Color Genetics of the Australian Shepherd Dog


The blue merle Australian Shepherd (Aussie)  is really a black dog that also carries the merling gene. (Photo from the book.)

Aussies with merle, black, and red coats.

When most of us think “Aussie” or “Australian Shepherd Dog” we envision a little blue herding dog with a merled coat.  But Aussies actually come a variety of colors, including red, red merle, solid red, solid black, and even white with black heads.  All the solid colors can be with or without white markings and/or copper (tan) points. White trim is allowed on the muzzle, top of the skull, foreface, neck, chest, stomach, feet and legs. It can vary from a small amount to full blazes, collars and stockings.  Figuring out what color you can get from a specific breeding can be quite simple in some cases, and quite confusing in others, depending upon the color genetics involved.

A tricolor dog (black with tan markings on face and legs).

In her wonderful book All About Aussies, Jeanne Joy Hartnagle-Taylor gives an in-depth analysis of how these genes work and what to expect when breeding various coat color combinations.  For instance, a black dog may have either two black genes (black/black) or one red and one black gene (black/red).  The Aussie that has two black genes will pass on only genes for a black coat and will produce only black puppies when bred to another black/black Aussie.  The other black Aussie (black/red) with one black gene and one red gene, commonly known as red factored, will produce black puppies unless the other parent is a red Aussie with two red genes or a red-factored black.

A solid red Australian Shepherd.

“A red Australian Shepherd when bred to another red will produce an entire litter of red puppies. If a red Aussie is bred to a black Aussie that has only black genes, the puppies will be black, but those black puppies will now carry one red gene. When they are bred to another red-factored Aussie, both red and black puppies may appear in the litter.”

A piebald patterned dog with fully pigmented eye rims and nose.

“Piebald genes often express by extending white markings up the stifles and connecting white coat underneath the body of the dog. The piebald gene produces irregular, non-symmetrical patters of white. For example, the Aussie may have a fully colored body with a white splash somewhere, or he may have a fully colored head with a white body and only a few colored spots.”  These patterned white puppies are not defective like the double merle whites and should not be confused with them.  A patterned white Aussie may have a fully colored body with just a white splash, or a fully colored head with a white body and just a few colored spots. The ears and eyes are surrounded by full pigment.

Merling is a pattern, not a color, and appears on both black and red coats. When a merle is bred to a solid color Aussie, the puppies inherit the base color as above, in addition to the merling pattern.  Solid black or red Aussies, when bred to another solid color Aussie, will produce only solid colored puppies.  When a solid, non-merled Aussie is mated to a merled Aussie, the solid, non-merled Aussie can provide only a non-merled gene, while the merled parent with one merled gene and one non-merled gene can pass on either a non-merled or merled gene to his offspring. When a puppy inherits a solid, non-merled gene and a merled gene, the puppy  will be a merled color.

When two merled individuals are mated (each carrying solid/merle genes), some pups will inherit a non-merled gene from each parent resulting in a solid coat color. Some puppies will receive a merled gene from one parent and

a non-merled gene from the other parent, resulting in merle coat colors.  The remaining 25% of the litter, statistically, will receive two merle genes, one from each parent. These puppies will be  defective double merle whites. These puppies are almost all white in appearance, and may or may not have a few merle spots or dilute speckles. The individuals have no pigment on the eye rims, lips, nose and pads and their hearing and sight are almost always impaired. In some cases they eyes are not formed, or the pups have defective organs or no eyes.  The only time these defective whites occur is when two merle individuals are mated together and the pup inherits two merle genes. All the acceptably colored puppies in the litter will be perfectly normal.

Both solid and merled puppies with black or red base coat color can occur in a single litter, depending upon the genetic makeup of the parents.

An Irish pattern also affects color and this gene controls the white marking that appear on the muzzle, foreface, topskull, feet and legs, and tip of the tail. The Irish pattern is controlled by a separate gene from either the base coat color or the merling gene.

Classic marking include a white blaze, collar or ruff, and white feet, but the also vary. White markings are determined by a gene for Irish Pattern.

You’ll find much more about genetics and the mode of inheritance of various traits of the Australian Shepherd dog in All About Aussies: Australian Shepherd from A to Z

Photos in this blog are not from the book.

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