Wednesday, 9 November 2011

Coats of many colours

Coat colours and patterns in the Norwegian Forest Cat

The face of a silver tortie tabby and white kitten - she has
red, black, white and silver colours in her coat

At cat shows, NFCs get no points for colour, although a few colours are not allowed (eg chocolate, lilac or Siamese pointing).  However it is interesting to be able to understand what colours might appear from a particular mating.

All cats have eight pairs of genes that affect how their coats look in terms of colour and pattern. One gene from each pair comes from the cat’s mother, and the other from the cat’s father. Some genes dominate over others.  For any recessive gene to “work” it has to be doubled up - e.g. a cat with one (recessive) dilute and one (dominant) non dilute gene will not look dilute. This article ignores the “new colours” – amber and light amber, previously known as the “x” colours – as they are different, recently discovered and probably unique to NFCs.  I have not worked with amber or light amber as I don't particularly like them, but I have had kittens of all other possible colour combinations over the years.

1. Black, which is the base colour
All cats are really black cats in disguise!  The other genes, 2-8, listed below modify appearance.  
Hey, I'm unmodified!  So I look black all over.  And I'm four weeks old, so there.
2. Orange or not Orange?
Although we call the colour red, genetically it is given the code O for orange (or a small o for not orange). O is a sex linked gene. It attaches itself to the X chromosome. Males are XY and females are XX. So if a male is red, then when he has a daughter he always passes on his X chromosome to her, and hence always passes on his O gene. That’s why the female kittens from red studs invariably have some red fur.
The kitten on the left is a red and white girl fathered by a tortie mother
and a red  tabby and white father
A female with one red gene will be a tortie. A female with two red genes (which she has to get one from her father and one from her mother) will be red.
Red has a complication in that the way the pigment works on the cat hair means there is always a tabby pattern evident. Hence it is difficult to tell visually if a red or cream cat is tabby or not.
A variety of Vieuxtemps kittens including a cream tabby boy, right - cream is the
dilute version of red.  (The funny little white one from a different, younger, litter!)
3. Dilute or non dilute?
The red or black is affected by the dilute gene to produce cream or blue respectively. Dilute is recessive to full colour. So if you have a dilute cat, both genes on this locus must be dilute. If you have a full colour cat, it may be carrying one dilute gene. If a full colour cat had a dilute parent, it MUST carry a dilute gene. If a cat doesn’t carry a dilute gene, then mating it with a dilute cat will never produce dilute kittens. However dilute genes can be carried from quite a long way back in the pedigree. D = dense, d= dilute. So DD and D cats do not look dilute – dd cats do look dilute.
Ragna, a dilute cat - she was a blue ticked tabby
4. The White Spotting Gene
Designated S and so called to distinguish it from the completely separate white masking gene – the spotting gene gives the Forest Cat white areas on its body. This can be completely variable, from a tiny white tip on the tail to nearly all white with just a few coloured blotches.  The white patches don't have to be actual spots! The typical look is white inverted V on nose and white paws and tummy. There are no rules as to where and how much white should appear. The spotting gene is dominant. Hence you cannot get a kitten with any white areas unless at least one parent has the white spotting gene.
This white queen (who clearly has the white masking gene, but we cannot see if she has the white spotting gene) has a brown tabby kitten, snoozing bottom right, who clearly has the white spotting gene giving him the white 'V' on his face typical of many NFCs.
5. The Inhibitor gene - silver/smoke or not?
The inhibitor gene I prevents pigment from colouring the bottom part of every hair shaft. Hence if you look at the roots of hair of a silver or smoke cat, they should be pure white. However there are many grades of silver, and as no-one tends to breed NFCs for colour (as colour has zero points in the Standard of Points) you do sometimes get very low-grade silvers where it is difficult to see. Some cats like this are wrongly registered but will later produce silver progeny with a non silver stud, which means they have to be re-registered correctly. Smoke and silver are the same, except for the fact that silver is tabby and smoke is solid colour. The inhibitor gene is dominant (as far as we know). Other forms of smoke –eg the very slight colour tipping of Chinchillas, are not found in NFCs.
Tarnishing – it is wrong of judges to punish unless as a point of dividing otherwise equally good cats. Silver and smoke can combine with any colour –eg red smoke, blue silver and so on. If speaking of a silver tabby cat, one is referring to the default black silver.
Vieuxtemps Rosa, silver tabby and white kitten aged eleven weeks
6. Tabby or non tabby?
Do not confuse the gene that says that a cat shows a tabby pattern or not with the gene that says which particular pattern the cat has (see 7 below).
Tabby is dominant over non tabby.  In genetics, the word Agouti is used for tabby and the gene has code A (tabby) a (non tabby).
A cat without the Agouti gene means it will appear solid coloured. Cats cannot carry the Agouti gene. So two solid cats can never have tabby offspring. Tabby cats can carry solid genes however, so two tabby cats can have solid offspring.
The effect of the Agouti gene on a black coat is to make the black brown. Hence, a brown tabby cat is genetically a black tabby (which is the term used in FIFe).

This brown tabby and white kitten, Vieuxstemps Snygging, is technically
black and white with added tabby!
7. What tabby pattern?
There are four patterns:
All NFCs have a pair of tabby pattern genes, even if they do not have the gene that makes them a tabby cat. Sometimes “ghost” markings can be seen in solid coloured kittens, in some lights. The markings can always be seen in a red or cream cat, regardless whether or not it is tabby.
Spotted is actually classic or blotched, but with a broken pattern. In other breeds (such as Bengals) there are other spotted genes (eg rosettes, like leopards) and also the marble pattern, but not in NFCs.
Classic is recessive to mackerel, and mackerel is recessive to ticked. Ticked coats are sometimes known as “wild pattern” abroad as they are similar to the coat of a wild rabbit, hare, fox etc. There are no stripes or spots but instead each hair has several bands of contrasting colour, with the darkest colour at the tip.
There is some controversy over ticked tabby NFCs outside of Norway. Some people suspect that Somalis have been bred with NFCs to get this pattern. However going back to ticked novices, they were found in the Norwegian countryside the same as the other patterns. We do not know what is behind any of our Forest Cats but we do know that the Vikings travelled to places where there were ticked cats.

Silver tortie tabby girl showing classic tabby pattern
8. The White Masking Gene
You can think of the white masking gene as being a white overcoat on top of the cat’s normal colour. A white cat can be any other colour underneath the white. Eye colour is affected – eyes are blue, green, orange/yellow or blue plus one of the others(“odd eyed”). The eye colour inheritance seems completely random although blue eyes are associated with a slightly greater incidence of deafness. If a cat is solid white, it has at least one W gene, which is dominant. If the cat isn’t white, it must have two white w genes (ie non white masking). This gene is associated with deafness (but the majority of white kittens can hear). I used to specialise in white NFCs because I think they are so very beautiful, but I stopped using them for breeding as although very few of my kittens were deaf I just didn't want to breed deaf kittens.
Kyrrekatt Kohinoor, one of my very first Forest Cats
(photo by Kevin Reah)
If you are a novice breeder and need guidance about which colours are likely to appear out of any particular mating, you are welcome to contact Mary-Rose for help.

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