Genetic coat color

Genetics: The old staple reference material for explaining coat color inheritance was a series of very nice diagrams written for and included in the  Shiba. Here are the old coat color diagrams that have become a guide for many:

In Shibas, the A series (Agouti) codes for distribution of black pigment known as eumelanin, on red, sesame, black and tan dogs, with varying intensities of red pigment (phaeomelanin). Agouti is one of the oldest color genes (such as found in wolves, and is associated with very “ancient” breeds of dog like the Shiba).

Ay is sable (which can be red with or without black tipping), and is dominant over at (tan points gene in black and tans). A dog with an Ay inherited from both parents is AyAy and is expressed as clear red, Ayat is expressed as “sesame” and atat is expressed as black and tan, which is recessive to Ay. So a red dog AyAy bred to any other color will give you red AyAy and sable Ayat, but not black and tan, UNLESS the dogs genotype is actually Ayat but appears red (phenotype) due to lack of expression of eumelanin. This seems to be very confusing for people, myself included I admit, and breeders and pet owners often seem to wonder “is my dog red, sesame, or red sesame if nothing else? And what about those red headed black and tans?”

To make it more confusing, Shibas also have a second type of sesame that produces banded hairs (aw) aka wolf-grey/agouti. This gene is slightly dominant over at, and less dominant than Ay for expression, which explains a lot of the incorrect “sesames” observed.  Red and sable dogs do have banded hairs (all Shibas should have banding) but not all have this wolf-grey effect over their entire bodies (think Shikoku). This gene is responsible for wolf grey color, and may be what people who say “true sesame” are thinking of.  aw is very very very rare in Shibas, and it is also recessive.

Most of what you see will be sable dogs with red undertones and some scattered black tips over their back and tail (sashige). For registration purposes, these dogs are often called “Red Sesame”. The big problem as I see it is trying to breed true sesame from pairings of reds and black and tans, hoping to produce aw agouti, but we get dirty reds instead. Well, if the genes aren’t there to begin with, they can’t be passed on.

The other important gene series determining coat color is the E series. This determines the dogs’ ability to express its other coat color genes normally.

The A locus expression is directly affected by the E locus, in that the A locus is not expressed in ee dogs. So, a dog that is dominant EE has normal extension and expresses whatever color pattern it has in the A series, as does a dog who is Ee. An ee dog is a recessive red dog and can have any of the genotypes AyAy, Ayat, awaw, awat, atat, but will never express black hair.

All cream dogs are ee, but some red appearing dogs are also ee. An ee dog does not express Agouti series color normally, as the gene(s) for cream don’t compete for expression in the same way as red, sable/wolf grey, and black and tan, and prevents the dog from producing eumelanin (black hair). So, recessive ee dogs never have black pigment in their coats, but can range in hues from light red to yellow to cream. Shiba puppies with no black or grizzling whatsoever in the coat, if not already obviously cream, would be ee and could produce cream or very diluted reds, if bred to other ee or Ee dogs.

A potential problem results from intentionally selecting ee dogs over time in breeding, which could cause the gradual loss of diversity of sable, agouti and black and tan, as well as coat quality, as ee prevents expression of eumelanin, and this pigment does affect coat texture (more pigment=coarser thicker guard hairs). Although it is recessive, the risk is the increasing number of heterozygous Ee animals who won’t express dilute red, but will pass it on unknowingly unless genetic testing is performed. This could result from popular sire/dam effect very easily, and we can see this has already happened in the past with Kishu and Hokkaido, who are now almost entirely ee.

Current theory is that there is a new locus that controls intensity of phaeomelanin red dilution in Shibas, the I locus, which results in cream coloration in ee dogs.  It affects all phaeomelanin (red) in the coat and handily explains why we see very washed out reds, black and tans with no tan points, and cream color inheritance. Another reason to be wary of selection of ee.

Lack of pigment like this would obviously be an issue long term in breeding as it will over time affect coat quality and color and ultimately health (as with any extreme selection). Hokkaido tend to have very nice coats, but they still retain very nice specimens of red, black and tan, brindle and sesame dogs that are bred from and shown (not so much with Kishu). Both breeds are still fairly inbred and the colors are diminishing in quality, as the majority of their populations are now white.

So, cream/white dogs are likely caused by extreme pigment dilution resulting from a combination of at least 2 processes. The Total Shiba uses the C locus (Chinchilla) to explain cream in Shibas and many breeders do still explain cream color inheritance this way, but this is no longer believed to be accurate.

URAJIRO

by Leslie Ann Engen
published in 1997 Feb/Mar Shiba-E-News

First, lets get the pronunciation right! There are four syllables: u/ra/ji/ro. The u is pronounced oo as in the word food. The r in ra is slightly different from the English r, more like an l or d or a Spanish r without any flip or roll. If you fin it difficult to pronounce, use an English r sound. The a is pronounced like a in father. The gee in the word, gee whiz will do nicely for the ji. And, the r in ro is the same as above; the o as in the word boat. All together now, URAJIRO – oo/ra/gee/ro!

The Japanese do not have a dictionary definition for this word because it is a two-part word. The first character, ura, means the reverse side; the undersurface, or inside. The s word. You thought English difficult?

So, urajiro means undersurface white, which in English, is really a description rather than a word. Another English word for undersurface is ventral. If you remember that sharks and dolphins have a dorsal fin on their backs, it’s easy to remember that ventral means the opposite of dorsal. We could say that all Shibas must have ventral white, but this single word, urajiro, far better brings the image to mind.

The Nippo Standard states that all Shibas are required to have urajiro in the following areas:

1. The mouth sides and cheeks 2. Each undersection of the jaw, neck, chest and stomach 3. The forechest, extending to the shoulder joint, but not extending onto the shoulder itself

The Federation Cynologique Internationale (FCI) standard for the Shiba uses the word urajiro in its English translation. It defines it as “a whitish coat on the sides of the muzzle and on the cheeks, on the underside of the jaw and neck, on the chest and stomach and the underside of the tail, and on the inside of the legs.

The inside of the ears and eye spots were not included in this list but probably should be since they are part of the same set of genes. As with everything about Shibas, the amount of urajiro a dog should have is moderate – neither too much nor too little. The line between the red coat color on the dog and the urajiro is not clear-cut, but rather, is slightly blurred. This is because the urajirt characteristic is linked with the kind of red coat the Shiba has. The gene that controls the Shiba red always shades to a lighter color on the belly of an adult dog. It is completely different from the gene that makes a solid red dog like an Irish Setter.

The Nippo Standard for the Shiba also makes reference to other white markings that are acceptable but not required, and most important, these white markings are not urajiro. They are:

1. White socks on the forelegs no further than the elbow joint; rear legs no further than the knee joint 2. The tip of the tail

Another example of this type of marking is the patch of white blaze on the chest of a newborn Shiba puppy, standing out clearly from the brownish baby coat. Many times these newborn chest patches or tiny toe socks will fade into the urajiro as the puppy grows up. They’re still there, you just can’t see them anymore. Less desirable white markings that sometime occur are a snip on the bridge of the nose or forehead, a white spot on the back of the neck, or a white collar like those seen in Collies and Shelties. All of these markings have clean-cut edges. All are controlled by the same set of genes. Again, they are not urajiro.

Hopefully, you are no longer asking why should we use the Japanese word urajiro in the United States. Remember:

1. It consolidates all of the required white areas (controlled by the same set of genes) into one word. It clearly separates the required – from the not required optional white areas (i.e., socks and tail). 2. There is no simple translation of the word into English; one that can give these white areas a similar and consolidated identity. 3. FCI has already incorporated this Japanese word into the English FCI Shiba Standard, making it an international term.

URAJIRO? . . . the required white markings on a Shiba!

 

A good explanation of the importance of Urajiro is found here: http://www.shibas.org/newstand/urajiro.html

More about extreme white, piebald, pinto, and Irish spotting: http://www.doggenetics.co.uk/white.html