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Dachshund Double Dapple
Breeding dapple to dapple can
produce Double Dapples and they can have very
serious genetic issues that can cause puppies to be born without eyes,
deafness and other body abnormalities. Double Dapples are not accepted by
the Kennel Club UK or USA Clubs. Quite a few Breeders in the U.S.A do breed DOUBLE
DAPPLES. Currently in the UK this doesn't happen with responsible KC
breeders. The reason breeders risk trying to breed a Double Dapple is that
they will eventually get a normal perfectly healthy dog and that dog will
look truly stunning (see picture below) with additional white patches over the normal single
dapple. Double dapples can be bred by mating two dapples - the pups from
that mating will be normal colours, single dapple and double dapple. If two
double dapples are bred together then all the pups will be double dapples.
From time to time red and cream dapples loose their dapple over time and are
mistakenly then taken for shaded reds, creams and thus bred with single
dapples, so it is important to try not (unless you fully understand the
risks and implications) to breed single dapples with reds or creams
just in case these dogs have lost their dapple colouring.
Double dapples can be indentified by
patches of WHITE in addition to normal dapple markings.
More information and pictures can be found HERE
The big PLUS? of a double dapple is
it will always produce all dapple litters NO MATTER WHAT COLOUR THE OTHER
DOG IS so essentially this issue is more about disreputable breeders being
greedy given dapples normally fetch more money than base colours and those
who are prepared to maim a few dogs for the sake of pretty colours. We do
not breed double dapples not would we encourage anyone else to do so.
| Double Dapple |
Dapple |
Black/Chocolate
and Tan |
SAFE? |
Pups from
Breeding - Note % is a guide prediction and may or may not be
correct! |
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X X
As of 1st January
2010 no dapple to dapple matings will be allowed to register pups
with the KC |
|
NO |
25%
Base colour, 50% Single dapple, and the issue in this
equation 25% Double dapple which may or may not have health
issues but more likely than not. This mating could of course have no
doubles in it but the possibility is there so you shouldn't do it.
|
|
XX
As of 1st January
2010 no dapple to dapple matings will be allowed to register pups
with the KC |
|
|
NO |
1100%
double dapples which may or may not have health issues but
more likely than not. |
| X |
|
X |
SAFE |
1100%
single dapple |
| |
X |
X |
SAFE |
50%
Base colour, 50% Single dapple |
| Double Dapple |
Dapple |
Red/Cream |
SAFE? |
Pups from
Breeding - Note % is a guide prediction and may or may not be
correct! |
| |
X |
X |
MEDIUM |
50%
Base colour, 50% Single dapple - This mating contains the
risk that pups may go unidentified as dapples and thus cause a
dapple to dapple mating at a later point in time. It is our personal
recommendation that the
ONLY SAFE OPTION
with pups from such a litter is that from a breeding point of
view they should always be regarded as dapples even though
they don't show visible signs of being dapples - see
Phantom Merle. When the merl dna test
finally becomes available we would recommend any pups that DON'T
look like a dapple from a litter
containing a dapple parent be tested regardless of appearance. At
that point should they test negative they may
safely
be regarded as non dapples. |
Long technical version
Dapple is the name used with Dachshunds but is
the same as Merl used in other breeds. Canine coat colour is determined by the
expression of a specific combination of genes. A gene, the basic unit of
heredity, is comprised of a unique sequence of DNA and directs the
production of a specific protein. Proteins are required for the structure,
function and regulation of the body’s cells, tissues, and organs. Genes are
located within chromosomes. Dogs have two sets of 39 chromosomes in every
cell, one set inherited from each parent. The location of each gene within a
chromosome is referred to as its locus. While there is more than 99% DNA
sequence similarity between dogs, variations in DNA sequence do occur in a
small number of genes. Different forms of the same gene are called alleles.
Dogs can have two identical or two different alleles for a particular gene.
If both alleles are identical, then the dog is said to be homozygous at that
gene; if both alleles are different, then the dog is said to be heterozygous
at that gene. The genotype of an animal is its genetic identity, as
identified by the alleles it carries; while the phenotype, or appearance, is
the expression of those alleles. Coat colour in dogs is usually controlled by
a set of genes. These include the colour genes, genes that affect the pigment
colour of hairs, and the pattern genes, those that affect the distribution of
a particular colour. At least 20 genes have been identified that affect coat
colour in dogs.
Merle-Dapple Coat Colour
Patterning
The merle coat colour is characterized by patches of dilute pigment in
combination with areas of full pigmentation. Therefore, the merle gene acts
to lighten whatever coat colour would otherwise be expressed. However,
unlike other dilution genes, the lightening effect is not spread evenly over
the coat, but is expressed as patches of diluted colour scattered over the
dog’s body. If the basic colour of the dog is black, the effect of the merle
gene is a soft gray, often referred to as “blue”. If the basic colour of the
dog is red, the effect of the merle gene is a pale red. The merle coat
pattern is characteristic of a number of breeds including the Shetland
Sheepdog, Collie, Border Collie, Dachshund, Australian Shepherd, Cardigan
Welsh Corgi, and Pomeranian.
Genetic
Inheritance of the Merle-Dapple Gene
The merle gene (M)
is inherited in an autosomal fashion. In other words, the trait is not
linked to gender and can be passed on from either the mother or the father.
The gene is incompletely dominant, or a gene that has intermediate
expression. A heterozygous dog, carrying only one copy of the merle gene
(Mm), expresses the characteristic diluted coat colour pattern. A non-merle
dog (mm) is normal in colour, while a homozygous double-merle (MM) is
predominantly white. Punnett squares can be used to determine the expected
coat colour of offspring when breeding dogs of known genotype (i.e. coat
colour genes have been identified). In the example illustrated, a non-merle
dog (mm), indicated in the vertical column, bred to a heterozygous merle
(Mm), indicated in the horizontal column, will give rise to offspring with
an expected frequency of 50% merle (Mm) and 50% non-merle (mm). Dogs that
carry the merle gene but do not show the characteristic merle phenotype, are
known as cryptic merles. These dogs may give rise to merle offspring. It is
suspected that the DNA sequence of the merle allele in the cryptic is
shorter than the allele expressed in the typical merle dog. The harlequin
coat colour pattern in Great Danes is produced through the interaction of the
merle locus and the harlequin (H) gene. In harlequin Danes, the merle
background colour is diluted to nearly white with fully pigmented black
patches.
Health Problems
Associated with the Merle-Dapple Allele
You should never breed two heterozygous merle (Mm) dogs together because it
produces the homozygous double merle (MM). Homozygous double
merle (MM) dogs may exhibit auditory and ophthalmic abnormalities including
mild to severe deafness, increased intraocular pressure, ametropia, microphthalmia and colobomas. The double merle genotype may
also be associated with abnormalities of skeletal, cardiac and reproductive
systems.
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Ametropia:
vision impairment due to a refractive error such that images fail to
focus upon the retina.
-
Microphthalmia: a smaller than normal eye due to a defect occurring
early in development. Affected dogs may have prominent third eyelids.
Other eye defects are common in animals with this condition, including
defects of the cornea, anterior chamber, lens and retina.
-
Coloboma:
a defect in ocular tissue; a cleft or missing portion of components of
the eye, most commonly affecting the iris.
Phantom merles
Merles that do not
have the merle phenotype (appearance) may still have the merle genotype
(Mm). These merles are called phantom merles or cryptic merles. Phantom
merles should never be bred because they may produce phantom merle
offspring. Phantom merles may accidentally be bred to other merles
(Mm) which would produce devastating (MM) merles with the health problems
described above.
Other websites with
Dapple information
Dachshund Breed Council Dapple information sheet - please click here
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