There is a lot of confusion about tri-colored cats. This FAQ is meant to clear up some of the confusion, explain what is and what is not a tri-colored cat, and how a true tri-color occurs.

Table of Contents

• Are you going to throw a lot of jargon at me?


• OK, So what do you mean by a true Tri-color?


• Is it true that only females can be true Tri-colors?


• OK, so there's a reason. Why?


• Oh, man. I knew this was going to get complicated!




• Basic sex inheritance


• The red or orange gene


• Males and the O gene


• Females and the O gene


• So how come there are some male true Tri-colors?


• So male Tri-colors are rare. Can I sell one for big bucks?


• What is the difference between a Calico and a Tortoiseshell? And what in heck is a Torbie?


• What are the possible color combinations?




• Why not?




• Can you wrap this up?


• So why didn't you just say so in the first place?

Are you going to throw a lot of jargon at me?

Well, I'm going to try not to. I believe in Plain English.

OK, So what do you mean by a true Tri-color?

Many cats appear to have three colors, but are not true tri-colors. A true tri-color must have one of its colors derived from the red gene -- either red (orange) or cream (kind of a light, orangey beige, not unlike the color many people call "ginger"). If it does not have one of these two colors, it is not a true tri-color. The second color must be white, and the third color must be black, blue (a blue-gray), chocolate, lilac (a pale rose-beige), cinnamon, or fawn (a pale buff color). Black and blue are by far the most common.

Some cats may appear to have three colors, but in fact may only have two. There is a designation called "bi-color" where the cat has a significant portion of white fur, but the rest of the cat is either a solid color such as black, blue, red, or a patterned color such as brown tabby, silver tabby (what many people call "tiger", blue tabby, etc.

A white cat with patches of tiger stripe might appear to have three colors -- white, black, and gray -- but because one of the three colors is not red or cream, it is not a true tri-color. It's defined (color wise) as a tabby and white. A white cat with red or cream tabby patches is not a true tri-color either; only one of the colors may be red or cream in a true tri-color.

In some rare cases, a Siamese-type pointed cat may appear to be a tri-color because of white patches on its body. These cats are mixed-breed, as significant white spotting is not found in the Siamese breed (although some small bits like a little white spot on the toes is found; this is considered a disqualification for showing). In this case, the cat is not a true tri-color either -- it's a seal point and white, or a blue point and white, or a chocolate point and white. The only exception to this is found in breeds such as the Himalayan, Colorpoint Shorthair and Javanese, which allows the points themselves to be tri-colored (what are called "tortie points"). But that's a
whole other story. On a pointed cat, if the points themselves do not include
three colors -- white, red or cream, and one other color -- it is not a true tri-color.

OK, so there's a reason. Why?

It's the nature of the genetics. 

Oh, man. I knew this was going to get complicated!

No, wait! Don't go yet! It's really not that confusing. Just read. I'll keep it simple.

Basic sex inheritance (boy, the word "sex" always gets people's attention!)
Cats (along with humans, dogs, armadillos, weasels, mice, and other creatures) have two sex chromosomes. Chromosomes are the vehicles for genes, and genes define traits like coat color, fur length, eye color -- everything that makes the cat what it is.

Sex chromosomes define gender. There are two sex chromosomes (stands to reason, what?), designated X and Y. Each parent contributes one sex chromosome, and these determine the gender of offspring. Females produce only X chromosomes in the form of their egg, but males produce both X and Y chromosomes, propelled in sperm. It's the male's contribution that determines whether an offspring is male or female (if only Henry VIII had known . . .).

Females produce eggs: X X

Males produce sperm:  X Y

These eggs and sperm also carry one half of the parent's genetic material, which explains inheritance. Eggs and sperm do not carry the same combination of genes, which explains why all of our offspring don't look identical to one another.

When egg and sperm meet, they combine their traits to form a single entity, not unlike pulling two halves of a zipper together. They also combine their sex chromosomes.

If an X sperm meets the X egg, they produce an XX, or a female.

If a Y sperm meets the X egg, they produce an XY, or a male.

Since there is no such thing as a Y egg, no YY is possible.)

So what does this have to do with Tri-colored cats?

I'm getting to that.

The red or orange gene

Unlike other coat color genes, the gene that determines red coloration can be carried only on the X chromosome. If you look at pictures of chromosomes (they look a bit like X-shaped breakfast cereal, with long arms), you will see that the X chromosome is normal sized in relation to other things, but the Y chromosome is smaller. It can't carry the gene that determines red color; only the X chromosome can do that.

The gene that determines red or orange coloration in cats is designated as O (for orange).

• O = orange


• o = non-orange

If the cat inherits an O pattern proper for its gender (I'll explain that in the following sections), the cat will be red or orange (I'll just continue to call it orange, even though most cat associations refer to this as red). This orange will cover up all other colors, except pure white. If the cat inherits an o pattern proper for its gender, it won't be orange.

Males and the O gene

Remember, however, that the Y gene can't carry the O gene at all -- only X can. Males are genetically XY. The Y fires a blank as far as the O gene is concerned, so males only get one O gene -- from Mom. The
designation for this "blank" is usually just written as Y.

Male patterns:

• OY = orange cat


• oY = non-orange cat

These are the only possibilities for an XY cat.

Females and the O gene
Females get one X from each parent, so they get two O genes. However, here's where things get exciting. In most genes, the capital letter designation is
for dominant genes, and the small letter designation is for recessive genes. In most genes, if the cat gets one dominant gene and one recessive gene, whatever
is the dominant gene will show up and the recessive gene won't actually appear on the cat. The cat is said to "carry" the recessive gene, which means
s/he can pass it on to offspring. So by that rule, if the female cat gets one O and one o (Oo), she should be orange, right?

Not with this gene.

With the O gene, the O and o actually combine
their efforts, displaying both orange and non-orange, along with white.
This is called a mosaic. This creates the true tri-color -- the calico or
tortoiseshell. You must have the combination of the O and the o to create this,
which means the cat must have two genes. Since only Xs can carry the O gene, the
cat must have two X genes -- or in most cases, be a female.

Female patterns:

• 
  <il>OO = orange cat</il>
  <il>


• oo = non-orange cat</il>
  <il>

Oo = tri-colored cat</il>


So how come there are some male true
Tri-colors?

The answer: genetic misfire.

Sometimes, a male cat will get three sex
chromosomes instead of two. This is a genetic anomaly. Genetics is all about
pairs; you should only be able to have two of any genes, two of any chromosomes,
residing in any individual. Although in some cases there are more genes than two
possible for a given trait (like all the possible eye or hair colors on
people), only two traits can actually sit there. It's sort of like owning a Geo
Metro convertible: you might have more than two who want a ride, but you can
only fit two in it.

Well, sometimes, weird things happen in genetics,
and you get an extra gene or chromosome in there.

Sometimes, these duplications can have negative
effects. For example, Down syndrome in humans is caused by a duplication of
Chromosome 23, where there are three chromosomes instead of two. Animals are
only meant to have a certain number of chromosomes; in this case, having a
&quot;spare&quot; isn't good.

In cats (as well as other creatures, including
humans), sometimes there is an extra sex chromosome. Some can be invisible and
never detected.

A male cat who is a tri-color must have two X
chromosomes to carry the Oo pattern. Thus, the cat must be at least an XXY. In
humans, this pattern is known as Klinefelter's syndrome. One result of this
syndrome is that the male has trouble with developing secondary sex
characteristics and is usually sterile. However, unlike Klinefelter in human, an
XXY male cat will usually not have any outward signs of its genetic makeup,
unless it's a rare male tri-color.

Although a male tri-color almost certainly
sterile, you will still want to neuter such a cat to reduce such undesirable
traits such as spraying and aggression.

Only to the gullible. They are not considered
desirable in purebred breeding programs, as in some associations they cannot be
shown or be used in breeding programs. They won't breed more male tri-colors.
There is not a significant market for them. Best just to neuter him and keep him
as a beloved pet, or find him a good home.

Goodness, a lot of questions there.

The difference between a calico and a
tortoiseshell is this:

With a calico, there is a significant amount of
white, and the two colors are broken up into distinct patches. This has to do
with the interaction of white spotting.

With a tortoiseshell, the three colors are
blended and don't form distinct patches. A tortoiseshell may have significant
portions of white as well, but the remaining colors are blended (this particular
pattern is called a tortoiseshell and white).

A torbie, or patched tabby, is a tortoiseshell
where the tabby pattern is very distinct all over the cat. A calico or
tortoiseshell may have distinct tabby pattern on the red or cream patches (has
to do with another gene we won't get into at this juncture), but no patterning
on the other color. This isn't a torbie. A torbie is clearly patterned all over
the cat -- though never on the white.

What are the possible color
combinations?
 

• 
  First color is: white, always 


• Second color is: red or cream.


• Third color is: black, blue, chocolate, lilac,
  cinnamon, or fawn. Black and blue are by far the most common in domestic cat
  populations; chocolate is fairly rare, and cinnamon is almost unheard of. But
  they're worth mentioning. I'm not going to go into a lot of detail on the
  inheritance of black, blue, chocolate, lilac, cinnamon, and fawn. It's their
  relationship to the red gene that we're discussing in this FAQ. That's the
  subject of another FAQ.

These colors combine in very distinct ways. You
can't have a chocolate and cream, or a blue and red, or a black and cream.
Why not? The answer: the dilution gene.

There is a gene called the dilution gene which in
appearance &quot;washes out&quot; a color and makes it a lighter version. In
dominant form (DD or Dd), the cat is normal colored. In recessive form (dd) the
cat's color is diluted.

Color Normal   (DD or Dd)          
Diluted


black               
black                     
blue

chocolate         chocolate               
lilac or lavender

cinnamon       
  cinnamon               
fawn

red                  
red                         
cream

If the cat is diluted, all its colors are diluted. If the cat is not diluted, none of its colors are diluted.

So you can only have a certain number of possible combinations, based on the fact that you must have one color from each of the three, and you must have either all dilution or no dilution.

Just a note: tortoiseshells and their dilute counterparts may have very, very little white present. It's the combination of the red or cream with black, chocolate, or cinnamon that's important here.

CALICO OR TORTOISESHELL PATTERNS, UNDILUTED*

*patterns with black are just designated by pattern, not by color

calico (black, red, and white patches)

tortoiseshell (black, red and white mixed up)

chocolate calico/tortoiseshell (chocolate, red and white)

cinnamon calico/tortoiseshell (cinnamon, red, and white)

CALICO OR TORTOISESHELL PATTERNS, DILUTED*

*Dilute tortoiseshells are often referred to as (color) creams.

dilute calico (blue, cream, and white patches)

blue-cream (blue, cream, and white swirls)

lilac-cream or lilac calico (lilac, cream, and white)

fawn-cream or fawn calico (fawn, cream, and white)

TORBIE OR PATCHED TABBY PATTERNS, UNDILUTED

brown patched tabby (brown tabby, red, and white*)

*A brown tabby is genetically a black tabby

chocolate patched tabby (chocolate tabby, red, and white)

cinnamon patched tabby (cinnamon tabby, red, and white)

TORBIE OR PATCHED TABBY PATTERNS, DILUTED

blue patched tabby (blue tabby, cream, and white)

lilac patched tabby (lilac tabby, cream, and white)

fawn patched tabby (fawn tabby, cream, and white)

And of course, you can have any of these "and white" except for calico, which already has significant white spotting from the gene that causes the "and white".

Can you wrap this up?

Sure.

Cats who do not have one of the following combinations are not a true tri-color (although tortoiseshells and their dilute counterparts may have a negligible amount of white):

• Red, Black, White
  
• Red, Chocolate, White
  
• Red, Cinnamon, White
  
• Cream, Blue, White
  
• Cream, Lilac, White
  
• Cream, Fawn, White









So why didn't you just say so in the first place?





Because without the explanation, you probably wouldn't have believed me.





Torties, Calicos and Tri-color Cats FAQ
[link]
by Barbara French, e-mail: bcfnmp@ritvax.isc.rit.edu