Domestic dogs come clothed in hundreds of color, pattern and coat varieties, a pretty amazing feat for a species that developed from a rather drab-looking ancestral wolf. This ancient animal had a medium length brown to tan coat, just perfect for blending into his surroundings.
After dogs began their association with humans, however, they were transported into other areas and climates, and Mother Nature did the rest – 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. What does a "merle" dog look like? What's the difference between brindle and roan? And just what the heck is a particolor? Read on for a short course in dog color and pattern.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. Type 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. The length of the hair is often connected to the area in which the dog was originally developed.
In tropical areas, very short hair was preferred. This length of hair allows heat to be dissipated easier than long hair and is dominant over long hair. Short hair can be fine or coarse. Those breeds with short coarse hair have mostly primary hairs and fewer secondary hairs. An example is the coat of the Rottweiler. Some breeds, such as the dachshund, have a fine short coat. This is composed of primarily secondary hairs and fewer primary hairs.
Normal haired dogs have a higher proportion of secondary hairs to primary hairs. Examples include the wolf and German shepherd.
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. Coarse long haired dogs include the cocker and chow. Fine long haired dogs include poodles and Bedlington terriers. 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 Coat. In addition to a variety of coat lengths and hair types, there are also many different types of coat. Some common types include:
Hairless. There are a few breeds that are naturally hairless. This resulted initially as a genetic accident and has been perpetuated by selective breeding. The most commonly affected breeds are the Chinese crested and Mexican hairless.
Corded. In this hair coat, the coat hangs in long even strands of varying lengths. It is encouraged to grow into its natural ringlets and looks like dreadlocks. The breeds most often associated with this type of hair are the komondor and the puli.
Bear coat. This hair coat is created when there is a coarse outer coat and a soft dense and wooly undercoat. An example is the chow.
Wire Hair. In this hair coat, there are a much higher number of coarse primary hairs and those hairs are quite dense. Examples include wire haired fox terrier and the wire haired dachshund.
Curly 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.
Agouti Hair. In this type, the tip of the hair is light colored. The main body of the hair is dark and the base is light or red-brown. Examples include the German shepherd and Norwegian elkhound.
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. 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:
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.
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, which is recessive to short hair.
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.