Although the modern xoloitzcuintle as a whole is related to prehispanic populations, the phenotype (appearance) and genotype (genetic load) have been transformed over time. Since the mid-twentieth century a canophilic record has been created through which the genealogy of the inscribed xoloitzcuintles is known. However, most of the country's xolos are not registered, which poses a series of difficulties when it comes to accurately establishing the actual limits of this breed. It is not enough to lack hair so that a dog is constituted as a legitimate hairless xoloitzcuintle and there are also xoloitzcuintles with hair.
There is the initial registration, that is to say that a dog that does not have hair can be presented before an inspector who will decide its incorporation to the official registry. This option does not exist for a xoloitzcuintle with hair. Starting from such an event, a lineage begins that will gradually be established and recorded in the books of origins. Such a procedure is necessary to continue with the registration of the race and all the lineages started in this way. However, the problem is that although these dogs are phenotypically considered xoloitzcuintles, it is likely that some are actually mestizos, even very recent or in high proportion, although they carry the gene alopecia. In order to compensate the situation, the xolos with initial registration receive a certificate known as a genealogical certificate (green paper). Only after three generations have elapsed and the family tree has been completed, is the international pedigree issued (blue paper). Operationally, both registers allow the dog to access the same rights, although formally, the purebred is achieved until obtaining the blue pedigree. In fact, numerically, this should be extended to six generations, but the process has been reduced to three generations as a way of promoting the raising of both the xoloitzcuintle and the chihuahueño.
Unless we talk about extreme conformations such as the bulldog or a greyhound, most dogs have a moderate structure called mesomorphy. This means that if dogs of different breeds suddenly lost their fur, they would look reasonably similar. Because of this, while the race was handled as naked and wrongly discarded the xolos with hair of the official breeding and the very definition of the race, the xoloitzcuintle showed a tolerable uniform public aspect. The great dilemma began when he became aware of the importance of xolo with hair and he regained visibility. It turns out that there are xolos with long, short, wavy, hard hair, of different colors etc. Now the image process is reversed, naked dogs are suddenly covered with all this range of coats and the visual result is that they show a great diversity, which is not compatible with the definition of an established breed.
This is due to the fact that standardizing the nude dog by selective breeding could generate some consensus in structure, proportions, ears (raised) and other points, but the fur was a hidden variable. This could have been done for three generations or a thousand, anyway, without control, the fur would be extremely variable when examined, given the circumstances of the race. At the same time, it must be understood that variability is intrinsic to race in part because there is reasonable evidence to argue a broad chromatic range in historical terms. However, other qualities of the coat, such as its length and texture can and should be restricted since only the short coat is compatible with the tropical context of the breed. On the other hand, the erect ears are typical of dogs of primitive type. That is to say that a suitable way to have defined the mantle of the xolo with hair could be: short and in all the colors.
A set of dogs of the same race must be identifiable at first sight as such. That is, the image plays an important role. This premise and the knowledge of uncontrolled crosses made by many people for various reasons (carelessness, ignorance, lack of awareness, commercial purposes, trying to introduce characteristics of other races such as size, etc.), based a very tough reaction at the time of creating the current norm regarding the xolo with hair. The fur was rightly defined as short and the idea of erect ears is maintained, but color became a problem. There are colors that help to define certain races, for example the spotting of the Dalmatian is emblematic. Other colors, similarly though less precisely, are visually related to certain races. Certainly, if the hypothetical cross were made between a Doberman and a standard xolo, the Doberman would provide genetics for the black and tan pattern to occur. However, this same color existed in America since ancient times and then it is inefficient to say that a xolo with hair given, is black and fire for reasons of miscegenation. As simple as the color is not diagnostic of purity for the xoloitzcuintle due to its inherent chromatic richness.
Even so, the decision was forceful and was based on the image of the nude xoloitzcuintle to generate the prototype of the xolo with hair. In this way, the colors accepted officially for the fur, are the same as those that may exist in the skin of the nude xoloitzcuintle. This is inadequate for two reasons. The first and most obvious is that the skin and coat obey different genes and therefore do not express themselves correlatively. The second is that by doing this, he restricted himself to a large part of the breed's genetic pool without any real need. Paradoxically, vestigial hair of any color is allowed in a naked xolo, implying that all ported colors, but not visible, will continue to appear when these animals reproduce. The consequence is a constant cycle of production and discarding of xoloitzcuintles with fur for reasons of color.
As for the population not registered, although there are reasonably managed lineages, the demand for puppies and the ignorance of the buyers have caused an increase in the supply. People simply acquire a hairless dog and consider it as a xoloitzcuintle, that easy. Unfortunately, this is often not the case, and hard as it may be, many so-called xolos are simply mongrel dogs that also inherited the gene of nudity. A clear example is the very small puppies, but with an apple head, sold as miniature xoloitzcuintles, when in fact they are crosses with chihuahueño. If you add the fact that often people often want the reproduction of their canine companions, when this is done without control, the only thing that is generated is greater dispersion. On the other hand, with some guidance, some of these specimens far removed from the norm, could progressively produce offspring better and better. A dramatic case is when some of these bald dogs but with extreme intrusive genetic loads pass the inspection and enter the registry. The result is, for example, the hair xolo too long. In a sense, they are xolos because their parents are registered, but at the same time they are too far from the definition of the race. In the best of cases, they are very atypical xolos that for that same reason should not be perpetuated. The only alternative would be to stabilize a long hair shape, which up to now has no theoretical basis. It is worth mentioning the difference between litters and complete lines carrying this characteristic with respect to an isolated specimen in a lineage of dogs mostly of short hair. The second case can be interpreted as a product of genetic chance while the first case denotes an anomaly in the pool.
Faced with so many difficulties, the genetic proposal has even emerged to try to contribute to the "purification" of the xoloitzcuintle. This vision is extremely radical since it consists of establishing a genetic pattern, taking as reference old DNA obtained from an archaeological sample. To the extent that a modern dog is closer to the established genetic profile, it will be "purer" or "more legitimate". There are possible and relevant objections to this proposal. In the first place, the distance between the pre-Hispanic and modern population. On the other hand, the low representativeness of the profile, since a single old dog does not necessarily show what the entire population of his time was like. There is also the problem of which markers will be used and if these really reflect the phenotype (appearance). However, even though this type of proposal may be useful, the most worrisome is that genetic standards, when handled by one or a few people, can be used politically for the benefit of certain families of xolos and to the detriment of others. There is the possibility of whole families of xoloitzcuintles with long records and correctly managed that can still move away from the genetic pattern. Somehow, although the studies are relevant to scientific knowledge, for breeding they can be seen as trying to kill flies with cannons. No such sophistication is necessary and there is a risk of starting a nonsensical witch hunt by distinguishing certain lineages as "original" and others as "contaminated." Conceptually it would be like looking for the pure Aryan race, when it is known that all humanity, like the modern xolo has been genetically enriched by diverse processes.
The xoloitzcuintle with hair still faces a process before achieving its stabilization. It requires diffusion since even in the present many people ignore about their existence. On the other hand, institutional support is required to facilitate its registration, reproduction and presentation in public. Although the current standard represents an important advance and therefore an opportunity, it is still susceptible to improvement, especially in terms of extending the chromatic range allowed. The owners must make a self-critical reflection to locate each copy that is possessed in the complex panorama. While all dogs, regardless of their condition, deserve care and are worthy, they do not necessarily possess the genetic load necessary to support the continuity of such a beloved race. It is necessary to promote responsible registration and breeding and above all to try to achieve the best possible phenotypes but in accordance with the true nature of such an appreciated animal. Only then, the xoloitzcuintle will continue to exist as a cultural and biological heritage of our country.