The BVA/KC hip dysplasia scheme has now been in operation for over
25 years and has recently had some critical appraisal in both the
veterinary and dog press with the advent of hands-free distraction
radiography and PennHIP in the UK. Although the scheme has its
inadequacies it is equally important to look at its achievements and
its role in the future control of canine hip dysplasia (CHD).
The scheme has undoubtedly raised awareness of CHD amongst dog
breeders and has reduced the incidence of pups developing severe
problems at an early age. The Kennel Club will argue that rolling
breed mean scores are reducing annually and therefore the scheme is
working. The accuracy of this statement has to be questioned due to
the bias of non-submissions as there is no compulsion to send in the
radiographs for evaluation.
As CHD is a polygenic developmental condition, identifying the
carriers of the genes is done by using an expression of the genes or
phenotype. The phenotype used by the BVA/KC is a quantitative
evaluation of the degrees of subluxation and development of
secondary bone deposits and remodelling seen on a hip-extended
radiographic view. The strength of this phenotype is that high
scores for either parameter accurately predict the presence of the
CHD genes. However the converse is not true as the radiographic
positioning tightens up the hips reducing the degree of
All of the international CHD schemes basically attempt to predict
the likelihood of an individual developing hip osteoarthritis (OA).
The hip laxity from CHD results in degenerative articular cartilage
changes that can lead to the development of OA, but it is only the
OA changes that are easily detectable.
The BVA/KC scheme quantifies the degree of OA, but as the condition
can be rapidly progressive, the score can not be meaningful as it
will increase with age. The actual presence of OA must surely be a
good predictor of a CHD gene carrier.
The reporting of the results of the BVA/KC is probably meaningless
to most breeders with the only advice given is to breed from dogs
well below the breed mean and this is not even on the certificate.
The response from the BVA chief scrutineer is that it is the owner’s
veterinary surgeon who should give advice on the meaning of the
results! With the greatest respect to my professional colleagues I
suspect that many of us will not feel sufficiently knowledgeable in
the disciplines of genetics and orthopaedics to give good advice and
this direction should come from the BVA on the certificate.
With the current debates on health and breeding within the Kennel
Club it is surely a good time for the BVA to be proactive in
improving their CHD scheme. The inherent problems associated with
false negatives should be recognised and the strength of the scheme,
the accurate identification of poor hips, acted on.
Perhaps the most important parameter is the presence of OA in a
young dog. This needs to be documented on the certificate as either
it being present or not, and not lost in the mumbo jumbo of the
Undoubtedly the BVA/KC scheme is here to stay and it falls upon the
BVA to make it work as well as possible. In the light of the Bateson
report the BVA may have to define suitable breeding stock! Hopefully
the PennHIP scheme will also be adopted in the UK and recognised as
an alternative by the Kennel Club.
A comprehensive list of references can be found at:
Nantwich Veterinary Hospital
Nantwich CW5 5SF