actually, both spellings are correct. Gray is more commonly used by Americans, like me, but grey is preferred by those speaking British English.[8]  

The American manufacturing company, Crayola LLC, which makes crayons, and some might say define color for children everywhere, spells the color gray with an “a.”[9]

“Gray” and “Grey” are not interchangeable when they refer to a name, whether that is the African Grey parrot, Fifty Shades of Grey, the greyhound, Grey’s Anatomy, or Grey Goose vodka.

But you can have a gray cat or a grey cat, whichever you prefer.

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Dawn LaFontaine is a lifelong animal lover who always seems to have a little pet hair in her keyboard. Her blog, Kitty Contemplations, helps cat guardians better understand and care for the special beings they share their lives and homes with. Her cat-products business, Cat in the Box, sells beautiful, well-made, and award-winning products that she designed to meet the biological needs of cats.

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FOOTNOTES

[1] “Cat Genetics.” Wikipedia, Wikimedia Foundation, 28 Nov. 2023, en.wikipedia.org/wiki/Cat_genetics.

[2] Hartwell, Sarah. “THE BASIC SELF (SOLID) COLOURS OF CATS.” The Basic Self (Solid) Colours of Cats, messybeast.com/self-solid.htm. Accessed 29 Nov. 2023.

[3] Cat Identification Guide.” Alley Cat Allies, www.alleycat.org/resources/cat-identification-guide/. Accessed 29 Nov. 2023.

[4] “Why Does Internal Combustion Engine Smoke Appear Blue? Could There Be ‘Blue Molecules’ in It?” Chemistry Stack Exchange, 1 May 1963, chemistry.stackexchange.com/questions/71397/why-does-internal-combustion-engine-smoke-appear-blue-could-there-be-blue-mole.

[5] “Blue Smoke.” Destination BBQ, 21 May 2023, destination-bbq.com/glossary/blue-smoke/.

[6] Glass, Don. “Why Cigarette Smoke Is Blue or White.” A Moment of Science - Indiana Public Media, indianapublicmedia.org/amomentofscience/why-cigarette-smoke-is-blue-or-white.php. Accessed 16 Aug. 2023

[7] "The cat that got the green! Emerald-coloured stray turns heads after sleeping on heap of synthetic paint." December 4, 2014. https://www.dailymail.co.uk/news/article-2860846/The-cat-got-green-Emerald-coloured-stray-turns-heads-sleeping-heap-synthetic-paint.html

[8] “Gray vs. Grey: What Is the Difference?” Merriam-Webster, Merriam-Webster, k www.merriam-webster.com/grammar/gray-vs-grey-usage-difference. Accessed 27 Nov. 2023.

[9] “Gray or Grey - Are Both Correct?” GRAMMARIST, 27 July 2023, grammarist.com/spelling/gray-grey/.