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.

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