HARLEQUIN BREEDING FORBIDDEN IN GERMANY
a response to the ban by Friedmar Krautwurst,
translated by J.P. Yousha
& Monika Olbrisch
with assistance from Katja Hasslebach
(Ed. Note; There is currently a
ban on breeding any dog displaying merle or harlequin patterns to another dog
of like appearance. This ban is the result of political pressures brought to
bear by groups reportedly concerned that the genes involved result in
"defective offspring" and thereby, by definition, constitute
"cruel and abusive breeding practices". Harlequin to harlequin
breeding was banned by the Great Dane Club of
I will begin by
anticipating my argument: there is no well established genetic knowledge
concerning dog breeding to serve as a foundation to the recently enacted
breeding ban. This is not to imply insincere intentions to those political and
animal welfare activists behind the recent breeding ban; for it is undisputed
that the gene producing harlequins and merles, when present in a double dose
can result in defects of the sensory system. But what one must certainly
condemn is the hasty classification of the breeding of harlequins as "abusive"
without specific evidence.
It must be noted that
in the scientific literature no direct examination of the Great Dane is
contained within the so-called "reports of suffering and damage".
From the small number of animals examined, which did not include Great Danes,
but rather dappled Dachshunds, it is very risky to extrapolate to a final
statement concerning the legislation of dog breeding in general. First it would
need to be determined if an extrapolation from the Dachshund population to
other breeds is even justified. Do we even know whether the genetic inheritance
from breed to breed of identical phenotypic characteristics is identical,
totally different, or even results from completely opposite effects?
Knowledge concerning
the mode of action of the merle factor when present in a single dose, as exists
in the Harlequin Dane, remains unanswered in the current literature, as do
questions concerning penetrance and expression. For
the accountable representatives of political and
animal welfare groups, it suffices that breeding dogs of these coat colors is to be labeled as
"abusive". Their actions hence result in the opposite of their
intended goal; the destruction rather than the preservation of a type of dog
with more that a hundred years of cultural and historical significance. The
Harlequin breeder should take this particular opportunity to enlarge upon his
genetic knowledge concerning the merle factor.
The merle factor is
considered to be a dominant genetic mutation which inhibits, partially or
completely, the full pigmentation of the coat. The partial inhibition of
pigment appears phenotypically as a harlequin, a blue
merle, or other patched or spotted coat types; depending on the base coat color and what other recessive genes are present. If one
begins by describing the homozygous black dane
and designates this type dog as mm, then designates the harlequin as Mm genotypically, the presence of the dominant M allele
results in the partial reduction of pigment. With the complete mutation of both
alleles to the merle factor, a genotype of MM exists; a near total loss of
pigment and a white Dane resulting. Therefore can one deduce,
that in harlequin breeding there are three different gene pairs present
producing three different phenotypes:
mm - Blacks = do not carry the merle factor.
Mm - Harlequins = single factored for merle, i.e. heterozygous for merle.
MM - WHITES = double factored for merle, i.e. homozygous for merle
Clear and specific
knowledge about the merle factor and its relationship to structural defects has
particular significance for the breeder. These defects appear in the form of
sensory organ anomalies, such as variable congenital eye and ear defects, as
well as reproductive disorders. Because such defects can be problematic, and in
that they may not be apparent immediately, the cause and connections of the
desirable and undesirable features that result from the merle factor and their
mode of operation in both homozygotes and heterozygotes needs to be established. The linkage through
which the merle factor mutation produces both loss of pigment and anomalies of
the sensory organs can be accounted for by the connection between the shared
source of melanocytes and nervous structures in the
early embryonic neural plate. The resulting association in individual animals
of reduced pigmentation and sensory anomalies can be derived from this early
association in the neural plate. Simply stated, these defects can be attributed
to the development of early neural structures, which will later develop into
the sense organs, in close association with the initial stages of pigment
development.
In contrast to the
white Dane (i.e. MM), which carries the merle factor in a double dose, the
association of the occurrence of sensory anomalies with the breeding of the
harlequin (i.e. Mm) Dane, and thereby classification of such breedings as "abusive" cannot be established. The
German Great Dane Club (DDC) has determined that, in the future, as a
prerequisite for breeding harlequins, a hearing test must be furnished. A similar
method for a vision test is currently being prepared. Such testing on a broad
basis will provide greater knowledge concerning the genetics/breeding of
harlequin Danes. It may be possible to ascertain whether there is an
association between the location and size of pigmented areas and sense organ
functioning, and whether this is a general phenomenon or varies from individual
to individual. It is also possible that differential penetration of the merle
factor gene results in varying effects on the structure of the sense organs.
A broad measure taken
by the German Great Dane Club (DDC) is the prohibition of breeding harlequin
(Mm) Danes to each other to avoid the appearance of white (MM) Danes. The
breeder should clearly understand that, statistically, according to Mendelian laws of inheritance, the mating of two harlequins
will produce 50% harlequins, 25% white and 25% black Danes. From an analysis
done over 11 years and including 2200 progeny of harlequin to harlequin matings, a 14.6% ratio of white Danes was established.
These results confirm the assumption that the merle factor in double dosage (i.e.
MM) is sub-lethal. A
high mortality rate between conception and birth (i.e. embryonic death) results
for MM dogs. The currently imposed restriction to mating harlequin only
to blacks also results, on average, in 50% harlequin and 50% black progeny.
Double factored white Danes (i.e. MM) cannot result from such matings. Wise selection of breeding stock from these breedings can also produce well marked Danes. Blacks from
these breedings are free from the merle factor.
This discussion would
not be complete without a comment on the widespread confusion concerning the
description and phenotype of so-called white (MM) danes and their associated sense organ anomalies. In
the vernacular and the literature MM Danes are generally refereed to as
"White Danes". This description is lacking in the same way as
"Harlequin" as a term for the spotted or patched Dane. In the German
breed standard the "White Dane" is defined as "white Dane
without any black markings (albinos)". Both portions of the definition are
faulty: a completely white, doubled factored (MM) Dane is rarely found, and
albinos do not exist in the breed. In distinction to the above description of
merle factored dogs, albinos are produced, if, at the C Locus, both alleles are
recessive. In such a case, the chemical reaction that produces tyrosine, a
precursor of melanin, the chemical foundation for pigment, is prevented.
Therefore any trace of pigment will fail to appear in albinos.
The genetic definition
of a double merle factored Dane and its associated phenotype is very
complicated and uncertain. I know of animals recorded as White Danes which have
no associated sensory defects of any kind. The accompanying photo shows one
such individual swimming, who has no equilibrium disturbance due to deafness
and possesses normally functioning sensory organs. White dogs,
particularly when the result of matings between
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Copyright 2002 of translation by J P Yousha
and Monika Olbrisch, CHROMADANE. All rights reserved. Our thanks to the willingness
to share this article for educational purposes.