from the magazine "Poodle-Revue"
M.N. Sotskaya.
These tails are not at all SIMPLE.
Genetics of tails.

Congenital shortening and tail defects can be caused by both dominant and recessive genes, which is confirmed by numerous observations. The available literature data relate mainly to the inheritance of anomalies, the information on normal tails is extremely scarce and quite contradictory.
So, Yu.N. Pilshchikov, on the basis of observations of shepherd dogs of different breeds, indicates that the tail of the saber-shaped form dominates them over the hook-shaped, annular and tail-log. At the same time, LF Whitney writes that the mestizo of the German shepherd and elkhound - a dog with a typical tail - had a tail in the ring, thrown over his back like an elkhound.

According to the oral reports of some experts - borers, in the Russian dog hounds the tail, twisted at the end in the ring dominates the straight.
Mestizos of wolves with dogs, regardless of the breed, tend to have longer and more curved tails.
I think that after a few years we will have our own data on poodles.

Genetic anomalies of the caudal department
Since the problem of tailings has become relevant for our breed, we will get acquainted with its anomalies described in dogs of other breeds.
Let me remind you that any deviation from the norm is considered a genetic anomaly. In this case, the anomalous sign does not necessarily represent a pathology.
Anomalies of the caudal spine in dogs have a large polymorphism from total absence to tail of full length, but with a number of curvatures. For dogs of some breeds (for example, English and French bulldogs), twisted tails represent the norm. Anomalies of the tail are most common in dogs of those breeds in which it is customary to terminate tails. This is due not to the inheritance of the acquired trait, but to the lack of selection in the tail for the tail of a normal structure, and individuals - carriers of anomalies - are not excluded from breeding, which we actually observe in our breed. The poodle often has a variety of curvatures of the tail, as well as its shortening.
It is obvious that the shape and length of the tail can be determined both mono- and polygenically.
Thus, Pullig (1953, 1957), based on the results of studies on dogs, believes that the absence of a tail and a short curved tail causes recessive genes an-anuria and br (Brachyury) - brachyuria.

Curtis et al. (1964) note the presence of the dominant St gene (stump), which contributes to the development of a short thick tail. Apparently, this gene has incomplete penetrance, so some dogs with the Stst genotype have a tail of normal length and shape. Selection for a short tail, conducted by these authors on laboratory beads, led to a decrease in the number of vertebrae in the tails. When breeding with the use of close inbreeding, puppies with spina bifida appeared.

The birth of puppies with normal-shaped tails is possible in the case of the non-allelicity of the genes an and br. In this case, if the allelic dominant genes provide a normal tail shape, the crossing will look like this:
PP ananBrBr X AnAnbrbr - dogs with anomaly
F1 AnanBrbr - dogs with a normal tail.

It is very likely that these genes are also not completely penetrant.
Changes in the shape and length of the tail can also occur due to a genetically determined violation of the shape of the caudal vertebrae, as well as partial coalescence.
Marked in the text of the standard, the abnormality called "squirrel" tail is associated with deformation of the first caudal vertebra, resulting in the tail lying on its back and practically unable to occupy a normal position or fall. Apparently, this anomaly has an autosomal recessive nature of inheritance.

Tail abnormalities and pathology.
At the same time, it is shown that a number of tail anomalies can lead to a variety of pathological changes.
Willis (1992) indicates the occurrence in dogs of such breeds as the Yorkshire Terrier, the Bulldog, the Pug, the Boston Terrier of the so-called semi-vertebra, that is, the vertebra of the wedge-shaped form. The nature of the inheritance of this anomaly until the end is not yet clear, most likely, it has a polygenic basis.

The wedge vertebra is also described in cats. With this anomaly, the vertebrae acquire a wedge shape and often coalesce, which leads to curvatures and various thickening of the tail, often in the form of knots. Vertebrae wedge-shaped forms can occur not only in the caudal region of the spine, but also in other departments. This, in turn, can lead to compression of the spinal cord and infringement of the roots of the spinal nerves, in a number of cases, causing paralytic phenomena and violation of trophism of the innervated organs.

There are several degrees of manifestation of this anomaly:
- some shortening of the tail due to deformation of the last vertebra or several vertebrae;
- curved, movable tail, due to deformation of one or more vertebrae in its different parts;
- shortened hook-shaped or knobby tail, due to deformation and fusion of separate vertebrae. Apparently, this allele is recessive with varying degrees of penetrance and expressiveness, which leads to its long-term preservation in populations, despite the culling of dogs with deformed tails.

Some authors, including NAIl'in, M.Burns and M.N. Fraser, L. Whitney argue that dogs with tail defects can have a reduced viability, similar to what is observed in animals of other species.

In particular, this concerns the length of the tails. Different degree of shortening of the tail is often found in dogs of different breeds. According to American geneticists M. Burns and M.N. Phaser, the shortened tail dominates the long one. And in the homozygous state, the short-tail may be lethal.
According to their opinion;
tt - tail of normal length
Tt - short tail
TT - homozygous carriers of these genes die in the embryonic period

A similar pattern is observed and well studied in the cats of the Isle of Man. These cats have shortened tails, the length of which varies from a total absence to half the length of the norm.
It is clearly shown that this feature is due to the dominant half-lethal factor M (Manx) with a lethal effect from the early embryonic stage of development. Lethality is associated with underdevelopment during embryogenesis of the tail of the neural tube. Analysis of embryo morphology in the fifth week of pregnancy showed that homozygotes of MM differ from normal embryos in a spherical shape. They have disorders in the development of the central nervous system, leading to death before birth (Robinson, 1993).

Heterozygous individuals Mm have a shortened tail, most often not accompanied by pathological manifestations. However, in some cases, the action of the M allele causes the development of defects in other parts of the spine, and possibly the spinal cord. For example, lack of lumbar vertebra, shortening of thoracic and lumbar vertebrae, splitting of vertebrae, shortening and anomalies of spinal processes, etc. These features are often accompanied by a clinical manifestation of pathology. For example, a change in the innervation of the bladder and the closing sphincter of the rectum leads to involuntary or constant urination and the release of feces.

Allele M may have a different degree of expression expressiveness, in addition, there are also modifier genes that enhance or weaken the manifestation of anomalies in heterozygous animals. Analysis of various phenotypic forms allowed to distinguish 4 versions of tails in cats.
1. Cats with complete absence of tail and caudal vertebrae - "rumpy" or true manx;
2. Cats that have only a few fixed fused caudal vertebrae - "rumpy-riser";
3. Cats that have much more vertebrae than rumpy-riser, the tail is mobile, but ugly in shape - "stumpy";
4. Cats with a short tail of normal mobility and shape - longie.

Similar deformities of the tail are often noted in dogs, including poodles. On the basis of N. Vavilov's homologous series, it is very likely that they can also be caused by genes with a lethal effect. It is possible that dogs with deformed or shortened tails may have nerve impairment in the lower extremity belt, urinary excretory organs, lower digestive and reproductive system, and so on.

Among the dogs several breeds with a natural short-tailed nature are described. Including those are bobtails, welsh corgi, schipperke. However, in these breeds often appear long-tailed puppies, which tails simply stop. And, since all dogs go to breeding, regardless of the length of the tail, then tailless and short-tailed puppies among these breeds are born less and less. This is the gradual eradication of an undesirable trait from the point of view of viability. And now most dogs of all these breeds walk around the rings with proudly raised unkempt tails.
Tails and constitution.

On the anatomy of the tail and the mechanisms of its movement is very well said in the article of N.A. Maslennikova about the exterior of the poodle in "Poodle Revue" No. 16/06. I also want to express some of my thoughts on this matter.
If we carry out a tour of all the breeds of dogs, then we can trace the distinct relationship between the format, the general type of constitution and the shape of the tail. It turns out that the tails that are most correct from the viewpoint of the poodle are found in dogs of a moderately stretched format that do not have such "drawn" hind legs. Actually this type was in our old large and small poodles mainly German breeding.

Modern shows of poodles of small varieties by the type of addition and format are most similar to Spitz-shaped dogs, small bishons, Basenji, etc. The vast majority of these dogs have twisted tails. Selection of a poodle in a square format, a short back, far-backed hind legs often pulls some crookedness straight and a high-ranking tail lying on its back. Since the tails were previously tied to the dogs, the peculiarity of their structure was not a significant breeding feature. Perhaps, it is this circumstance that made it possible to get poodles of a modern type show. On the contrary, if breeding were tailored to the tail structure, tails of the right shape would facilitate the selection of dogs of a moderately stretched format, and individuals similar in type to modern shows would be outside the standard. So now the breeders have a choice: what is more important to us is the formed type of poodle or the shape of the tail. Directional selection for the "right tail" will inevitably contribute to some simplification of the type.
The second danger that awaits us along this path may be the selection of dogs with abnormal tails.
How long should a normal poodle tail be? Recently, when cutting the tailings, we left them long enough. Measure the desired length in approximately the following way, the tail was bent to the stomach: the tail had to cover the loop with the tail, and the males had a slightly shorter pre-position. In this case it turned out that in one case it is necessary to cut off almost the third part of the tail, and in the other - just to pinch its tip. Shorter tails from nature tails are thicker and less bent. However, the question arises whether these tails are actually shortened and, consequently, genetically anomalous? Similar mutations are widespread in animals of different species, they are described in dogs.
In addition, I have repeatedly seen seemingly perfectly straight tails, but they were all clearly shortened, and some of them had slight kinks making the tail bend on the back impossible. This is also a genetic anomaly!

The problem of inheritance of shape and tail length is not so simple. It is known that a number of tail anomalies are associated with various pathologies and a general decrease in viability. Therefore, selection for short tails with limited mobility can lead us completely unknown where! So, it seems that the coveted straight tail is actually a kind of phantom.
Therefore, you can forbid "funny" tails, but what will it eventually result in? Do not we begin to consciously select for shortened or slightly deformed tails, or, on the contrary, will we again come to the old type of poodle of a moderately stretched format? Maybe the latter is not so bad?
Is not it easier to start kuping tails again? Obviously, in the case of imposing a ban on curled and twisted tails, a surgical correction of the shape and length of the tail becomes a good alternative to cupping.

Paradoxically, but perhaps this will bring less damage to the breed than selection for the tails of the right form!