RUSSIAN SUNSHINE - GOLDEN COLOURS IN SIBERIAN AND KURILIAN BOBTAIL CATS
This page results from a discussion on the inheritance of black tail-tips in some red/red-tabby Kurilian Bobtails. The first issue I noted was that the cats' colours were registered as golden shaded/golden tabby when a visual inspection shows them to be torties or reds. In addition, the cats bred as torties and reds!
In 2014, Anna Hakkarainen wrote to me about some curiously coloured Russian-bred kurilian Bobtails. Some Russian breeders have kurilians that display amber-like colors (the late black-to-red colour change seen in Norwegian Forest Cats). Anna had encountered kurilian kittens that were born reddish with a black tail-tip. This occurred when both parents were registered as "golden" (e.g. golden shaded, golden tabby) which many in the cat fancy understand to be related to the silver inhibitor gene and expressed when the wide-banding gene is also present.
At first we wondered if it was some type of birthmark, but it was curious that several cats had black-tipped tails. Then we wondered if the dark shading was somehow restricted to the tail-tip, with a black-to-red colour-change occurring before the kittens were born. We knew that greyish pigment can occur on red cats on the tail, face and feet, perhaps due to temperature. Then we looked at the pedigrees as well as photos of the cats concerned, and we noticed discrepancies between the phenotypic (visually expressed) colours and the colours registered on the pedigree! The appearance of red/red-tabby cats that followed the rules of inheritance for the sex-linked red gene, but whose parents were allegedly golden shaded/golden tabby cast doubt on the registered colours of parents and grandparents.
We put aside the black tail-tip as a curiosity for the time being and opened up a can of worms. Because of breeder sensitivities, I can't use photos of the actual cats whose pedigrees don't reflect their actual colours.
WHERE DID THE REDS COME FROM?
Below is the pedigree of an indisputably red-and-white cat that is registered as “black golden shaded.” The problem seems to come from the mother's side where a phenotypic spotted tabby-tortie has been registered as a black golden spotted tabby, but produces red kittens with black tail-tips. She also produces red-tabby-and-white female offspring which demonstrates that she has to be a tabby-tortie (and have the O gene for red colour) and not a golden tabby. Anna I also found a shorthaired red-tabby-and-white male kurilian Bobtail (with a dark tail-tip) that was registered as a black golden blotched (classic) tabby with white. Show judges in Russia have also voiced concern over such cats not being the colour it says on the pedigree papers.
Chart showing Pedigree vs Phenotype.
Mistakes early on in a pedigree propagate throughout later generations until it becomes impossible to explain away the indisputable red cats later on. That's when it's necessary to work backwards and re-evaluate the colours of the parents and grandparents.
Maybe there is a terminology error regarding "golden" with the term being used to describe different things. Some breeders register their warm-toned black/brown tabby Siberian cats as "golden" to describe their brighter background colour rather than their genetic heritage. That makes for problems if such a cat is transferred to a registry that understands golden to be related to silver.
The Siberian is recognised in most colours and patterns, including colourpoints (Neva Masquerade), but not mink or Burmese colour restriction. The colours not recognised are chocolate/lilac, cinnamon/fawn, caramel/apricot in any pattern.
Some registries recognise the "golden series". This is not recognised as "golden" by Britain's GCCF (a very conservative cat fancy). Siberian "Golden Tabby (with or without white)," Golden Tortie Tabby (with or without white)," "Golden Shaded" etc are not viewed as a genetic colour, but as a colour expression of Brown Tabby due to wide agouti banding on the hair shafts which limits the black banding and gives a warmer, brighter tone. This means that Siberian cats registered as "golden" by FIFE or TICA are re-registered as brown tabby (etc) when transferred into GCCF.
In Persians, Exotics and British Shorthairs, golden results from two copies of the recessive inhibitor gene combined with the wide band gene. These cats' parents will both have silver somewhere in their ancestry. In Siberians, the Sunshine colour is also inherited recessively but seems not to be the recessive form of the inhibitor gene. It brightens the agouti (ticked) areas of the coat. There is a misconception that when a cat with a silver parent isn't silver, it must be golden by default. Because the "golden" Siberians don't change from black/blue to a golden colour, it is also not an Amber or Russet mutation.
There needs to be a way of describing the brighter tone of some Siberian cats without using the word "golden". Siberian breeders have asked for the term "Sunshine" to be recognised so that this gene (or effect, as it may need a combination of genes) can be discussed and traced in pedigrees without confusing it with the recessive inhibitor Golden. Sunshine resembles Amber, but has important difference: sunshine kittens are born with black, not pink, pawpads which allows them to be distinguished from cats with the inhibitor gene. Sunshine + silver inhibitor can result in so-called "bimetallic" Siberians.
A KURILEAN TALE
The exact origin of kurilian Bobtails isn't known. Some contend they come from are a distinct local mutation while others believe they resulted from a natural mix of cats with the Japanese Bobtail mutation (which is widespread across Asia) and Siberian cats. The Siberian has the golden-like "sunshine" effect that brightens the agouti (ticked) areas of the coat and is considered distinct from the recessive form of the inhibitor gene which produces golden when combined with wide band.
If the kurilian Bobtail has historically interbred with Siberian cats, then maybe some have the sunshine gene, resulting in cats being registered as "golden" and having impossible red progeny on pedigrees! At a stretch, sunshine might even be linked to the dark/black tail tip of red tabbies whose parents are (mis?)registered as "golden".
We haven't resolved the issue of the dark tail-tip, except that it may be a super-abundance of red pigment giving a colour so deep that it appears mahogany or blackish. But we've cast a shadow of doubt on some kurilian Bobtail registered colours and the existence of Russian gold i.e. the sunshine gene/effect.