Inheritance of Coat Color

 

In this article gene theory as it relates to Italian Greyhounds will be discussed.  Only the bare essentials of the issue will be explored. Readers are encouraged to read in depth books and articles on inheritance of coat color.

Coat color in dogs is controlled by a series of genes.  Unfortunately the genetics of coat color in Italian Greyhounds is not a simple issue in which only one or two alleles control the outcome of color. Several factors must be taken into account when studying color outcome in Italian Greyhounds.

 


A Genetic Primer

 

"A" - The Agouti Series

The genes which form this series of multiple alleles influence the amounts and location of dark or light pigment in the individual hairs of the whole coat. The following is the list of alleles in dominant order:

 

 


ay
- restricts the dark pigmentation and produces what we call red but is more properly termed, sable.   In the Italian Greyhound, it is believed that all carry this gene.

**no current photo of recessive black, but probably looks just like a back in IG's**

a - Allows the distribution of dark (black) pigment  hairs over the whole body.  At one time, the "a" gene was considered the dominant, but since has been shown that it is not.  It is rare for the IG to carry what is now called "recessive black".

**no current photo of a blue & Tan or Black & Tan IG available**

at - produces the bi-color we commonly call "black and tan" (blue and tan, red and tan, etc.). This allele is only included because of the possibility that this color exists. Modern breeders are breeding away from this color combination because the breed standard does NOT include it. IGs which present this color combination are disqualified in dog shows. It is most probable that this allele no longer exists in the majority of Italian Greyhounds but since it is a recessive gene, it may still be lurking in some bloodlines.

There is also other alleles to this series but will not be discussed here as it is not present in Italian Greyhounds.

 

"B" - B Locus

This is perhaps the most well known series of genes in dogs. Only two alleles exist for this series.

B - Produces black pigment and black coat.

**no current photo of Brown pigment available**

b - Produces brown pigment and brown coat.

It seems likely that the majority of USA Italian Greyhounds are homozygous for BB.   It seems to be a rare report (USA) of brown nosed or  "chocolate colored with brown nose" (bb) Italian Greyhounds.   It appears more frequently in Europe than in the USA.   There have been rare instances of true chocolate Italian Greyhounds in the USA. These dogs will always display a brown or liver colored nose.  Most IGs currently called "chocolate" are likely a variety of what is known as "seals" if the nose pigment is black.

 

"C" - Albino Series

The genes which form these multiple alleles influence the depth of pigmentation. This is perhaps the most interesting series. This series could explain the variety of "shades" we see in Italian Greyhounds. Nose pigmentation is not affected by this series.

C - allows full pigmentation. Deep reds, deep blues and deep blacks best illustrate the affect of this allele on coat color.

ch - suppresses the pigmentation: creams, light fawns, light blues. This gene does not appear to have an affect on black coat.   However, there is speculation that it may have something to do with "Seal" Italian Greyhounds and why they seem to be a blend of both Black and Brown(red) coats.   It may allow the "sable gene" to seep through in color.

There are other alleles to this series but are not known to be present in Italian Greyhounds. Although the cd allele in this series is known to produce white coat with black pigment and Italian Greyhounds are known to sometimes appear in this color it is more than likely such a dog is actually produced by another gene called the spotting or "S" series. The spotting series will be discussed later.

 

"D" - Dilution Series

Only two alleles exist for this series. This series does not cause the color but acts upon other loci (gene) to cause different expression of those genes.   

For example with a Blue Italian Greyhound:    the blue IG (phenotype) is genetically (genotype) a Black dog, but has the dilution gene which changed the base color of Black to blue.

 

D - intense pigmentation  - Black nose, lips and eye rims, pads of feet and whiskers will be black.  The above Black and Sable IG's both have Black pigment.

If the "D" is present either singularly (Dd) or duplicate (DD), the color of the coat will be expressed by other loci.   The Black nose color will be displayed.

b    

d - dilution of pigment.   Although the pigment looks almost black in these photos of the two "blue" dogs, their pigment is blue.  The fawn exhibits a blue nose and a blue casting of hairs about the face.  This gene does not affect the sable (red) coat, only black hairs and pigment.

In Blue IG's or blue pigmented red/Fawn dogs, the dilution gene is recessive, so the dog will carry two copies "dd".   The   intensity of color of blue will depend upon other loci and modifying factors.  The color of the red is not affected by the dilution gene, but will turn any normally black hair to a blue color. 

This gene will turn black coats into what we call "Blue" as well as turn the nose pigment from black to blue.

 

"E" - Extension  Restriction series

There are multiple alleles to this series but only those relevant to the Italian Greyhound will be discussed. This series either extends dark pigment or restricts dark pigment.

Em - Dominant to all other alleles in this locus. This gene produces the black mask seen in some Italian Greyhounds. This mask is best seen in fawn or red colored Italian Greyhounds.   The mask is usually on the muzzle and extends up the face. A black Italian Greyhound may carry this gene but it may only be seen  in a light colored dog.


E - Allows the extension of dark pigment without a mask.   The above puppy shows no masking . 

 

e - restriction of dark pigment.  This recessive gene if found together (ee), will change the black coloration of a dog's coat to the above color (cream).  In other words, the recessive "e" gene will mask the black color.    It does not affect the pigment of the nose and pads.  This is also known as "e-reds".   So a dog who is genetically black, with the presence of this gene will have the black coat turned to either a Cream color or a shade of Red with NO black hairs - including no black whiskers.    The above dog is almost white in color and is considered a "cream" color in IG's. 

 

G - greying series.

All Italian Greyhound's are homozygous for "g'. The dominant "G" causes progressive graying of the coat as seen in Kerry Blue Terriers. These dogs are born black and as they age their coats turn grey. There have been no reports of this occurring in Italian Greyhounds.   The mention of this gene is only for those who may have heard the term "Graying gene" and have wondered if that is the gene that causes the "Blue" in Italian Greyhounds (no).

 

K - Black

  

A relative new-comer to the genetic world is what is now known as K-Black.   Formerly it was thought that this color was controlled by the Agouti series "A", but new DNA techniques have shown this not to be true.     There are two genes within this series that do affect the IG.   The third gene, Kbr (Brindle) is not a gene that should occur in IG's so will not be discussed.  

K - this gene hides the agouti series "ay" (sable) and causes the dog to be Black.   An Italian Greyhound who is black will be ayayK?   (The ? mark is used to denote not knowing what the second copy of the gene is for a dog. )  A Black Dog could be ayayKK (cannot pass on anything but the dominant Black gene or ayayKKb  (has the ability to produce Black or Sable).

Kb - this gene is recessive to Dominant black (K) and allows the expression of the "ayay" sable gene in Italian Greyhounds.  So the Italian Greyhound who is ayayKbKb will be sable in color.

 

"S" - Spotting series

There are several alleles to this locus which exist in the Italian Greyhound. This series controls the amount and expression of white markings.

 

S - solid color. Modifying factors may influence the expression of a small patch of white seen on the chest, or white toes.   The above dogs exhibit minimal to almost no white markings, having just patches of white on toes or on chest.

 

Si - irish spotting. This is a definite pattern with white appearing on the muzzle, chest, legs, neck and tail. Modifying factors control the amount of white seen. Plus factors may extend the white up the legs or cause a large "collar" of white around the neck. Minus factors may restrict or cause no white collar around the neck but allow white boots upon the legs.   The examples above showing the white markings in varying degrees are all considered to be "Irish" markings.

v

Sp: piebald. This is where white covers 50% or more of the body. Plus and minus factors influence the amount of white seen.   The above examples are markings which  would be considered "pied" or "piebald" in Italian Greyhounds.

v

Sw - extreme piedbald. Usually this is an all white animal. Plus factors may cause the ears, eyes or head to be colored. This is not a common gene in Italian Greyhounds. Most whites with colored heads are more likely to be sp in origin with modifying factors creating mostly white. There are a few bloodlines of Italian Greyhounds that do carry the sw allele.   All four above dogs would be considered extreme pied.

 

T - Ticking Series

There are two alleles to this locus. Flecks of color will appear in white areas. The most well-known breed for this series is Dalmations.

T - produces the ticking.   The above photo shows the heavy ticking on the skin that shows through the white coat.   The actual hairs are white, it is the skin that has the heavy ticking.  Ticking is not necessarily present at birth but as the dog ages flecks of skin-color will appear within the white areas of the dog. The color of the ticking will be the determined by the dilution gene.   In Italian Greyhounds ticking seems to be only on the skin and does not change the color of the white hairs.

t - no ticking will be seen.   The above photo shows no underlying ticking on the skin.

 

 

 


For further reading on this subject, see the next article on Italian Greyhound Coat Colors.