Cat Coats Color Dilution

Cat coats color dilution.

We know that dilution means a watering down of a color. In painting this is achieved by the addition of water to color pigment so that the same amount of color pigment is spread over a wider area. What is happening to the color of a cat's coat when there is color dilution.

Perhaps a good starting point is to look at the hairs of the coat at a microscopic level in a before and after sequence. There are four basic solid (self in cat fancy language) dense colors: black, cinnamon, chocolate (see the cat right a Havanna Brown) and red (there are some green cats too apparently). Self colored cats carry the non-agouti gene. This is a recessive gene in homozygous form (aa). This allows black pigmentation (the substance is called eumelanin) to be produced throughout the hair as it grows. This is in contrast to the agouti gene, the presence of which results in banding of color in the hair. Taking the self (solid) color of black as a good example, the genotype is aaB-D-. B stands for the browning gene, which in dominant form (signified by a capital B) produces black pigmentation. The capital letter D stands for the dominant dense pigment gene. See black cats.

When the cat coat's color shows dilution it is due to the presence of the two recessive d alleles in the place of the dominant gene D (dd -called maltese dilution after cats imported from Malta in the early years of the cat fancy). This has an affect on the production of pigment granules in the hair. The granules become enlarged and uneven. This creates a dilute appearance. Diluted black produces grey (gray) as we know and in the cat world the color is called blue as it is a blue/grey (see the British Shorthair cat at the top of the post). There are some cats that are only grey - see grey cat breeds. Diluted chocolate becomes lilac, cinnamon becomes fawn and red becomes cream. The eye color remains unchanged.

Dilute cat coats can be further modified by the dilute modifier gene (Dm). This could be called double dilution. This gene only affects dilute cats coats. The diluted black that became blue then takes on a brownish color and is called caramel (hence the term that this gene "caramelizes the color). Lilac becomes taupe and cream becomes apricot. Of course the color white cannot show dilution (see cat coats white).

Solid color	Diluted	double dilution
black	blue	caramel
cinnamon	fawn	?
chocolate	lilac	taupe
red	cream	apricot

Cat Coats Color Dilution - Links:

1. Dilution affects tabby cats too. See cat coats tabby
2. You can see the blue color in the British Shorthair by clicking on this link.
3. The chocolate colored cat above right is a Havana Brown and you can read and see more of her (she is called Fraulein Katz - great name) by clicking on this link.
4. See a gorgeous black Maine Coon
5. See a blue point Siamese cat
   

Photographs: copyright Helmi Flick

Cat Coats Color Dilution - Sources:

• Messybeast - Sarah Hartwell
• Wikipedia
• Beth Hicks

From Cat Coats Color Dilution to Black cats

Cat Coats Tuxedo

Photograph copyright Mrs. Maze

Of the cat coats, tuxedo is another coat color/patten that is one or two steps up from solid black. They are a common type of coat amongst random bred cats but rare in my opinion amongst purebred cats (many breed standards don't allow the coat). A tuxedo cat as we might know is a black and white cat with tuxedo (human male formal suit of clothes) markings. Tuxedo cats are not a cat breed. Neither are calico cats, for example. These names describe coat colours and patterns not cat breeds.

This is usually a patch of white on the face (chin), chest, paws and belly. There is, in fact, a cat that is more black than a tuxedo and that is the "Locket Cat". He or she has a white patch where a locket would be if worn by a human and a small white patch on the belly. Apparently some cats can have only a few hairs of white, so they will be the nearest to solid black as is possible.

Lockets are called "brisket spotting" in cat fancy language. They are "minor white spots". The spots are "irregular in occurrence" and variable in size.  Sometimes they form streaks and they can be connected. It is not known if a single gene is responsible but it is thought that the cause is polygenic. Breeders eliminate this coat characteristic through selective breeding¹.

My cat is a tuxedo and so is my most recent stray cat who visits. She does not have much white fur. What causes a cat to have the black and white markings?

Tuxedo cat - My cat

The above photo is copyright free but please leave a credit (Michael at Pictures of Cats.org) and a link it you can.

A tuxedo is a bicolor (2 colored cat). There are an endless amount of possible permutations for bicolor cats. The term used to describe bicolors is a "Piebald cat". This is due to the gene that creates the white patches. This gene is the piebald gene or the "white spotting gene".

As the tuxedo or locket cat has white that covers less than 40% of the body the white spotting is called low grade spotting. The cat is still high grade though :)

The genetics of coat colors is a bit of a mine field and it would seem is not yet completely researched. However, the piebald gene is "semi-dominant with variable expression". To me this means its effect can take many forms.

My cat again!

It is thought that the gene dictates the spread of pigmentation during the embryonic stage of a cat's development. The gene affects the embryonic cells that become pigment producing cells. These cells start at the spine and migrate outwards. No pigmentation of the skin and fur will take place beyond the limit of the migration.

Accordingly, if the migration stops short of the entire body those areas beyond the limit of migration will be white (no pigmentation). As the paws and belly are the remotest areas from the spine these areas are more frequently without pigmentation and are white. The tuxedo pattern is thus formed. That's the theory at least. You will though see some tuxedo cats with white fur on or near the spine. These cats are better described as bicolor cats.

The tuxedo is a beautiful pattern but we are so used to it we sometimes fail to see its beauty.

Here are a couple of tuxedo cat pictures:

Tuxedo Cat - Photo by hz536n (Flickr)

The next photo is of a moggie that is also a show cat. You can show random bred cats as "household pets" at cat shows.

Tuxedo cat - Photo copyright Helmi Flick

Tuxedo cat facts -- Source:

• Messybeast
• Wikipedia
• Me
• 1. Robinson's Genetics at page 151.

Cat Coats Black Tortoiseshell

In the range of cat coats, black tortoiseshell is one step up from black. I am discussing all the cat coat colors progressively from black to white. This is the second post.

What makes for the black tortoiseshell appearance? Tortoiseshell is black and orange in various degrees of mix from a lot of black and not much orange to a lot of orange and not much black and the range in between.

There are in fact 3 things to discuss here: What turns the black pigmentation to orange? (Pigmentation means: Coloration of tissues by pigment. The pigment is minute granules in the hair and skin that absorb and reflect light to varying degrees to create different colors). What dictates the mix of orange to black? Why are tortoiseshell cats almost always female?

1. Black to Orange

This happens through the actions of a gene called the O gene. This gene causes the black pigment to become reddish. Red is also, orange, in the cat fancy.

2 and 3. The Mix of Orange and Black and female torties

The answer to this is linked with the answer to why tortoiseshell cats are female. The O gene mentioned above that changes black pigment to red is carried on a sex defining Chromosome, the X Chromosome. You may know that our sex and the sex of cats is dictated by the sex Chromosomes X and Y. Males have XY make up and females XX.

As the O gene is carried on the X Chromosome, only one O gene is required for a male cat to be ginger (orange). The female requires 2 copies of the O gene for her to become ginger (all over that is).

If she inherits only one copy of the O gene she becomes partly ginger or as the cat fancy say, tortoiseshell.

That leaves the question as to how much of each color there is. In other words is she going to be a black tortoiseshell (much more black than orange) or the converse?

This last factor in the tortie recipe is controlled by X Chromosome Inactivation. In cats with 2 X Chromosomes (females), some of the cat's cells activate the O gene and other cells activate the O gene in the equivalent place on the other X Chromosome. As this process can only occur where there are 2 X Chromosomes (female genetic make up) only females can be tortoiseshell (except for the odd anomaly).

In the black tortoisehell cat the number of cells activating the O gene is less than in a cat that has more orange in her coat. That is why she is a black tortoiseshell cat.

Update: 17th December 2008 -- see some fine tortoiseshell show cats on this page plus some more info...: Tortoiseshell cats.

Photographs:

• Top Black Tortoiseshell cat Skittles copyright and by Gini~
• Middle Black Tortoiseshell copyright and by cygnoir
• Bottom tortoiseshell headband copyright and by LensENVY

Source:
MessybeastWikipediaAbout.com

Black Cats

What makes a black cats black and where do they stand in the huge range of cat coat colors? There is a bewildering array of cat coat colors. I thought that I'd do a series of articles on the spectrum of colors all the way from Jet Black to Ice White, starting at black. In addition, the patterns will be discussed as these break up the solid colors.

Black cat in the snow. Picture in the public domain.

A cat's coat is black because the pigmentation in the fur absorbs a substantial amount of light, whereas in a white cat the opposite is the case, the light is reflected.

Cat coat colors are based on genes that produce the colors, black and red and variations of these. The variations are made by modifier genes, which dilute the colors. Examples would be red turning to cream and black turning to blue or chocolate. In addition, there are genes that produce the patterns (Agouti "A" gene) and genes that create white fur, the white spotting gene.

It is the interplay between these genes that determine coat color.

Black cats are called "solids" in the cat fancy. The solid color breeds (also called "selfs" but I don't know why) have colors, black, blue, chocolate, lilac, cinnamon and fawn. The black color is due to the presence of microscopic granules in the hair (black pigment), which absorb the light. In a black cat these granules are called eumelanin or 'melanin' for short. They are spherical in shape.

Black cat. Shiny coat. Photo in the public domain.

The Genes

It is thought that the black cat is a very early mutation from the wild cat tabby coat. Robinson's Genetics says that the black coat is a result of a change (mutation I presume) in one of the genes that dictates the agouti background color. This is because the individual hair strands do not have the banding of yellow pigmentation that is produced by the Agouti gene and are instead mainly black throughout. Any color change of the hair is at the base near the skin where it will be grey (smoke like color).

The browning gene dictates the production of eumelanin in black cats. When the gene is dominant the cat is black. There is also the action of the recessive non-Agouti gene (aa) that suppresses the more natural effect of banding on the hair follicles resulting in solid color. In fact, all self-colored cats have the non-agouti gene shown as aa.

Black Maine Coon with some rust. Photo: Ekaterina Sansaverina Gold. Black is one of the basic self-colours.

RELATED: Rusty red black cat fur caused by defective pituitary gland?

The genes present in black cats are then the non-agouti recessive aa, plus the gene producing black pigmentation B, plus another gene symbolizes by D for dense coloring. A black cat will have these genes present. The non-agouti is always recessive while the alleles of genes B and D can be present as both dominant (BB, DD) or one dominant and one recessive (Bd, Dd).

RELATED: Are black cats friendlier?

Cat breeders will seek a jet black but sometimes a rusty brown tinge is shown. Black Cats showing this phenotype (appearance) would normally be excluded from the breeding program unless there is a pressing reason as to why not. An influence on the density of black coloration is sunlight. Apparently, sunlight and the saliva deposited when grooming combines to oxidize the pigmentation to produce a brown tinge.

You can see a rare black Maine Coon cat by clicking on this lick. If we go up the scale of colors to the next level we would probably have the Black Tortoiseshell coat (Tortie) see the picture right. Tortoiseshell is a mixture of the base colors referred to above, black and red. Both these colors are apparent on the coat. The introduction of the red (or more commonly called orange) breaks up the solid black coat.

Finally, it is thought that as the most natural coat color/pattern is the Tabby (as it is the best in terms of camouflage), possibly the first genetic mutation (affecting a cat's coat) was from that natural state to black.

You can see all the posts on coat colors by clicking on this link.

Photograph bottom tortoiseshell copyright and By Gini~

Part of the information for this post has come from Robinsons Genetics