We should say goodbye to the word “pure breed” as this concept does not exist scientifically even for dogs, cats, horses, etc. etc.
The term is improperly used only due to custom or cultural ignorance because from a biological point of view there is no clear distinction between different groups of individuals of the same species.
In the specific case of dogs, science tells us that there is only one species (CANIS FAMILIARIS), a single form of dog descended from the wolf for many distinct populations depending on the environment, the climate and the practical use perpetrated for centuries.
It is work that determines the phenotype (race) and not vice versa); It is true that dog breeds are still the result of a selection that took place over hundreds of years by crossing dogs of different lines from a phenotypic point of view.
It was only in 1873 that some London Victorian nobles, inspired by the family tree of their racehorses, began to talk about the concept of “pure breed” for dogs too.
The F.C.I. was born in 1911. who perfected this concept of purity, with all the negative consequences that followed and which is perpetuated up to the present day.
This artificial selection of specimens, with certain homogeneous physical characteristics, are written in an official dog breeding standard (E.N.C.I. – F.C.I.) but this type of selection has reduced the genetic pool of subjects over the years and has caused the appearance of many hereditary diseases.
From a genotypic point of view, dog breeds all resemble each other and are the result of natural and subsequently artificial selection, by crossing dogs of different breeds and phenotypes.
What we see in “pure breeds” is only the phenotype
(cit. by E. A. Ostrander – geneticist)

So when today you find yourself facing a debate on the validity of one association rather than another, be careful not to make a bad impression by saying stupid things, because the real validity of an association that aims to protect one or more breeds it lies in his truly applied protection project and in the professionalism with which he carries it out.

font. V. Meneghetti