Author Lani Ritchey
CALIFORNIA CHINS
The Many Coats Of Patterns
Color patterns are not influenced by
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. Coat Color
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. Coat texture and/or length
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. Nudity (hairlessness)
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Coat colors
E
volution has provided a huge range of colors for livestock and plant
breeders to manipulate. In some livestock breeds, the color and / or color
patterns are not selected for since they have nothing to do with
performance. Holstein dairy cows are not selected for their black and white
( or white and black) color patterns. After all color patterns have nothing to do with milking and calving performance. However ,they do need to be
some version of black and white to be registered as a Holstein.
In some livestock breeds, coat color and patterns are absolutely essential to
the breed standard. In many dog, cat , rabbit and horse breeds only certain
colors and/ or color patterns are allowed.The breed standards can be so
specific as to what eye colors are permitted, where the white can be and
what type of coat texture and length is allowed.
Pleiotropic genes have a dual effect or more than one type of phenotypic
expression. There are several well-known lethal colors or color patterns-
white colors/patterns and roan patterns in horses, yellow color in mice,
platinum color in mink, a lethal color pattern in Rhodesian Ridgeback dogs,
and the sapphire color in mink and nine other species.
Lethal color problems start in the embryonic stage. Pigment cells are
formed at the early embryonic state when other neurological and body cells
are being formed at the embryonic midline Possibility of linkage to certain
genes controling the gastrointestinal development may be the explanation for
the lethal white in horses. The foals are born with nonfunctional intestines.
There are other problems associated with "white" animals. The Dalmatian
dog has a high incidence of deafness in the breed and white cats with blue
eyes are also deaf. The lethal white problem is not that uncommon- the
raccoon dog ,mink , and fox also have a lethal homozygous white and
deafness.
Coat texture and length
Coat texture refers to the rex, satin, curly, smooth/rough and woolly hair/fur
types. In this category are the double /single coat characteristics. It is
rather odd that the chinchilla has never had the usual mutations for coat
texture and lengths. Most domesticated rodent species have a wide range of
coat lengths and textures to go with the large variety of colors and color
patterns. This will be a problem for people wanting to spin chinchilla fur
into luxury wool products. However, coat length and textures do not affect
color patterns. There are many variations of the Himalayan (Siamese
coloring) color pattern in cats- the Himalayan color point Persian is a
double- coated long -haired version, the Siamese is a short coated version
and the Balinese cat is a long smooth coated version.The Himalayan color
pattern is instantly recognizable no matter what the coat texture or length is.
Hairlessness (Nudity)
The lack of hair or fur doesn't stop a color pattern from being visible. Man
has bred several species of mammals that are missing hair/fur. The Chinese
Crested dog has hair running down from the top of the head to the end of
the tail with lovely colored skin. In the Sphynx cat , all colors and color
patterns found in cats are permitted. The Sphynx are allowed peach fuzz on
tails and ears. Older animals will have more fuzz on them than kittens.
There are hairless versions of rats, mice, rabbits, and guinea pigs. Most hairless animals
are used in laboratory situations as it is easy to see side effects of drugs
and
other chemicals on naked skin.
There is a featherless chicken strain. It didn't "make" commercial as
featherless chicken took too much feed and warmth to get weight on. As a
laboratory animal, it is useful.
Color patterns
There are several color patterns common to a lot of mammals. Evolution is
very conservative and the modes of inheritance don't change rapidly or
very often. Chinchillas exhibit several coat color patterns and should exhibit
others but for some reason, they don't :
. agouti - the most common pattern in cats, dogs, rodents, and rabbits.
The 3 bars of color on one hair/fur shaft is commonly considered to be the
"wild color" or "standard". The Abyssinian cat, the Chinchilla rabbit, the
Syrian Golden hamster and the" standard "chinchilla chinchilla are example of
the agouti pattern. The Abyssinian cat is bred with multiple bandings to give
more warmth and clarity of color Wild-type allele "AA or Aa" gives you the
agouti color pattern. The "A " allele has apparently been bred out of
domestic horses. Cats have four agouti patterns -ticked (as in Abyssinian),
mackerel (herring
bone pattern), classic ( bullseye), and spotted ( Occicats or the jungle
wild cat pattern with or without rosettes).
. nonagouti - yes, this is a color pattern mutation. It is a solid colored (
or "self") hair/fur shaft. The term "self" refers to a single color . The
ebony color in chinchillas should be correctly referred to as an "ebony self"
. Allelic pair "aa" is the nonagouti color pattern and is recessive to the
wild "standard"
. albino -red/pink eyes- the skin/fur pigment cells are present but
nonfunctional. Albinism is caused by the blockage of an enzyme essential for
the formation of the pigment melanin. The wild-type allele "C" permits color
expression and the allele "c" prevents color expression. The "cc"
constitution is said to be epistatic to other color genes. The "cc" in its
homozygous condition "stand on" or blots out the expression of other genes
concerning coat color. Since it masks any color or color pattern genes present
on other alleles, the albino gene is considered to be more than a color gene
and something closer to a color pattern gene.
. Himalayan - albino, with black extremities, also called acromelanic
white . There is black on the nose, ears, lower legs, and tail with either
dark or blue eyes. It is a variation of the "C" series The interesting thing
about the Himalayan color pattern is body temperature influences the location
of the color. If you shave the hair off a section of the light colored hair or
put ice on the area for several hours, the pigment cells will eventually
produce dark colored hair. This can be a serious problem in show animals. The
Himalayan
color pattern in cats is referred to as the Siamese color pattern as the
color pattern was first found in the breed of cats that would become the
Siamese cat. (I don't know where the reference to Himalayan comes in because
Thailand (Siam) does not border on
the Himalayan mountains !!) "Pointed "cat breeds are available in over 90
different colors and color patterns. ( Remember color patterns
can overlap other color patterns- think crazy quilt patterns)
. Roan - two color patterns create the roan pattern. The roan color pattern
is formed by the progressive white spotting gene and the agouti gene. There
is a lethal roan factor in horses. Probably the lethal white gene is the
cause of death rather than the agouti series
("A"series). Recently cats have developed (or it has been recognized)
a roan gene. Some cats in Texas have developed a color pattern similar to
roan. The genetic testing experiments and positive identification are
still pending.
. Piebald - progressive white spotting color pattern- has several
variations in many mammal species.There are certain characteristics
color patterns that help define which one you are dealing with.
. White Band - a dominant pattern factor creates
a white band completely or nearly complete
encircling the trunk. Any colors can be white banded.
This color pattern is not found in cats but can be found in
hogs, dairy cattle, hamsters ,rats and mice.
. Dutch White Spotting- both primary major and
secondary minor genes are involved in
the inheritance. The current theory is 3 major
alleles are involved- 1 dominant and 2 recessive.
The markings must be symmetrical. The head patches
circling the eyes must be of similar size and not touch
the whiskers. The forehead blaze is determined by the shape of the head
patches. The separation between the white forepart and the colored rear
part must form as
straight a line as possible and be approximately at the center of the
trunk. The white part should include the front legs, extend around the
throat and cover the shoulders.
The rear toes are white with the rest of the leg colored.
The Dutch rabbit breed demonstrates this color pattern. It is very
difficult to breed the perfect Dutch markings. This color pattern is found
only in rabbits (or rabbit breeders were the only ones crazy enough to try
and breed this pattern !)
. English White Spotting- a dominant gene is found in mice,rats,and
several breeds of rabbits. Perhaps the most unusual rabbit breed with the
English White Spotting gene is the Hotot.The ideal Hotot is pure white
except for a black ring around the eyes. The ring is no wider than a
mascara drawn line ! The Hotot 's eyes are usually brown but blue or mosaic
eyes maybe seen. The odd colored eyes phenotype is called heterochromy.
. Asymmetric White Spotting patterns- in horses and quite
a few other mammals have a wide variety of names -
Variegated (mice), Broken -marked (mice), tobiano,
sabino, splashed white, piebald, and skewbald (horses).
The ideal Broken-marked mouse must have a single spot or nose patch on
either side of the head. The spots must be even in size and well dispersed
over the entire body.
The Variegated mouse is white with small splashes of pigment. The
problem with this color pattern is the tendency for the pigment to clump
around the head and rump. The third variation of spotting is the
Even-marked.
The spots are supposed to be distributed equally on either side of the
body. These mice may be born in to Broken- marked litters. There is an odd
color pattern in mice called the Black-eyed white. All color has been bred
out of it except for black pigment in the eyes. When bred to
self-colored mice, a variegated color pattern appears.
The tobiano pattern in horses in the main U.S. paint horse pattern. The
eyes are generally not blue , the lower legs are generally white and the
face markings are the traditional ones of the solid-colored horses-
blaze,snip,star, etc. The white may cross the top midline.The expression
of the color pattern can range from nearly solid -colored to nearly white.
The overo and the tobiano patterns look very similar but there are
definite differences, especially in breeding healthy foals.The overo
pattern has solid-colored legs, the white usually doesn't cross the top
midline and is usually irregular,scattered, splashy or calico. The face
markings are distinctive, bald-faced(all white), apron- faced( from forehead
down and around the lower jaw) or bonnet-faced (covers the ears,back of
neck and forehead ) and the eyes maybe blue or mosaic colored. The
amount of white can vary from almost solid-colored to nearly white.
To confuse the issue, there are individuals that combine the
characteristics of both color patterns ,which leads to problems in the
foaling barn. Tovero is the term used to cover these mixed patterned
individuals. Another confusing color pattern in horses is sabino.The
white ranges from a solid-colored body with high white stockings on the
leg. The head maybe extensively white except for the tips of the ears and
edges of the lips. The most common breed sporting a variation of this
pattern is the Clydesdale horse. The Splashed White usually has blue
eyes, all four legs are white, the head is white and most of the belly too.
It is possible that the same mechanism that produces the Viennese White is
at work with the blue-eyed horses.
. Harlequin or brindling - is found in many species-cats, dogs, foxes and
rabbits. The Harlequin rabbit has extremely strict color pattern
requirements. Tortoise-shell cats with their alternating red-black with the
brindle pattern is a classic example of midline division of pigment cells. A
well-marked tortoise -shell cat or Harlequin rabbit looks as if someone drew
a straight line dividing the color.
. Viennese White or the blue-eyed white is found in cats,dogs, and horses.
The animal may be pure white with blue eyes. Other color patterns can
occur with the blue-eyed white as they are independent of other color pattern
alleles. In cats, white is consideredto be an overcoat and the cats can be
genetically a tabby, particolor( white with color) or pointed (Himalayan)
underneath. Deafness occurs when the cat is homozygous white or particolor
pattern has extensive white over the head. (Remember the embryonic development
of
nerve cells and pigment cells ?)
The symmetrical patterns of white doesn't really apply to chinchillas. Or at
least I have not seen any examples of this. The one breed most people
would recognize is the Appaloosa horse. The Appaloosa breeders recognize
six varieties of patterns -frost, leopard, varnished roan (marble), white
blanket,spotted blanket and snowflake. The leopard pattern when on an
extensive white background resembles the Dalmatian dog's pattern .
The snowflake is a strange pattern. It can take years to develop or it can
disappear over time leaving you with a solid-colored horse. The Appaloosa
breed is also characterized by striped hooves, mottled skin , spots that are
raised above the main body color and they have "whites of the eye" irises.
The color patterns can take several years to fully develop (or disappear).
Fur bearing animals
In the fur-bearing animals, the nutria exhibits the same phenotype as in
rabbits for silvering. Silvering is caused by the depigmentation of the guard
hairs. The nutria also have a blue-eyed white color pattern. The piebald
pattern in nutria is called White Mark with spots on the belly fur and on the
skin on the paws. The gene symbols used for nutria are nonstandard as they
are German,Polish and Russian and there is a great deal of confusion on the
genetics.
Mink also have similar color patterns . The Hedlund white in the
homozygous state is completely deaf and usually has blue eyes
(remember blue-eyed white cats and Dalmatians ?). The sapphire disease
or Chediak-Higashi-like syndrone was first recorded in mink. Since then
the disease has been found in 9 other mammal species.
In the color pattern,Black Cross , the pattern is a thick black cross that
goes
from head to tail and on either side of the shoulders. In the Colmira , the
white markings are on the belly, breast, chin and head, and sometimes on the
feet and tail. This color pattern has a few neurological disorders associated
with it. TheFinnjaguar is mostly white with asymmetrical black spots and
mostly black tail. When bred to other color combinations, a calico color
combination can occur.
The various fox species also have color pattern mutations. As in the mink,
there is a variety of cross patterned colors. The red fox's traditional
coloration is a color pattern already. The color designated pearl in fox has
the same disorder,Chediak-Higashi syndrone, as the sapphire mink does.
This disease is found in humans, mink, cattle, mice, killer whales, cats, and
the Norwegian blue fox mutant, arctic blue . The white face color pattern
may have two blue eyes , mosaic eyes or one of each color. The amount of
white varies from minute white marking to a full blaze down the face and
large white collars. The homozygous state is lethal A Polish version ofWhite
face occured . It closely resembles the Dutch markings. It too seems to
have a lethal homozygous state. The various Platinum patterns vary only
in the intensity of the fur color and eye colors. The eyes may be brown
,blue or partly blue. And once again, the homozygous is lethal. The arctic
marble and arctic marble white fox color patterns are mostly white animals
with touches of color. The arctic marble has a white blaze with colored
areas around the eyes,on the forehead and ears and a dark stripe down the
topline. The colored area can spread over the shoulders leaving the legs,
belly and most of the body white. The arctic marble white fox 's coloration
resembles the van pattern in cats. Just the barest touch of color appears on
the ear edges, forehead and along the back and tail root. The shadow
,shadow white , Jotun, and sognlibles phenotypes are the main color
pattern mutations in the blue fox. The white markings are similar to white
face and platinum mutations in the red fox. Again the eyes may be
heterochromic and there is a homozygous lethal.
Some other color / color patterns found in both fur animals and companion
animals ( for that matter, humans) is the silvering polygenes. It is thought
two genes or polygenes control the amount of depigmentation that occurs.
Silvering is caused by the lost of pigment on the hair/fur shaft. Depending
on the amount of depigmentation, the color pattern can be silver, shaded or
smoke. Silver is 1/4 color at the tip and 3/4 depigmented hair/fur shaft.
Shaded is 1/3 to 1/3 color at the tip and 2/3 to 1/2 depigmented hair/fur
shaft.
Smoke , the most difficult to achieve is 3/4 tipped and 1/4 depigmented.
The silvering affect is the same for humans. As our hair silvers with age, we
go from shaded to silver. It is nice to know the same mechanism works for
us as it does in mink,fox, dogs, cats and the silver-dapple color in Shetland
ponies.
As you can see, evolution is very conservative with its colors and color
patterns. Unfortumately the same health problems also occur in the same
colors. The sapphire color in the several species is linked to an
autoimmune disorder. There is a universal problem with a homozygous
lethal white. Blue eyes or blue and brown eyes (heterochromic) seem to be
linked to white coats. Harlequin animals demonstrate the embyronic
topline cellular division. By studying the work done in other species,
it should be possible to manipulate the colors and color patterns in your
breed/species better.
References and suggested reading material
McNitt, James I, Ph.D., RABBIT PRODUCTION, 7th Edition , Interstate
Publishers,Inc. 1996
Nes, Norodd, BEAUTIFUL FUR ANIMALS AND THEIR COLOR GENETICS,
SCIENTIFUR 1988
Pfarr, Richard, MICE AS A NEW PET, T.F.H. Publications 1991
Roberts, Mervin F. , HAMSTERS A COMPLETE INTRODUCTION, T.F.H.
Publications, 1987
Sponenberg, D. Phillip, HORSE COLOR A COMPLETE GUIDE TO HORSE COAT
COLORS, Breakthrough Publications 1983
Suzuki,David T. , AN INTRODUCTION TO GENETIC ANALYSIS ,3rd edition,
W.H. Freeman and Company 1986
Vriends-Parent, Lucia, THE NEW RABBIT HANDBOOK ,Barron's Educational
Series,Inc. 1989
REGISTERING YOUR AMERICAN PAINT HORSE, American Paint Horse
Association
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