64 Saber Tails Fall 2018
Petit Basset Griffon Vendéen Club of America
Good News for Our Short-Legged PBGVs!
by Laura Liscum, PhD, Health Committee
P
BGVs were bred to hunt small game in the thick, brambly
undergrowth of western coastal France. The short legs and
wiry coat of the PBGV give the hound an advantage when s/
he is pursuing rabbits through the thorny underbrush. The
PBGV originated from the much larger Griffon Vendéen be-
ginning in the 16th century. As the breed developed, both
the height and the length of the dog were reduced. That is,
litters were examined for proportionally smaller littermates
that exhibited the desired qualities of an enthusiastic rabbit
hunter.
W
e have known for several years that the genetic cause
of short-leggedness in PBGVs is shared with other short
dogs (Parker et al. 2009). Apparently, a chunk of DNA containing the gene encoding fibroblast growth factor 4 (FGF4)
was duplicated in some ancestral dog and the second copy of that DNA inserted itself far away in dog chromosome
18. Dogs with this extra duplicated DNA make more of the growth factor, FGF4, which counterintuitively signals long
bone cells to stop growing. This FGF4 insertion into chromosome 18 is found in PBGVs, Basset Hounds, Pembroke Welsh
Corgis, Dachshunds, West Highland White and Scottish Terriers, as well as other short breeds.
D
r. Danika Bannasch, in her seminar at the 2108 PBGVCA National Specialty in Reno, told us that there are short-legged
breeds that don’t have the FGF4 insertion into chromosome 18. What causes their shortness? Also, there are some
breeds that are normally long-legged but have a few short-legged examples within the breed, such as Dr. Bannasch’s
favorite breed, the Nova Scotia Duck Tolling Retriever. To make things worse, the Tollers with abnormally short legs are
also susceptible to Hansen’s Type I intervertebral disc disease (IVDD). This inflammatory degeneration of discs leads to
severe pain and nerve damage in young affected dogs. Short legs combined with IVDD is known as chrondrodystrophy.
Dr. Bannasch’s lab set out to determine what causes the abnormal short-leggedness in Tollers. They found that the
short-legged Tollers have a duplicated FGF4 gene, but in this case the second copy of FGF4 is inserted into dog chromo-
some 12 (Brown et al. 2017). This abnormal insertion leads to shorter legs, but also a greater susceptibility to IVDD. They
then examined other short-legged breeds to determine if they also have this newly discovered mutation. The insertion
was found in all of the Dachshunds that were tested. So, this very short breed has TWO genetic causes of shortness. It
was also found in all Beagles that were tested as well as a large proportion of French Bulldogs, Pembroke Welsh Corgis,
and Basset Hounds, among other breeds. Those breeds that have high incidence of the insertion into chromosome 12
are also known to have a predilection for IVDD.
W
hat about PBGVs? Thankfully, this mutation was NOT found in PBGVs. While PBGVs may sporadically have IVDD due
to other risk factors, they are NOT genetically pre-disposed to this affliction. That is very good news for the PBGV
community!
FGF4 insertion into chromosome 18 = short
legs. PBGVs have this insertion.
FGF4 insertion into chromosome 12 = short
legs + risk of intervertebral disc disease.
Hooray! PBGVs do not have this insertion.
Photo from the PBGVCA Judge’s Education presentation