| Are
crooked tails of any interest to breeders or judges? by J.H.C. Brooijmans-Schallenberg,
veterinary and judge The tail vertebrae belong to the
spinal column and the spine is again a part of the skeleton. The formation of the skeleton
starts in a rather early stage of the embryonic development, to be precise in the
mesoderm. Also in this mesoderm begins the development of the vascular system, including
the heart, the muscular system and the urinary/genital systems. The complete development of the
impregnated ovum to a newborn pup and the later growth of the animal is determined by
hereditary factors. By studying the development of the vertebral column of a mouse, it is
observed that approximately 20 hereditary factors are responsible. It is a rather
complicated process, so it is obvious that something can easily go wrong. Mutations are not uncommon. That
is why defects occur in the genome. If it happens in the genes and the defects are then
transmitted to the offspring. Gene defects don’t always show in phenotype. The causes
are many. The way of inheriting (recessive or dominant) is one of them, but also the
interaction between the different kind of inherited factors. Important is the number of
heterogenesis i.e. the variability in the genotype. Deformities of the tail vertebrae
are part of skeletal defects. They can be various in shape, and depend on the defect in
the genotype. The tail can be completely gone, or be too short with a rather blunt end or
a bobtail. The tail can have one or more bends (kinks) in different variations, hooks and
crooks. Sometimes there are too few or too many vertebrae, even sometimes double. We have
seen defects in mid spinal articulations as well. Crooked tails can show a few weeks after
birth. When the deformity is limited to
the tail then it has no influence on the dog’s life, he can be a happy dog. But when
that happy dog is used, as a stud his “little defect” can become much more
serious for his offspring. Not only to the tails but also in other parts of the spinal
column. There are dogs born with deformed vertebrae of the neck, breasts, back and loin.
There are also examples of puppies with a split palate, hydrocephalus, wry jaws, deformed
ribs, too many or too few toes, too short legs (from knee to foot). As a result of the interactions
between different hereditary factors there can arise defects in other organ systems which
are developed in the mesoderm. Examples are persistent embryonic blood vessels, septum
defects, ectopic ureter, the absence of an anus and cloaca formation. These defects are
mostly categorised as birth defects not heritable. Possibly, but when it is not proven to
be a non-heritable defect we must play safe and assume that hereditary components play a
part in the matter. The reverse opinion “ show me that it is inheritable” can be
quite dangerous for the breed. The link between the named
deformities in the organ systems and the crooked tails found in parents or relatives of
both parents is proven in quite a few cases. These deformities are also seen in other
species namely pigs and mice. In mice scientific research has proven the above. It is always highly irresponsible
to breed dogs with a crooked tail that means a tail where the vertebrae are not in a
straight line but crooked and deformed. It goes without saying that the same thing applies
for bent backs, deformities of the ribs, crooked jaws, short legs and too many or to few
toes. Judges have a duty to examine the
dog they judge very carefully and that must include the tail. Skeletal defects and also
other problems to health and well-being of the dog or its offspring must always be noted
for further information to breeders and owners. For that matter these dogs should never be
evaluated as top quality. It is in fact a devation of the correct image of the dog. Breeders especially the ones
interested in breeds which tails are docked must be very alert to the tails of the newborn
puppies. They (the breeders) should keep a record and they must inform the future owner.
The request of a “non-breeding” restriction on the pedigree is recommendable. When all of us accept our
responsibility, it will mean that we are concerned about the health and well-being of our
dogs now and in the future. |