COTA KENNEL

Colors and Coats of the Shih Tzu
After dogs began their association with humans and were transported into other areas and climates, their coat and pigments began to change thanks to the helping hand of Mother Nature – spontaneous genetic mutation brought us the myriad colors, patterns and coat varieties we enjoy today. Because of these mutations, our canine friends come in hundreds of color and pattern combinations. Humans also played a role in coloring outside the bloodlines through selective breeding.  While all of these choices are great for the dog lover who likes variety, they also can be confusing. 
Coat: You may not realize it, but there are several different types of hair that work together to create your dog's coat. The type of hair the dog has depends somewhat on his country of origin (tropical, arctic), original purpose (hunter, protector) and genetics. Types of Hair: Most breeds of dog have three different hair types: tactile hair, an outer coat and an undercoat. Tactile hairs are the sensory hairs and are primarily found as whiskers and stiff hairs on the eyebrows, chin and sides of the face. The outer coat is composed of guard hairs. This is also called the primary type of hair. These are long, smooth and stiff hairs that generally grow throughout the coat and naturally cover the undercoat. The undercoat is called the secondary coat and is made of short soft dense hair and primarily supports the outer coat. Length of Hair: The length of the hair is often connected to the area in which the dog was originally developed. Long haired dogs are typically associated with colder climates since the longer hair provides more insulation and warmth. Through selective breeding, the growth phase of the hair was prolonged, resulting in a longer coat. Long hair can be coarse or fine. Fine long haired dogs include poodles, shih-tzu’s, and shih-poo’s. These dogs have a higher number of secondary hairs than primary. Since secondary hairs stay in the follicle longer than other hair types, these breeds tend to shed less than others. Types of Coats:  In addition to coat lengths and hair types, there are also different types of coats. The type that includes Cota’s poodles, shih tzu’s, and shih-poo’s are as follows:  Curly Hair and Straight Hair: Through genetics and selective breeding, breeds with a naturally wavy coat have developed. In addition to having curly hair, the follicle is also curly. Examples include the poodle.
Pigmentation Color:  A dog's color depends upon the presence of pigmentation in the epidermis. For dogs, only two pigments exist: black-brown and yellow-red. All dogs, no matter what color they are on the outside, are genetically either black-brown or yellow-red. All other colors result from other genetic factors or modifiers acting on these two pigments. Pigments are produced in cells called melanocytes, and the distribution and number of these cells are determined by the dog's genetic makeup from the sire and dam. These cells pass the pigment onto the dog's hair, skin and eyes, and create the pattern and color. In addition, the melanocytes may not produce pigment during all stages of hair development, resulting in banding, agouti, ticking, etc. Three specific genes are essential to the dog's colorful exterior: pigment, color and density. The pigment gene determines the amount of pigment that's distributed over the dog's body. The color gene determines the intensity of the dog's color. The density gene determines the density of the pigmentation; the more densely packed the pigment, the darker the color will be. For example, in order to appear black, the dog must possess three genes: B for black pigmentation, D for dense coloration, and C for full color. These are all dominant genes. However, these genes have corresponding recessive mutations that can change the dog's appearance. Researchers have identified several mutations that occurred many years ago, when canines had only recently become so-called domestic animals. These mutations are not the only ones that affect color and pattern, but they are essential for the myriad color, pattern, and coat varieties we see in dogs today. They are as follows:  Dilute, which is recessive to dense coloration; this mutation creates a softer, paler version of a dominant color. For example, blue is the dilute of black, and cream is the dilute of red and liver is the dilute for brown.  Piebald spotting factor, which creates areas of white. This gene is incompletely dominant and is affected by modifying genes, which causes the white areas to vary greatly in size and location. Long hair is recessive to short hair.  All poodles, shih tzu’s and shih-poo’s have the recessive trait for long hair.  The short hair dominant gene was selectively bred out of the breeds.  A system of internationally recognized symbols was established to make it easier to understand the color genes and relationships to one another. Capital letters indicate dominant genes while lower case letters represent recessive genes. The Shih Tzu was almost lost forever, this most ancient of breeds was saved from extinction by some very dedicated breeders. The color inheritance is complex now, but as more and more animals are imported and the breed becomes more popular, new colors will appear from long forgotten or lost gene complexes.
Coat Colors-Black/Liver:  The most basic of all gene series is told by the color of the nose, lips, eye rims and foot pads. All dogs regardless of the actual coat color are Black, Brown, Red, or Yellow. Blue is recessive of Black, Liver is recessive of Brown, Cream is recessive of Red, and Gold is recessive of Yellow. A homozygous (having a double dose for that factor) recessive liver animal will have all black coat color produced by the action of other genes changed to liver. Basic eye color in all dogs range from the deepest black - brown to amber and blue, the recessive liver "points"(nose, lips, eye rims and foot pads) gene will lighten whatever eye color the dog have, thus a liver pointed animal cannot have the deepest brown- black eyes. Black is dominant but a heterozygous (a double gene - - one dominant factor, one recessive factor) animal carrying the recessive for liver will show a slight amount of incomplete dominance of the black over the liver. These dogs will show rustiness or burned look to coat at seasonal changes or hormone change time. These shadings have no pattern and come and go with coat changes, some only showing at birth. This rustiness is only obvious in black coat colored animal--not being noticed on Yellow-Reds, etc. Dilute: This strong recessive changes everything and is the only gene complex capable of changing the basic color of the "Points" gene list above. Point color on a dog can change with the action of sunshine, frostbite, injury, illness, stress or diet. You may have noticed that a dog's nose will "go pink" the day before a show. Some of these changes are temporary and some permanent. Usually if, say a nose has been damaged, lip, eye rim and pad color remain to determine the true genotype of point color.
A black "Points" gene dog with recessive (homozygous- having a double dose for that factor) dilute will have all black points changed to a slate or dark blue sometimes appearing to be a nice pewter color or gray (any shade of gray). It may also take on a purplish or lilac color in some dogs.  This coloration is so slight sometimes the animal only looks slightly "dusty" or it may have deep dark gray points or charcoal. If this is the case, they are still considered a blue dog by AKC standards.  If black patterns are present, they are also changed to blue--thus, blue mask, blue trace marks, blue tipping and blue brindling. Some blues may appear an Isabella color, being a dusty rose coat color or cream with a pale blue masking and shading….this is also out of the blue gene.  They may also have blue eyes.
A brown "Points" gene dog with recessive (homozygous- having a double dose for that factor) dilute will have all brown points changed to a liver, flesh, deep brown or chocolate color, or pinkish color for the points and a livered colored coat.  The coat color may be in varying shades of browns, reds, blondes, etc., but black is never an attribute. Linked to the dilute gene is a blazing eye color ranging from the lightest watery hazel- blue to flaming green. A dark eye cannot occur in the dilute animal.
This dilute series of genes is very prevalent in breeds coming down from the original "temple dogs."
Coat Colors-Yellow-Red (- includes Fawn, cream, red fawn, mahogany, gold, etc.) Two different types of yellow-red occur in the Shih Tzu. Both are recessive to pure all over black. The interaction of these two series of genes is complex and hard to understand. Black can be produced by breeding a dog from one type of yellow-red to a dog from the other yellow-red making it appear that the black is recessive is not. In this breeding, each series loses something allowing black to occur.Yellow-Red Dogs of this color can be born pure black and, when the hair grows, be a rich red color. Dogs can be born a creamy white and darken over. Black masks, black tipping, black trace marks, or possible black brindling. If a liver point gene is present, no black can occur--thus, liver masks, liver tippings and liver trace.
Coat Colors-Extension Yellow-Red This series is also present in the Shih Tzu. A dog is much more evenly colored or solid. He will not change much from birth. Extension Yellow-Red is a strong series. Extension animals will not show any signs of patterns--thus no masking, no tipping, no traces, or no brindling. Sometimes only by breeding can you tell which type of yellow-red occurs in your animal. A Yellow-Red dog from either series can either be black pointed or liver nose "pointed". The liver point gene does not change the color of the Yellow-Red. An example of this would be a solid blonde or red liver Shih Tzu.  Patterns will occur in Liver, however, instead of black, giving liver masking, tipping traces or brindling.
Color and Paling These two series of genes work somewhat together giving the multitude of shades in both types of Yellow-Reds listed before--also they give the shades of color in the pure, deep liver or chocolates. They do not affect pure black or pure white. In the Yellow-Reds, the color of the Shih Tzu can range from almost a pure white-cream to a dark red mahogany. In general--the lightest, palest colors are more recessive and the darker, clearer ones are most dominant. In the liver / chocolates, the color can range from beige to Hershey color.
Agouti Coloring (Wolf or Wild Coloration) A lovely gray banded coloration with silver trim which is found in the soft blue -silvers in the Shih-Tzu. This series allows full color in the points--so black and pure liver points remain with full eye color. Dogs are born with this coloration. All “pattern” genes show, thus, a blue with a black mask or black with blue brindle, or black overcoat with silver undercoat and liver ticking, with chocolate points can occur.  With liver points, a soft banded beige gray with liver patterns could occur. They are still registered by pigmentation only according to AKC standards don’t forget.
Patterns There is much disagreement with color geneticists as to just how these are inherited but all agree that dogs colored primarily from the Yellow-Red series produce these--thus Yellow-Reds, Agouti (wild ) animals can have these patterns. If an animal has both types of Yellow-Red, a small amount of pattern genes could show--mask just beyond the end of the muzzle or a slight "ghost brindling or ghost mask". Pure extension Yellow-Red will not have these patterns.
Black Mask Dominant and factored. Ranging from none to fully covering the whole head and ears, a mask gives expression to the face in the Shih Tzu. It gives much expression to eyes and accents ears. Too much masking in the breed however could be undesirable. If a liver point gene is present, masking will occur in liver color.
Black Tipping Black will tip and color tips of hair. Often found in blues when born. 
Brindled It comes down from lines of Extension Yellow-Red or Blacks as a true Yellow-Red cannot carry it without showing. Brindle needs a lovely base color to overlay which results with many degrees of tiger striping ranging from a few pencil lines to a zebra pattern. Agouti also makes a lovely base for brindle. Brindle is dominant and can occur with or without black masking, etc. If a liver point gene is present, all brindling will occur in liver over fawn or other colorations.
Definitions:  Allele: One of a pair of genes. Heterozygous: One member of a gene pair is chemically different that the other. Hence, the animal can pass a certain characteristic (determined by one gene) to one offspring through a sperm or egg cell and a different characteristic to another. Homozygous: both members of a pair of genes which the animal passes on to its progeny are the same. It cannot transmit any other specific characteristic than what it has to give.   

KNOWN COLORS OF SHIH TZU IN AMERICA 

Gold, Gold & White, Red, Red & White, Cream, or Cream & White: Includes Dark and Light Cream, Gold, or Red.  Cream’s are usually seen with shadings of apricot-gold on ears, hocks and dorsal stripe.  It is unusual for a cream to not have a dorsal stripe or to not have apricot-gold shading on ears.
Silver or Silver & White: This unusual color seems to be part of the cream gene pool. The dog casts a platinum silver shade, light like a cream but without the usual dorsal stripe. Some placed these in the category of dark skins creams.
Black or Black & White: Most blacks in this breed are shaded blacks...with shading of red, silver, brown or chocolate. True jet blacks are rarely seen in Shih Tzu. The coat is usually dull instead of shiny because of the dilute traits that they can carry.
Brindle or Brindle & White:  Brindle needs a lovely base color but comes with many degrees of tiger striping ranging from a few pencil lines to a zebra pattern. Agouti also makes a lovely base for brindle. Brindle is dominant and can occur with or without black masking, etc. If a liver point gene is present, all brindling will occur in liver over base colorations.
Dilute: Total lack of black pigment. Includes: (Cream with liver points), Light and Dark Liver-Chocolate (light milk chocolate to dark hershey brown), Lilac (a blue/chocolate giving the appearance of lavender found only in dilute) All of these have self- colored points- - nose, pads, eye rims, lighter eye)
Liver or Liver & White:  This is a recessive gene.  All Liver-Chocolate have liver-brown to red points.  They can have masks if solid or tips to brindling. 
Blue or Blue & White:  can range from very dark blue to a light silvery blue. Puppies are all usually lighter in color at birth if they are a “true” blue. Puppies are often, born with blue eyes at birth, but going darker with age. Nails are self colored. Isabella: A dusty rose color coat with blue masking on face and a blue dorsal stripe. It has darker blue points. Important: some Isabella's are born completely blue at birth with the only noticeable difference from their blue littermates is a fawn shading appearing on the top of the head. By 10 weeks or so, the change is dramatic from blue to Isabella. Part of the blue gene group. Lilac: Presently the rarest of all colors. It is a chocolaty- blue dilute color giving the appearance of purple. Always found in dilute only. Part of the blue gene group.

Basic GeneticsThe basis for order in life lies in a very large molecule called deoxyribonucleic acid, mercifully abbreviated to DNA. A related molecule, ribonucleic acid (RNA) provides the genetic material for some microbes, and also helps read the DNA to make proteins. DNA has a shape rather like a corkscrewed ladder. The "rungs" of the ladder are of four different types. The information in DNA comes in how those types are ordered along the molecule, just as the information in Morse code comes in how the dashes and dots are ordered. The information in three adjacent rungs is "read" by a kind of RNA that hooks onto a particular triad of rungs at one end and grabs a particular amino acid at the other. Special triads say "start here" and "end here" and mark off regions of the DNA molecule we call discrete genes. The eventual result is a chain of amino acids that makes up a protein, with each amino acid corresponding to a set of three rungs along the DNA molecule. There are also genes that tell the cell when to turn on or turn off another gene. The proteins produced may be structural or they may be enzymes that facilitate chemical reactions in the body.We now know that chromosomes are essentially DNA molecules. In an advanced (eukaryotic) cell, these chromosomes appear as threadlike structures packaged into a more or less central part of the cell, bound by a membrane and called the nucleus. What is more important is that the chromosomes in a body cell are arranged in pairs, one from the father and one from the mother. Further, the code for a particular protein is always on the same place on the same chromosome. This place, or location, is called a locus (plural loci.) There are generally a number of slightly different genes that code for forms of the same protein, and fit into the same locus. Each of these genes is called an allele. Each locus, then, will have one allele from the mother and one from the father.
How? When a dam or sire makes an egg or a sperm cell (gametes, collectively) the cells go through a special kind of division process, resulting in a gamete with only one copy of each chromosome. Unless two genes are very close together on the same chromosome, the selection of which allele winds up in a gamete is strictly random. Thus a dog that has one gene for black pigment and one for brown pigment may produce a gamete which has a gene for black pigment OR for brown pigment. If he's a male, 50% of the sperm cells he produces will be B (black) and 50% will be brown (b).When the sperm cell and an egg cell get together, a new cell is created which once again has two of each chromosome in the nucleus. This implies two alleles at each locus (or, in less technical terms, two copies of each gene, one derived from the mother and one from the father,) in the offspring. The new cell will divide repeatedly and eventually create an animal ready for birth, the offspring of the two parents. How does this combination of alleles affect the offspring? There are several ways alleles can interact. In the example above, we had two alleles, B for black and b for brown (liver). If the animal has two copies of B, it will be black. If it has one copy of B and one of b, it will be just as black. Finally, if it has two copies of b, it will be like a chocolate or Liver Shih Tzu. In this case we refer to B as dominant to b and b as recessive to B. True dominance implies that the dog with one B and one b cannot be distinguished from the dog with two B alleles. Now, what happens when two black dogs are bred together?We will use a diagram called a Punnett square.

For our first few examples, we will stick with the B locus, in which case there are two possibilities for sperm (which we write across the top) and two for eggs (which we write along the left side. Each cell then gets the sum of the alleles in the egg and the sperm. To start out with a very simple case, assume both sire and dam are black not carrying liver, that is, they each have two genes for black pigmentation. We then have:

All of the puppies are black pigmented  if both sire and dam are BB (pure for black).Now suppose the sire is pure for black but the dam carries a recessive gene for liver. In this case she can produce either black or liver gametes, so

This gives approximately a 50% probability that any given puppy is pure for black pigmentation, and a 50% probability that it is black carrying liver pigmentation.  All puppies “appear” black. We can get essentially the same diagram if the sire is black carrying liver and the dam is pure for black. Now suppose both parents are blacks carrying liver:

This time we get 25% probability of pure for black, 50% probability of black carrying liver, and - a possible surprise if you don't realize the liver gene is present in both parents - a 25% probability that a pup will be liver. Note: that only way to distinguish the pure for blacks from the blacks carrying liver is “test breeding” or possibly DNA testing.Another possible mating would be pure for black with liver:

In this case, all the puppies will be black carrying liver.    Suppose one parent is black carrying liver and the other is liver:

In this case, there is a 50% probability that a puppy will be black carrying liver and a 50% probability that it will be liver. Finally, look at what happens when liver is bred to liver:

Recessive to recessive breeds true!! - all of the pups will be liver pigmented!!!.
Note: that a pure for black can come out of a mating with both parents carrying liver, and that such a pure for black is just as pure for black as one from ten generations of all black parentage. THERE IS NO MIXING OF GENES. They remain intact through their various combinations, and B, for instance, will be the same B no matter how often it has been paired with liver. This, not the dominant-recessive relationship, is the real heart of Mendelian genetics.This type of dominant-recessive inheritance is common (and at times frustrating if you are trying to breed out a recessive trait, as you can't tell by looking which pups are pure for the dominant and which have one dominant and one recessive gene.) Note: that dominant to dominant can produce recessive, but recessive to recessive can only produce recessive. The results of a dominant to recessive breeding depend on whether the dog that looks to be the dominant carries the recessive. A dog that has one parent expressing the recessive gene, or that produces a puppy that shows the recessive gene, has to be a carrier of the recessive gene. Otherwise, you really don't know whether or not you are dealing with a carrier during test breeding.

The Dilute (D series) gene modifies the base color- black or liver- with a grayish blue like you see in Maltese and Russian Blue cats. The dominant side of the gene (D) is actually non-blue-dilute, and does not affect pigment. DD will not have blue-dilute pigment, nor will any of the offspring be blue-dilute. Dd does not affect pigment, but a blue-dilute offspring may be produced. dd is blue-dilute pigmented, and will always pass a blue-dilute gene to offspring, so they will either be blue-dilute or carry it. B/D Interaction Here’s where it gets interesting! When you see a dog that is a clear, easily to identify blue, it is likely that the blue-dilute gene is active over liver- one gene pair being bb and another dd. When blue-dilute is active over black points (BB with dd or Bb with dd), it becomes much harder to distinguish. Many people confuse the transmission of blue with that of liver, and think that a blue dog cannot support black pigment, and this is true, to a point. Remember that when you have blue-dilute over black, the black will be diluted to blue. Over good, black pigment, dilution can produce a strong gunmetal color in the hair that is VERY difficult to distinguish from undiluted black, and for all intents and purposes appears black, though you notice it shines blue in the sun!

How Do I Recognize Blue when it is over Black? This can be a very difficult task! Many a blue with excellent pigment for a blue is mistaken for a normal pigmented dog with poor pigment, and left out of the points for no reason! First, look at the pigment on the lips. In a blue over black, this will take on a lavender tint. When you see this, look CLOSELY at the nose. On a normally dark pigmented dog, the nose will look normal until you really look. There will be a blue-gray cast to the skin on the nose, sometimes so dark that it is difficult to see until you are out in sunlight! (If you are judging inside and in doubt, ask the owner- they should know! Remember blues are legal and no preference should be given for color!) The rims of the eyes will have the same lavender cast. Do not be fooled by eyelashes or eye stripes that look black- they may be a gunmetal color so dark you will not spot it except for the blue shine produced in direct sunlight. Hopefully this will help clear up some confusion!