WHAT KIND OF DWARF ARE WE?
by Charlie MacInnes, Finnshavn Cardigans, Canada.

24/10/05

Achondroplasia is probably the commonest form of dwarfism in humans, and it’s a nice
75¢ word, so we use it freely to describe the short legs of Corgis. That is WRONG. In
fact Corgis are more correctly described as hypochondroplastic (P. F. Jezyk, Chapter 57
In: Textbook of small animal orthopedics, C. D. Newton and D. M. Nunamaker (eds),
International Veterinary Information Service, Ithaca NY USA, www.ivis.org). The term
chondrodystrophic has also been applied to dwarf dogs, but that also is a clear error. That
form of dwarfism is related to malnutrition affecting growth. In these modern days of
scientifically formulated dog foods, fed ad lib, Corgis remain dwarf, so clearly they are
not chondrodystrophic.
Dwarfs come about when bones do not grow normally. The growth of long (leg,
arm, hand, foot etc.) bones in the skeleton occurs at two rings, just along from the bone
ends that form the joints. These regions are called growth plates. There is active cell
division on both sides of the plate, to form cartilage. Later on, this cartilage changes to
bone. Here are some definitions of parts of the big words. “chondro” signifies
cartilage, “plasia” means growth or expansion or proliferation, so chondroplasia means
the cartilage is proliferating. The root a- means none, but in fact that is impossible, in the
sense that, if dwarfs had no growth of bone at all on the limbs, they would have the limbs
of newborn puppies, and be unable to walk. The root hypo means less than normal, in
contrast to hyper, which is more than normal. Thus, the distinction between
achondroplastic and hypochondroplastic is subjective, and must involve criteria above
and beyond the mere lengths of limb bones.
My best friend and fellow birdwatcher in grade school was an achondroplastic
dwarf, so I was able to study the condition. In addition to the short, bowed legs and arms,
there were other clear anomalies. His face was relatively flattened, and recessed under a
high, domed forehead. His hands and feet were very short, with stubby fingers and toes.
Corgis have the shortened limbs, but their skulls and axial skeletons are those of
normal dogs. The muzzle is not short or flattened, and the forehead is not domed. Even
the feet are normal in size. Perhaps our preference for round or obovate feet represents
selection for slight dwarfism, but given that the paws are large, I doubt it. When a
Cardigan is high off the ground, it may be called long-legged. In fact, if you look
carefully, it is more likely to be long in pastern than in upper arm. It was not until I met
some Swedish vallhunds that I saw dogs with longer forearms and very short pasterns.
Vallhunds are normally about 2 – 3 cm taller than Cardigans.
Dwarfism results from partial failure of the growth plates of bones. In
hypochondroplastics, this affects mostly the long bones of the limbs. What is unknown at
present is whether the growth plates are just slow to produce bone, or whether they may
grow at irregular rates.
There is one medical problem with dwarfism in Cardigans. Puppies that develop
extreme bowing of the forearm may limp for several months. Bowing of the forearm
results from the radius growing more slowly than the ulna. If that process is too extreme,
the elbow and/or wrist joints may become dysplastic. I have an X-ray of the elbow of a
puppy I bred where the radius is so short that the part of the ulna with the joint face is
well beyond the actual joint. No wonder that puppy was limping! He did recover by
about 14 months of age, but I could not talk the owner into having another X-ray done.
The canine orrthopedic specialist who discussed the X-ray with me was the person who
alerted me to the idea that we don’t know exactly how the slow growth of the long bones
occurs. She agreed that they might stop and start, and, there is no guarantee that the two
bones of the forearm do that in perfect synchrony.
There certainly is a correlation between bow of the forearm and turnout of the
toes. Just as greater growth of the ulna than the radius can disrupt the elbow, it can cause
changes at the other ends as well. The most obvious change is rotation of the foot so that
the toes point outward. So strongly bowed forearms and turned out toes tend to go
together. The genetics are not at all clear: I have a male with too much curve to his
forearm and extreme turnout, but his litter brother has a too-straight front and no turnout.
Neither parent had pronounced turnout. I have also had extreme fronts turn up
unexpectedly, usually only one per litter. The lesson for Cardigan breeders is that we
must emphasize moderation in bow of forearm and turnout of feet, both central to
Cardigan type. The more extreme degrees are dysfunctional.
In humans, achondroplasia is thought to be controlled by a single recessive allele.
Jezyk suggested that hypocondroplasia might be allelic to this. In humans, an individual
is dwarf or not dwarf (at least in the case of achondroplasia), with no evidence of
intermediate sizes. Indivduals of normal size who have dwarfs in their ancestry can
produce dwarfs. I believe that the genetics of dwarfism in Corgis represent a more
complex situation, probably as a result of prolonged selection for a package of functional
dwarf characteristics. The major evidence is that crosses of Cardigans with other breeds
are intermediate in terms of limb lengths. I do not know enough about breeding from
such crosses to know whether there are distinct size categories – e.g. “dwarfs”, “halfdwarfs”, etc., or whether there is a continuum of sizes in later generations from these
crosses.
Dachshunds are known to suffer from degenerative disc disease. Corgis do not
appear to suffer from bad backs as frequently as dachshunds. One rule of thumb is that
dogs of either breed are more likely to develop disc problems if they are walked only on
leash, or in small back yards. My dogs are walked off leash, over uneven ground on a 10
ha property, twice a day. They run loose with enthusiasm, and in doing so develop and
maintain excellent muscle tone. Human chiropractors will confirm that human couch
potatoes are most likely to have back problems.
There are bits of Corgi lore that fall into the old wives tales category. One is that
if you allow a Corgi puppy to exercise too much, it will grow longer legs. While it is
plausible that a lot of activity might stimulate the faltering growth plates, there is no
evidence that this actually happens. My dogs live on 10 ha, and puppies are allowed
hours of outdoor activity, yet I do not have longer legged dogs. Another old piece of
Corgi conventional wisdom holds that you should carry a puppy up and down stairs until
it is at least a year old, lest it damage its shoulders from the pounding coming downstairs.
Again, because Corgi puppies, especially the well-fed (spoiled) are stout, this is plausible.
However, I have allowed Corgi puppies to do stairs when they want to, for more than 30
years, without adverse effects. There are much more probable reasons for a puppy to
become temporarily lame on its front.
Lloyd-Thomas claimed that the dwarfism of Cardigan Corgis originated from
teckel (dachshund) stock. He further claims that the Pembroke Corgi dwarfism
originated from somewhere else. I doubt the latter, but there is room to speculate on the
relation to teckel stock. There is little doubt that the Corgis have been with the Celts a
long time. The earliest signs of the Celts in archaeology are jewellery and other burial
artefacts in the salt-mining country of Bavaria and adjacent Austria. Coincidentally, that
is the region where the teckel stock has produced the greatest number of breeds. From
Bavaria the Celts traded over much of Europe, and produced major settlements in eastern
and central France. Eventually, Celts reached Galicia, in the northern part of the Iberian
peninsula, and from there they spread north to Irelend, Scotland, Wales, Cornwall and
Brittany. Caesar had major battles with a group of Celts in east-central France. Their
leader, Vercingetorix, agreed to be executed, in return for the Romans sparing the rest of
his people. If the Celts had dwarf dogs in Bavaria, they have left evidence of that in the
beagles, bassets, and terriers of France as they passed through more than a millennium
ago. Celtic traders were known in Denmark at the time that the Norse ruled there, so the
dwarf stock might have reached Scandinavia by that route, and possibly even come south
to the Welsh coast in a Norse ship. All of the modern dwarf-legged dogs of Europe share
with the Corgis the fact that their heads and bodies show little evidence of dwarfism. On
the down side of the teckel hypothesis, Jezyk reported that careful study of dachshunds
by McCusick indicated that they were not as easily classed as hypochondroplastic as the
Corgis, bassets, and many terrier breeds. However, modern DNA studies may help
unravel this mystery.
There is still much to be learned about the dwarfism of Corgis.