Coat Color and Pigments of the Shih Tzu
A dog's color depends upon the presence of pigmentation in the epidermis. Only two pigments exist; black/brown(Eumelanin), and yellow/red (Phaeomelanin). All dogs no matter what color their fur, 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 colourful exterior are 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. These mutations are not the only ones that affect color and pattern, but they are essential for the color, pattern and coat varieties. They are as follows:
Dilute, is recessive to dense coloration and creates a softer, paler version of a dominant color. Blue is the dilute of black, cream is the dilute of red and liver is the dilute of brown. All of these have self- colored points. They include cream with liver points; light and dark liver-chocolate; lilac (a blue/chocolate giving the appearance of lavender found only in dilute); and blue, which is recessive to black. This recessive gene is the only gene complex capable of changing the basic color of the points gene list above.
Piebald spotting factor creates areas of white. This gene is incompletely dominant and is affected by modifying genes. It causes the white areas to vary greatly in size and location. Long hair is recessive to short hair. All shih tzu’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, (ie B-black, b-liver, D-dilute).
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 gene factor, ie BB) 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 (one dominant factor and one recessive factor, ie Bb) 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 hormonal changes. 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.
Black-points gene dog with recessive (homozygous- having a double dose for that factor) dilute (aka blue 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 (with homozygous recessive genes); thus a 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. Some refer this color as lavender which is not recognized by the AKC. This is also out of the blue gene. They may also have blue eyes.
A Brown-points 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 hazel-blue to green. A dark eye cannot occur in the dilute animal.
Yellow-Red: coat colors include 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. 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 can be born pure black and when the hair grows, it can be a rich red color. Dogs can be born a creamy white and darken over with black masks, black tipping, black trace marks, or possible black brindling. If a liver point gene is present, no black can occur; thus may have liver masks, liver tipping 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 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 a liver color with 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. They also 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 or palest colors are more recessive and the darker and clearer ones are most dominant. In the liver, the coat color can range from beige to a deep chocolate.
Agouti Coloring: (Wolf or Wild Coloration) A lovely grey banded coloration with silver trim, which is found in the soft blue-silvers. 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 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.
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 and agouti can have these patterns. If an animal has both types of yellow-red, a small amount of pattern genes could show, such as a mask just beyond the end of the muzzle or a slight "ghost brindling or ghost mask". Pure extension (solid) 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. 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.
Gold, Gold & White, Red, Red & White, Cream, or Cream & White: Include dark and light cream, gold, or red. Creams 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 color seems is a 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.
Liver or Liver & White: This is a recessive gene. All liver-chocolates 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 darken 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. 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. They are a part of the blue gene group.
Lilac: Presently the rarest of all colors. It is a chocolate-blue dilute color giving the appearance of purple. Always found in dilute only. They are a part of the blue gene group.