White Patterns

Dogs can exhibit many different white pattern phenotypes. The genes that control these phenotypes can be present alone, or they can interact with other genes to produce still more patterns. For example, both the harlequin, which is found in Great Danes, and the ticking or roaning white patterns, require other genes to express. All of the white patterns (with the exception of harlequin) start with a white pattern spotting gene.

White Spotting

A beagle exhibiting the piebald phenotype. Open Source Photo

A Boxer who is a good example of the extreme white phenotype. Open Source Photo

A Boston Terrier with the Irish Spotting phenotype. Open Source Photo

The term "white spotting" is used to describe any of the plain white markings that dogs can exhibit. White spotting in dogs tends to follow a pattern, starting with the toes, chest, and tip of the tail; it has an upward progression, leaving the head and the base of the tail as the last solid areas. In the past, it has been theorized that there are four (4) different alleles that can be inherited at the S, or Spotting, locus. These were S (solid), sⁱ (Irish Spotting), s^p (Piebald), and s^w (Extreme white). Recent studies, however, suggest that what was thought to be caused by a separate allele s^w is instead the result of dogs being homozygous for s^p (piebald). The piebald pattern (at least in the breeds studied) has been found to correspond with a mutation in a gene known as MITF and is inherited as a recessive to S. Dogs that are s^ps^p exhibit either a piebald or an extreme white pattern. The piebald pattern typically has some blotches of color on the body, with a solid head and base of the tail. Extreme white may be almost completely white or retain some color on the head. The extreme white pattern has been known to cause deafness. This is thought to be caused by the lack of pigment in the inner ear and is also seen in some splashed white horses. The differences in expression between piebald and extreme white are most likely the result of white boosting or suppressing genes and are well within the range of expression for known white patterns in other species.

The Irish Spotting is a separate mutation and is also recessive to S. In some breeds, specifically Boxers, it has been found to have a co-dominant inheritance relationship with s^p. Meaning that when a dog is sⁱs^p (Flashy White) it has more white than it would if it was sⁱsⁱ (Irish Spotted) but less white than if it was s^ps^p. Irish Spotting generally takes color from the legs, chest, and underbelly but does not put white spots on the body. The type of Irish spotting found in boxers is also a MITF mutation. But some patterns labeled Irish Spotting in other breeds appear to be caused by a separate mutation that is likely not located on MITF. It is also possible that other white causing mutations exist, but have yet to be identified. For more information on White Spotting, see How the Dog Got It's Spots

Ticking

An Australian Cattle Dog with a Blue Ticked phenotype. Open Source Photo

An Australian Cattle Dog with the Red Ticked Pattern. Open Source Photo

Ticking is a pattern of colored hair that occurs inside what would otherwise be white markings. This means, that in order for ticking to express, a white spotting gene must be present. The ticking is always the color that would have been present if the area had not been white. For example, if the area would have been black, the ticking is black. If, as in the legs of a black and tan dog, the area was tan, the ticking will be tan. Ticking is not present at birth but starts to develop about the third week of age. Ticking is inherited as a dominant and this has occasionally resulted in an unticked pup being born into a breed that requires ticking for registration.

Dalmatian Spotting

A Dalmatian dog with its distinctive black and white coat pattern. Open Source Photo

Dalmatian spotting is a pattern that is the result of three separate genes. These genes are the extreme white pattern (s^ps^p) , the ticking gene, and a third modifier gene. This third gene organizes the ticking into large “dots” of color, instead of the ticking pattern more commonly seen. It follows a recessive inheritance pattern.

Harlequin

A Harlequin Great Dane. Open Source Photo

Harlequin is a white pattern that is found only in Great Danes. It is visually similar to Dalmatian spotting (with bigger blotches of color), but the mechanism is completely different. Harlequin is not dependent on any of the white spotting genes, but rather on merle. If merle is not present, even if the gene for harlequin is, the Great Dane will be normally colored. The harlequin gene acts to make white, any of the patches of color that would have been diluted in a merle dog. The remaining colored splotches will be the base color of the dog, and while black on white is preferred, they can be any color found in the Great Dane breed. Harlequin has been found to be an embryonic lethal; therefore all harlequins are Hh. Because the merle gene is involved, and harlequin is embryonic lethal, it is recommended that harlequins never be bred to other harlequins or merles. For more on merle, please visit the Dilutions and Modifiers page.

Panda

A German Shepherd with The Panda Pattern. Photo courtesy of Phenom Shepherds

The Panda Pattern first occurred, as a spontaneous mutation, in a German Shepherd named Lewcinkas Franka Von Phenom (Frankie), in the year 2000. She was quite the surprise to her breeders when she was born. In order to find out why she had so much white, she was taken to Ohio State University Veterinary Hospital. There, her parentage was verified; but the cause of her white pattern could not be definitively determined. The pattern continued to be studied until the causative mutation was located by Mark Neff, Ph.D., a geneticist at UC Davis. The mutation was found on the KIT gene, a gene widely responsible for white patterns, regardless of species; and like many other KIT gene mutations (although not all) the Panda White Pattern is an embryonic lethal when homozygous. This means that pups that are homozygous for the Panda Pattern do not develop in the womb and are reabsorbed very early in the development process. Because this happens so early in development, this does not affect the health of other pups in the same litter or the health of the dam. Panda is a semi-dominant mutation (homozygous embryonic lethal) that can visually look very similar to an Irish Spotting pattern. It causes white on the limbs, belly, neck, and face, with the white being concentrated toward the front of the dog. The front legs will often have white above the knees, while the back legs will have much less, often just on the toes. Blue eyes are uncommon. Dogs with the Panda Pattern not more prone to deafness or other maladies than any other German Shepherd dog.