Our Tonkinese are color coordinated with three coat patterns. The color varies with
intensity but is essentially the same color. The coat pattern gene is independent
and different from the two color genes. We get twelve color/coat pattern
combinations, three coat patterns for each of the four colors.
There is a major difference between the gene that determines the coat pattern and
the two that determine color. Each of the two color genes has one allele that is
dominant and one that is recessive. In the Tonkinese breed, the two alleles of
the coat pattern gene, neither are dominant over the other, but are codominant
to each other. Codominance means that the effects of both alleles will be visible
in cats that inherit the dissimilar pair of alleles together. Also, the
combination of those effects will cause the cat to look quite different from
cats that inherit two identical copies of the same coat pattern allele.
The two alleles that determine coat pattern in the Tonkinese breed are cs (the
allele for the Siamese coat pattern) and cb (the allele for the Burmese coat
pattern). Both alleles are from the albino series, a group of many different
alleles that all cause unstable pigment coloration. The instability is temperature
sensitive. This results in greater coloration on the cool part of the feline body,
or the points (the extremities). The torso has a lighter coloration because body
temperature is higher there. The amount of contrast between the extremities and
the torso varies from a very strong contrast in the Siamese coat pattern cscs
to a very weak contrast in the Burmese coat pattern cbcb. When we have a
Tonkinese with both cs and a cb (remember genes come in pairs - one from each
parent), we get a third variation which we call a mink cscb. Because neither
is dominant over other, they codominate. We achieve a coat pattern part way
between the other two in terms of contrast. Neither side wins.
Genetically, the allele that produces a truly solid colored coat is given the symbol
C and it is dominant over cs and cb. The C allele results in stable pigmentation
and the color does not vary based on temperature. This gene is not present within
the Tonkinese breed. cs and cb allele are recessive to the dominant C, while they
are codominant to each other.
Many people get confused when trying to determine the color/coat pattern of a
Tonkinese. They will describe the cat as dark. Dark in what way? The key is to
look first at the extremities for color and then second at the body for amount
of contrast to those extremities to determine the coat pattern. Again it is
intensity that is changing - not color.
Unfortunately, a further source of confusion is created by the names of the three
patterns: Point for the Siamese Coat Pattern, Solid for the Burmese Coat Pattern,
and Mink for the in-between Coat Pattern. All of the Coat Patterns have points
which are darker than the body and none of them is solid. The amount of contrast
varies for each color, with Champagne having the most contrast and blue the least.
A Blue Mink may have about the same contrast as a Champagne Solid. A Natural or
Blue Solid adult may appear solid even though it contains no C allele. When
looking at a young Natural kitten or a Champagne Solid adult, it is apparent
that they are not solid - meaning that the color is not distributed evenly over
the body surface and throughout the fur. However this contrast is small in
comparision to a point.
| Color/Coat Pattern Names |
| Natural Point |
Natural Mink |
Natural Solid |
| Blue Point |
Blue Mink |
Blue Solid |
| Champagne Point |
Champagne Mink |
Champagne Solid |
| Platinum Point |
Platinum Mink |
Platinum Solid |
Tonkinese darken with age. They are born without any point color; the latter
starts to develop within a few days. It is fun to see the mask (dark area on the
face) start small around the eyes and grow to cover the whole face. The entire cat
then darkens very slowly over the years. The paws pads start such that they look
like they have walked in ink and it increases to cover the whole paw. The eye color
is blue at birth and starts to change at around six weeks. It can continue to
change for many months. Because coat color is lightened by high body temperatures
and darkened by lower temperatures, the color can be altered by a bandage
covering the fur, illness, cold weather, or the reproductive cycle of a female.
Currently, only Minks can be shown for Championship status in CFA. Other
associations allow all three coat Patterns to be shown. One thing that cannot be
stressed too much is that these are all Tonks and, regardless of the coat pattern,
share the same standard for body type and the same personality. The only other
characteristic described in the Tonkinese standard that is affected by coat
pattern is eye color. Normally Points have blue eyes, Minks have aqua eyes,
and Solids have green/gold eyes. This is due to the differing effects of body
temperature on pigment in the eye; the effects of temperature on eye pigmentation
are different depending on which pattern alleles are inherited.
We will always have three coat patterns and can not 'breed out' the two patterns
of Points and Solids. It requires a cs and cb to make a Mink: when you mate a mink
to a mink you will always get a mix of coat patterns in the resulting litter.
Probability tables
What happens when you mate Tonkinese cats that differ in their coat patterns? The following shows the probability table for each combination.
Mating Coat Pattern Probabilities for Kittens
| |
Point cscs |
Mink cscb |
Solid cbcb |
| Point cscs |
Point |
Point 1/2
Mink 1/2 |
Mink |
| Mink cscb |
Point 1/2
Mink 1/2 |
Point 1/4
Mink 1/2
Solid 1/4 |
Solid 1/2
Mink 1/2 |
| Solid cbcb |
Mink |
Solid 1/2
Mink 1/2 |
Solid |
The same caveats apply to these probability tables as to the previous ones.
They tell you in some cases what you can't get, but how many of each type you
will get in a specific breeding are left to the fates.
Normally you want to pick cats to mate that have been proven in the show ring to
be good specimens of their breed. The irony of Tonkinese genetics is that because
a Point to a Solid breeding creates all minks, you get a higher percentage of
kittens that are eligible to be shown. Many of our Distinguished Merit (DM) cats
were never shown themselves.
