The AKC Biewer Terrier breed standard has a paragraph dedicated to color so it is my goal with this article to discuss the different genes involved with what makes up the Biewer Terrier colors. You can find the AKC breed standard at this link: https://www.akc.org/dog-breeds/biewer-terrier/
“Color – The Biewer Terrier is a uniquely colored toy terrier. Head Coloring – Blue/Black, Gold/Tan, and White in good symmetry. Any combination of the following two colors, (Blue/Black and Gold/ Tan); (Gold/Tan and White) in good symmetry is acceptable. Body Coloring – Hair on back is blue/black and white. Amounts of each color are of personal preference with no dominating patterns. No amount of tan hair may be found on the back, belly, chest, legs, or feet. A small amount of tan hair may be found around the anus. Chest, Stomach, Legs, and Tip of the Tail – White. The white from the chest should come up the neck to cover the chin. Legs are to be white from the elbows and stifles to the feet. Disqualification – any other color or combination of colors other than those that are listed.”
First and foremost, the Biewer Terrier’s signature look is that of a long-haired tri-colored toy terrier. The breed is a Black & Tan Piebald with a few different modifying genes that can make individual dogs look very different from one another. For the purposes of this write up I will be quoting only a single main source for color genetics. Some of the genes are called different names within different breeds and I will try to include as many of those terms as possible with an explanation about them.
Piebald – (spsp)
“Piebald usually produces a colored head (with or without white on the muzzle and as a blaze), and patches on the body. Generally, the base of the tail is colored, but other than that the patches may be located anywhere on the body (but rarely on the legs).”
Piebald is also called “Parti” in the Biewer Terrier breed as well as the foundation breed, Yorkshire Terrier. This is a recessive gene, and so a dog must be homogeneous for it to allow the gene to be expressed. There have been a significant number of Biewers that have appeared to be Irish (si) rather than Piebald, but this gene can not yet be tested for so I will not address it here. The white of Piebald covers any color areas which are white. That is to say that if a dog is genetically Black & Tan as the Biewer should be, those standard Tan markings are still present on the dog, just hidden by the white. If the white does not cover the entire chest then we could expect to see some tan on that area which would be appropriate for a Black & Tan dog that did not have white at all. The same can be true for any color that is not covered by white which extends down the legs farther than the Breed Standard allows. By the Breed Standard there must be color on the head and somewhere along the backline, but the amount of color on the back is left open for breeders to select patterns they prefer. For health reasons, no one should be selecting for a split face or mismarks with white that covers one or both eyes or ears. If a Biewer is born with such extreme white it should be BAER Tested at the earliest appropriate age to be sure there is no hearing loss.
Tan Points – (atat)
“The range of markings on a tan pointed dog is very restricted. Red (tan) appears as pips above the eyes, on the sides of the muzzle extending to the cheeks, as pips on the cheeks, on the front of the neck just below the head, as two triangular patches on the front of the chest, on the lower legs and feet (and inside of the legs), and as a patch underneath the tail (and sometimes along the bottom edge of the tail too).”
The Biewer Terrier is homogeneous for tan points as a part of the breed’s hallmark signature color pattern of being a tri-colored dog. Since this marking is recessive a dog must be homogeneous for the trait to be expressed in the coat color. No other A Locus result is acceptable for the Biewer Terrier breed since any other A Locus result would produce a dog without tan points. The current Breed Standard only allows for tan on the head and around the anus which means that the rest of the dog should be white in any area that could show tan. It should be expected that if there is any infiltration of color into the areas known to have tan that there should be tan there if it is not covered by white. The Yorkshire Terrier breed calls tan on the body “running gold” and is a fault as it is also in Biewers. The amount of tan can vary within the Biewer breed as the tan points are influenced by the “Saddle Pattern” and “Creeping Tan” gene modifier, not to be confused with the layman term of “Running Gold” though caused by the same gene modifier.
Saddle Pattern and Creeping Tan – (RALY)
“The saddle/creeping tan modifier causes the black (or other eumelanin color) on a black-and-tan dog to “retreat” to the dog’s back, leaving the rest of the coat red. A dog with the creeping tan pattern has slightly more red/tan than a normal black-and-tan – usually spreading to the area around the eyes and extending further up the legs. The saddle pattern is the next step up from this, where the red extends over the whole head, the front of the chest/neck and the top of the legs, leaving black only on the back, tail and the back of the neck.”
The RALY gene modifier is responsible for the Yorkshire Terrier being born black & tan but later “clearing” to gold on the head and legs. This same gene modifier is present in the Biewer breed and most have at least 1 copy of RALY. There has been a recent influx of dogs that seem to not display the “clearing” of the head like the founding breed and these Biewers retain a mostly black head with minimal tan pips above the eyes and sometimes on their cheeks. Since all of the early Friedheck-born Biewers expressed a near fully gold head, one could surmise that the absence of the RALY gene modifier in some of these recent dogs might be the result of cross-breeding to another breed(s) that lacked the RALY gene modifier. Suffice it to say that we can now enjoy a multitude of colors and marking variation on our Biewers’ heads and most are described in the standard as being acceptable.
Masks – (Em)
“On a tan-pointed (atat) dog, masks can be detected by looking at the facial points. Tan normally occurs on the sides of the muzzle and above the eyebrows, but a dog with a mask may have all or part of these points covered up by the main coat color. Usually, however, the tan on the neck is usually still visible. Masks can vary greatly, covering anything from just the end of the muzzle to the whole of the muzzle, eyebrows, and ears.”
The Biewer breed does often carry the mask gene and it can easily be seen in most with a predominately tan head even when they have a white muzzle and blaze. When you see a white blaze with a dark outline along the edge of the tan, that is probably a mask. This gene was undesirable in the Yorkshire Terrier since that breed prefers a clear gold head absent of any dark or “muddy” markings. In the Biewer, however, the mask gene can create a very striking look and maintain a strong tri-color presentation on the head. The mask gene will obviously have no visible effect on the Biewers with predominantly blackheads but can still be present nonetheless.
Here I have covered the genes responsible for correct color and markings in the Biewer Terrier. There are also other colors within the breed but they are disqualifications by the standard. Liver (Chocolate) and Recessive Red (Golddust) exist in the Biewer in much the same way as they do in the Yorkie- On the outer fringes of the breed population. Keep in mind that while these color disqualifications can not be shown in the conformation ring, there are no health defects associated with them and so they make fine pets. Color does not define a separate breed, and so a Chocolate or Gold Biewer is still just a Biewer.