Question of the Day – Why White Spots?

Another question from the splendid littlemiao:

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.

White Spotting

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.

A Quizlet

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?

About Oldcat

Engineer with Cats
This entry was posted in Calpurnia, Cats, Genetics and tagged , , . Bookmark the permalink.

27 Responses to Question of the Day – Why White Spots?

  1. minlit says:

    How much visual recognition do you think cats use to identify each other?

    Like

    • Oldcat says:

      I’m sure there is some – I’ve seen cats react differently to a cat with a cone, for example. But it isn’t the only way, since I’ve also seen a cat react badly to one just home from the vet with new smells on it.

      Cat vision is different than human, too, since it is optimized to pick up motion rather than static detail. You can see that by how they ‘lose’ a treat that quits moving until you point it out.

      Like

      • minlit says:

        So, in a feral colony of say, majority tabby cats, do you think they use other senses more than sight to identify each other?

        Thanks for introducing me to the term ‘buttons’ btw. I always wondered if there was a technical term for the pattern on Mr Stripey Pant’s undercarriage!

        Like

      • Oldcat says:

        I think they use smell to some extent, and body language and probably a whole set of motion and body-language related characteristics that we can’t detect because we don’t sense the world how they do.

        Like

  2. Am I allowed to reply to the Question of the Day blog with a question?

    I’ve always thought I was a white cat with black spots, but your posts have me thinking that I must be a black cat with white spots. Is that correct?

    Like

    • Oldcat says:

      Yes, you are a black cat that “failed” to develop the color over most of your body due to other genes. The thought of the mechanism is that in development a signal spreads from the area near the spimal column in the embryo to ‘turn on’ the pigment producing ‘factory’ in each cell. If a cell doesn’t get the message before it is ‘too late’, it and its decendants will remain uncolored. The ones that do get the message produce color – which in your case is black.

      The ‘spread’ theory is to explain why the bottom and feet are affected first for the most part.

      Like

    • Oldcat says:

      Oh and the more questions the better. Putting them in a Q post would make it more likely that others with the same interest would see it.

      Like

  3. minlit says:

    “Calpurnia would never be interested in a “failed” black cat, would she?

    I think I prefer my human’s explanation. She says I’m “semi-formal” – not quite a tuxedo.”…

    :)I wish you could like comments here like on FB!

    Like

  4. Lurkertype says:

    As someone who lives with a Tux, who had a Tux mom and a Cowkitty dad (#6), thanks for this. I had the opportunity to observe several generations of the family, and they showed everything from 3-8.

    My Tortie girl has a locket, a splotch down the middle of her tummy, and 3.5 white paws. Her sister was a calico with mostly white.

    Like

    • Oldcat says:

      Its tempting to think that the difference between the common Tux level and the reasonably common Cow Kitty level is a double dose of white spotting in the Cow case, given average ‘volume’ in the polygenes.

      If you never saw a non White Spotted kitten out of the pair, it would fit this theory that Dad only has S to give, and all his kittens would be spotted too. If both were S/s, a quarter of the kittens would have no spotting.

      Like

      • Lurkertype says:

        I’m thinking back (it’s been a while) and all of the kittens had at least some white. It might just be paws and lockets, but they did mostly tend to cowkitties. TK’s sister was also a tux, and his brother was like Pedro, as was his uncle and cousins.

        All the ferals were finally either fixed or rehomed, so we don’t have swarms of them any more.

        Like

  5. littlemiao says:

    Thank you for another fascinating excursion into kitty genetics. This helps me understand my brother’s tuxedo kittens and also Dalek, their orange brother who has white paws and a white collar, so it looks like he wanted to wear a tuxedo but got the wrong color. Also, his tabby stripes don’t circle around him like normal stripes, they are long and parallel to his spine.

    I love the names for coloring patterns. Lockets and buttons… Ping has a mask and mantle. That is so mysterious-sounding. Sprocket must be a bicolor with extra with splotches.

    I wish I could figure out the quizlet!

    Like

    • Oldcat says:

      Here’s a hint – the two kittens have to be girl kittens. Not just any kittens will do, two specific kind of girl kittens.

      Like

      • littlemiao says:

        I still haven’t figured it out, but I haven’t quite given up yet. So if a kitty has the O gene for orange, they don’t have the B gene for black?

        I love Dalek’s retro tux!

        Like

      • Oldcat says:

        They still have Black, it is just that its effect is cancelled by the Orange gene – but only if the Orange gene is the ‘O’ variant. The ‘o’ version does not cancel Black. So seeing Black tells you something about the Orange gene – that it is ‘o’.

        So you have to be able to identify enough genes at one location in the kittens to fill in the mom and dad’s possible donations, and have one left over to ‘prove’ a second dad cat had to be involved.

        Like

      • littlemiao says:

        Okay… So, a orange girl-kitten and a tortie kitten would indicate that there must be two fathers, because if there is one orange girl kitten, it means it had to be O/O, but a tortie/calico can only occur with O/o, so that would mean there must be one O-dominant father and one little-o father. Is that right?

        And does that mean that different coat lengths in the same litter don’t indicate two fathers?

        Like

    • Lurkertype says:

      Dalek is retro. He is wearing a tuxedo from the 70’s, when they came in bright colors.

      Like

    • Oldcat says:

      I was responding here but it got too long so it will be in a QotD post instead tonight!
      Great job on the Quizlet!.

      Like

  6. Pingback: Question of the Day, and Answers | ThreeCatYard

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