The following is from “Der Deutsch
Kurzhaar, The German Shorthaired Pointer” by
COAT
COLOUR/PATTERNING IN DOGS,
WITH PARTICULAR
REFERENCE TO THE GSP
Although
there is general agreement amongst geneticists as to the modes of inheritance
of most aspects of coat colour and pattern in dogs, confusion can arise due to
different lettering systems being employed by geneticists to describe the same
genes. The lettering system used by Dr.
Clarence C. Little (1957) in his book, “The Inheritance of Coat Colour in Dogs”
is widely used, and will be followed in this chapter, apart from the
description of the “A” series alleles, which is that used by Willis (1977).
All
dogs have the same number of chromosomes and the same number of genes
controlling the colour and pattern of their coats. The particular alleles of these genes,
present in a particular breed, however, are in many cases quite limited, and
the appearance of a colour or pattern
not normally found in a breed is usually indicative of cross-breeding. For example, a “GSP” with orange or lemon
patches is most likely to be a cross-bred animal. Why this is so will be made clear in this
chapter.
Some of
the genes mentioned are of little significance to the GSP, so they are included
without detailed discussion. Of greatest
interest to most breeders are the “B” series alleles, which determine whether
the animal will be black or liver and the “S” series which determine whether it
will be solid coloured or non-solid.
There are of course, variations in the amount and distribution of the
non-coloured areas and also in the amount of “ticking” or “roaning”
which is present in the white or non-coloured areas. These variations are dealt with separately,
with illustrations.
Because
of the confusion which exists amongst breeders and fanciers alike, I have dealt
most fully with the “B” and “S” loci.
Existing GSP books have included confusing information such as “ticking
is…a dominant gene”, given in a context which could lead one to believe that
the genes for ticked (non-solid) coat patterning were dominant to those for
solid colour-patterning. That, of
course, is the reverse of the true situation.
In fact, the true statement “ticking is dominant”, refers to the amount
of colouring found in the non-solid areas of the coat, i.e. clear white
(non-ticked) in contrast to ticking or roaning in the
non-solid areas. Even more misleading
are statements which describe dogs as being “liver and whites with solids
behind them” as if the solids might reappear in subsequent matings,
or “black puppies cropping up legitimately in liver to liver litters” or even
“black to liver may produce tricolours”.
All such statements reveal a misunderstanding of the inheritance of coat
colour and pattern in the GSP.
To
clarify this issue, I have included herein all the possible matings
of blacks to livers and solids to non-solids, together with the only
legitimately possible outcomes. To
simplify matters , all non-solid coloured animals, regardless of the
distribution or patterning of the coloured hairs found within the non-solid
areas of their coats (ticked, roaned or clear white),
are grouped together, with “s” to represent them.
Because
GSP fanciers tend to refer to most non-solid animals as “ticked”, I have added
“ticked”, when referring to non-solid.
The looseness of this terminology must be kept in mind when the genes
controlling the amount and distribution of coloured hairs in white areas are
discussed.
Using
this simplified system, I will then be dealing with only four possible
phenotypes, solid liver, solid black, liver/non-solid (“ticked”) and
black/non-solid (“ticked”).
The
nine possible geneotypes, illustrated in Figure 12.1,
are as follows: liver/non-solid (“ticked”), heterozygous-solid/liver, homozygous-solid/liver,
heterozygous-black/non-solid (“ticked”), homozygous-black/non-solid
(“ticked”), heterozygous-solid/homozygous-black, heterozygous-solid/heterozygous-black,
homozygous-solid/heterozygous-black and homozygous-solid/homozygous-black.
|
Figure 12.1 ALL POSSIBLE
GENOTYPES FOR COLOUR (BLACK AND LIVER) AND BASIC
COAT PATTERNING (SOLID AND NON-SOLID) (the circles indicate the colour/pattern carried by the dog) |
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12.1a bbss |
12.1b bbSs |
12.1c bbSS |
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12.1d Bbss |
12.1e BBss |
12.1f BBSs |
||
|
|
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|
12.1g BbSs |
12.1h BbSS |
12.1i BBSS |
||
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12.1a bbss… Liver & non-solid (“ticked”) |
12.1f BBSs… Solid black, heterozygous
for solid (carries non-solid (“ticking”) but not the liver colour) |
|||
|
12.1b bbSs… Solid liver, heterozygous
for solid, carries non-solid (“ticking”) |
12.1g BbSs… Solid black, heterozygous
for both solid and black (carries both non-solid (“ticking”) and the liver
colour) |
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12.1c bbSS… Solid liver, homozygous for
solid |
12.1h BbSS… Solid black, homozygous for
solid, heterozygous for black |
|||
|
12.1d Bbss… Black and non-solid (“ticked”),
heterozygous for black (carries liver) |
12.1i BBSS… Solid black, homozygous for
both solid and black |
|||
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12.1e BBss… Black and non-solid (“ticked”),
homozygous for black |
|
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The
distribution of the coloured patches, and the coloured hairs in the white areas
of the coat are not of great significance to most breeders and I have no wish
to fill this book with tables of the possible outcomes of matings
between “Irish spotted” or “extreme-white piebald” animals, or ticked to roaned or clear whites.
I have included however, illustrations of these various pattern types
and their modes of inheritance. Readers
may work out possible outcomes for themselves, using the given colour/pattern
tables as a guide.
There
is some disagreement amongst authors on the subject of ticking versus roaning, so I have included a hypothetical explanation of
the subject based on my own observations and breeding experience.
In Dr. Little’s book, the section on GSPs
attributes no genes for colour paling in the breed. Nor does he acknowledge the presence of
black, no doubt due to the fact that it is outlawed in the breed in his country
(the
Burns
(1952), using material gleaned from Danish studbooks, describes a litter of
eleven GSP pups, from two “normal” coloured parents, in which nine were “brown”
(normal) coloured and two were “cinnamon-coloured”. Burns ascribes this phenomenon to a modifying
gene “Z”, named by Steiger (1936). Willis (1977) mentions (without naming them)
five alleles for colour paling in the German Shepherd so it well may be that
another gene (or genes) other than the “C” locus gene is responsible for the
depth of colour in liver GSPs. However, I thought it worthwhile to point out
that a problem exists (most fanciers prefer the darker livers) and the “C”
locus gene alleles provide a possible explanation. I have therefore included illustration so GSPs with variations in depth of colour, caused by “C”
locus alleles (Figures 12.2d, 12.2c, 12.2f).
Interestingly enough, there does not seem to be a “pale” version of
black, although black dogs certainly can produce light liver offspring.
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12.2c AAbbCCDDEEggSSRR |
12.2d AAbbCCDD |
12.2f AAbbcchcchDD |
|
12.2c Solid liver |
12.2d |
12.2f Extremely pale solid liver |
Next Section: GENE LOCI FOR COAT COLOUR AND
PATTERN
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Copyright 2002 Georgina M. Byrne. All rights reserved. The
book in its entirety may be ordered by contacting Mrs. G. M. Byrne, Lot 31 Clayton Rd, Helena
Valley, Western Australia 6056 (Fax 09-294-1404) or Maria Bein,
1 Bittersweet Lane, Granby, Massachusetts USA.
NOTE:
This book is no longer in print and is not easy to find. Mrs. Byrne has several copies remaining and
additional copies may be found on ebay
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