Maybe one day you can explain why some kitties are tuxedo kitties (I’m thinking of my brother’s calico/tortie mama + the b&w cowkitty papa, who had 2 boy tuxkits).
Today’s the day!
In cats white is not a pigment, but is what happens when the other means of laying pigment on a hair are blocked out. Some of these cause a totally white cat, others just produce a cat “with white”. These can appear on any color or patterned cat, as you can see with Calpurnia, a “Seal Point with White”.
Buttons and Lockets
Before we move on to true White Spotting, there is another kind of spotting – these produce one or a few white spots on the midline of the belly or on the chest. The genetics of these is not well-known – but cats that have a lot of them tend to have kittens with them and those without, without. The ones on the stomach are called “buttons” and the ones on the chest are called “lockets”. They are pretty common – all my cats without white spotting have had at least one of them.
True White Spotting in controlled by a gene, called (oddly enough) White Spotting. There are two options – S, which activates spotting, and s, which does not. One S is enough to produce some spotting, and the thought is that a double dose (S/S) produces more spotting than only one.
The effects of white spotting produce spots first on the feet, then generally up the legs and on the stomach, spreading up the chest and face. Then it moves up the sides until the head, back, and tail separate. Even higher levels result in isolated white islands up until you have a totally white cat.
Some levels have been given names – like the Tuxedo and Van. The Tux is 4 white paws, white on the centerline of the belly and on the chest, and usually up to the chin and possibly a blaze on the face. The back of the neck is still black, and most of the sides and back and the tail. The Van is white except for the ears, top of the head and tail.
What controls the level? Well, they don’t know, except that it isn’t simple. Other genes, and more than one, probably do the job – they call it polygenes. Again, breeders can select on ‘lots of white’ and ‘little white’ to some extent. And it is possible, but not likely, for the polygenes to be so low that no spots result even with an S gene.
I think of the Spotting Gene like the on/off switch of a stereo and the polygenes as a volume control knob.
There is one other interesting relationship when a Tortie cat (one with both black and orange color) also has white spotting. As the amount of spotting grows, the size and distinctness of the colored regions grows larger as well. A tortie without spotting has small and well mixed color regions, whereas a Calico has few, large, and distinct color regions.
In littlemiao’s brothers case, each parent had at least one S gene to contribute to a kitten. And the polygenes resulted in the relatively common Tux level of spotting.
It is possible for a mama cat to have kittens from multiple fathers in one litter. I was wondering how common it is, and if you could prove from a set of kittens that they have different fathers. For a while I thought it was not possible without knowing something about the parents, but then I came up with a way with just 2 kittens from a litter you could show that they had different fathers. Anyone want to try and figure it out?