Short-leggedness is one of the defining traits for many dog breeds.
From a veterinary and scientific point of view, the small warts of the corgi, dachshund or basset are actually a developmental disorder:
Canine chondrodystrophy and chondrodysplasia.
And even dog breeds, where this is not so obvious at first glance, are affected by short-leggedness. These include, for example, the French bulldog and many hunting dogs such as terriers and spaniels.
But how does this phenomenon actually come about? What goes wrong in order for the dachshund to get its dachshund legs?
Canine chondrodysplasia and chondrodystrophy
Small dogs naturally have shorter legs than large dogs.
But with dwarf dogs you can differentiate between proportioned short stature (e.g. Sheltie or Miniature Pinscher) and disproportionate short stature in the really lower dog breeds (e.g. Corgi or Dachshund).
So dwarfism and short-leggedness are different phenotypeswhich also differ in their genetic causes.
A dog can be dwarfed and be short-legged or just one of both.
By far over 20 dog breeds a more or less pronounced short-leggedness is one of the defining characteristics according to the breeding standard.
- Alpenländische Dachsbracke
- Basset Griffon Vendéen Small
- Basset Hound
- Bolonka Zwetna
- Bichon frize
- Cairn Terrier
- Cotton Tulear
- Dandie Dinmont Terrier
- Glen of Imaal Terrier
- Norwich Terrier
- Small Podengo
- (Low-legged) Russell Terrier
- Swiss low-legged dog
- Scottish Terrier
- Shih Tzu
- Skye Terrier
- Tibet Spaniel
- Welsh Corgi Cardigan
- Welsh Corgie Pembroke
- West Highland White Terrier
- Yorkshire Terrier
With other dogs, too, it is immediately noticeable that sometimes all or at least some representatives are significantly longer than high:
- Bavarian Mountain Welding Dog
- Cavalier King Charles Spaniel
- Cocker Spaniel
- Clumber Spaniel
- German bracke
- English Springer Spaniel
- English bulldog
- Entlebucher Sennenhund
- French bulldog
- Miniature and toy poodle
The origin of short-legged dog breeds
The description of short-legged dogs goes back a very long time. It is likely that the decisive mutation is already relatively old and has only been preserved through breeding selection of this curiosity.
For a long time, the targeted breeding of short-legged hunting dogs was primarily about performance and not about beauty, racial unity or breeding standards.
So until not so long ago there was a lively exchange of genetic material between dog breeds.
It cannot be ruled out that the responsible mutation has occurred several times in the history of the domestic dog.
However, it can be assumed that almost all short-legged dogs are more or less related to one another and that the short-leggedness goes back to one or a few common ancestors.
What happens with chondrodysplasia and chondrodystrophy?
In normal development in dogs, the bones of the legs lengthen as they grow due to the formation of new cartilage cells in the so-called cartilage cells Growth plates or epiphyseal plates.
These cartilage cells are pushed inwards from the bone ends (epiphyses), die and serve as building material for the growing bone matrix.
To put it simply: the legs become longer.
This process runs in normally built dogs until the beginning of puberty, only then does the growth slowly ebb away.
The development of the young skeleton is controlled by a complex network of processes that have not yet been fully researched. Everything has to be in the right place and grow in the right direction at the right time.
This development is disturbed in dogs with chondrodysplasia or chondrodystrophy.
Chondro- refers to cartilage tissue.
One Dysplasia is an abnormal development (e.g. in hip dysplasia the acetabulum is not properly developed). One can Chondrodysplasia so simply generally referred to as abnormal growth of the cartilage tissue of the young dog.
One Dystrophy on the other hand, describes a developmental disorder caused by degenerative processes. Chondrodystrophie also denotes an abnormal growth of the cartilage tissue that deviates from the norm, but which in the dog is often associated with further degenerations.
The cartilage tissue of the growth plates of the long tubular bones ossifies prematurely. The legs can then no longer grow in length, the dog remains more or less short and often a little crooked-legged.
One also speaks of asymmetrischem Zwergwuchs.
In many cases the ulna and radius also end the growth offset, so that the “radius curvus” occurs: Inwardly curved forelimbs with outwardly positioned feet (We’d better not talk about the claws …).
Genetic causes of chondrodysplasia and chondrodystrophy in the dog
There are some hereditary diseases that do also can lead to short legs.
For example, there is a genetic test for a special form of chondrodysplasia in the Karelian Bear Dog, Norwegian Elk Dog and Chinook. Another form of skeletal dysplasia is known in the working lines of the Labrador Retriever. And dog breeds such as German shepherds or poodles also suffer from their own forms of dwarfism, which lead to a whole range of stunted growth.
Mutation in short-legged dog breeds
Of course, for many short-legged dogs, leg length is not considered a deficiency.
In fact, it is highly desirable that all representatives of certain breeds of dogs be the same Long should have short legs.
And we now know that the leg length in these dogs logically also has a genetic cause, but is a bit more complicated:
To the surprise of the researchers who examined the phenomenon in 2009, no mutation was found in any of the genes present in short-legged dog breeds.
Dogs that the breed standard calls for short legs have one or more additional legs instead Kopien of FGF4-Genswhich should only occur once in normal dogs.
The FGF4 gene contains the blueprint for a protein that is used as a growth factor (fibroblast growth factor 4) is involved in normal skeletal development in dogs.
Dogs with Multiple FGF4 Genes actually produce more of this growth factor.
In fact, you don’t really know why more Growth factor in the end for fewer Growth ensures.
One theory is that due to the increased concentration of this protein crucial processes in the dog’s embryonic development are switched on too early and ended prematurely.
Early start and misfire in the elongation of the long bones, so to speak.
There are currently two known locations in the genome of short-legged dogs where an additional copy of the FGF4-Retrogens (if you are more interested you can find both studies below in the sources).
” One Copy of FGF4 on chromosome 18 is found particularly often in smaller dog breeds with a chondrodysplastic physique such as Cairn Terriers, Pekingese, Maltese or Westies.
” One Copy of FGF4 on chromosome 12 is found more often in larger dog breeds with a conspicuously rectangular build such as Beagle, Frenchie, Entlebucher Sennenhund or the small Poodle varieties.
And even with dog breeds that sometimes only –oops– produce somewhat short-legged members of the breed, this mutation is held responsible, for example in the Chesapeake Bay Retriever, Nova Scotia Duck Tolling Retriever, or the Portuguese Water Dog.
” And a Copy of FGF4 on each chromosome 12 and on chromosome 18 is found especially in dogs with very short legs. So the effect seems to increase when a dog carries both mutations:
- Alpine Dachsbracke
- Dandie Dinmont Terrier
- Swiss low-legged dog
- Skye Terrier
- Welsh Corgi Cardigan
- Welsh Corgie Pembroke
However, just looking at the mutations in different dog breeds cannot be differentiated from one another.
On the one hand, the transitions between different body shapes are very fluid. Second, it is not a completely dominant phenomenon (not every wearer is equally affected).
In addition, both mutations occur more or less frequently in many short-legged dog breeds. Perhaps this explains why some small dogs seem to have legs halfway and other dogs of the same breed only to have stubby legs.
Torture breeding? Short legs and health
It is now known that a Copy of FGF4 on chromosome 12 with a greatly increased susceptibility to disc problems (Hansen’s Type I intervertebral disc disease, IVDD) in the carrier dogs goes hand in hand.
The problem here is not just the unfavorable length-height ratio, but actually cartilage of the intervertebral discs at a young age.
Other problems associated with chondrodystrophy are Jaw deformities or misaligned teeth.
But not every dog with this mutation is equally affected by all symptoms, it seems to be a dominant phenomenon with incomplete penetrance.
Short-legged dogs with only the FGF4 copy on chromosome 18 but without the FGF4 copy on chromosome 12 do not seem to be affected by the increased IVDD type 1 risk, but are affected by theirs unfavorable physique nevertheless often severely disadvantaged in life.
Dachshunds and bassets in particular are getting longer and stubby-legged due to the massive show breeding of the last few decades. Some dogs are said to have barely any wart any more.
Especially for dogs that carry both mutations at the same time, the risk increases in the course of life orthopedic problems to suffer even more of course overall.
Dachshund owners have known for a long time that their darlings shouldn’t be pulled into the air by the harness, shouldn’t jump and should also avoid stairs.
Im „Expert opinion on the interpretation of Section 11b of the Animal Welfare Act“Of the Federal Ministry of Food and Agriculture, disproportionate dwarfism in dogs is listed under the” problematic breeding goals “.
In general, they don’t have much good things to say about dwarfism in dogs:
With the introduction of the trait in breeding, there is a willingness (disposition) to a number of diseases, e.g. B. herniated disc, […], Misalignment of bones and joints as well as difficult births. – Expert opinion on the interpretation of Section 11b of the Animal Welfare Act
Since this rather rare genetic phenomenon became known, dogs can be tested for both mutations at almost all relevant laboratories (here, for example, the link to the test at Laboklin).
Gives In many short-legged dog breeds, both mutations actually occur with a certain frequency in the gene pool, here the breeders are asked to proceed systematically over the long term.
Through targeted selection of breeding partners In terms of breeding, one could move towards the short-legged form, which is not burdened with an IVDD type 1 risk, without having to completely forego the desired phenotype.
Until then, breeders of these dog breeds have little choice but to keep a particularly critical eye on IVDD incidents in the relatives of their breeding animals and to make friends with the idea to risk a little more leg.
Short-leggedness is also malleable to a certain extent in terms of breeding.
If you have managed to make the legs of some dogs almost completely disappear, you could have this effect …