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rec.pets.dogs: PennHip FAQ
Last-modified: 13 May 1997
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PennHIP FAQ Sheet
Questions and Answers about PennHIP
A New Scientific Method for Early Screening for Canine Hip Dysplasia
* What Exactly Is PennHIP?
* How Was PennHIP Developed?
* How Does PennHIP Differ from Evaluation Methods Which Use the Hip
* What Happens to My Dog During a PennHIP Evaluation?
* What Is the Cost of Having My Dog Evaluated?
* Is PennHIP Going To Replace Other Commercially Available Systems?
* Will AKC and Other Breed Registration Organizations "Recognize"
* Are the Results Confidential?
* How Does This Benefit Me as an Owner or Breeder of Dogs?
* How Can I Get the Name of a PennHIP Veterinarian or Get Answers to
Canine Hip Dysplasia (CHD) is the most common, heritable orthopedic
problem seen in dogs. It affects virtually all breeds of dogs but is
especially problematic in large and giant breeds. Clinically, the
disease manifests itself in one of two ways:
1. a severe form that typically afflicts the younger animal and is
usually characterized by marked pain and lameness, or
2. a more chronic form with more gradual onset of clinical signs such
as mild intermittent pain, stiffness and restricted range of
motion in the hips as the dog ages. In many cases, the chronic
form may be clinically silent.
Breeders and veterinarians have long sought a reliable method to
determine the likelihood of a dog developing CHD and passing that
genetic trait to any offspring. It was generally recognized that the
current diagnostic methods of hip evaluation were associated with
disappointing progress in reducing the frequency of CHD. In 1983, Dr.
Gail Smith, a veterinary orthopedic surgeon and bioengineer from the
University of Pennsylvania School of Veterinary Medicine, began to
actively research and develop a new scientific method for the early
diagnosis of Canine Hip Dysplasia. Research in his laboratory resulted
in a diagnostic method capable of estimating the susceptibility for
CHD in populations of dogs as young as sixteen weeks. The method has
shown distinct advantages over the standard CHD diagnostic method that
evaluates dogs at two years or older. The university of Pennsylvania
Hip Improvement Program (PennHIP) was founded as an extension of Dr.
Smith's laboratory research. Below are answers to some commonly asked
questions about the PennHIP method.
What Exactly Is PennHIP?
PennHIP is a scientific method to evaluate a dog for its
susceptibility to develop Hip Dysplasia. The radiographic procedure
involves a special positioning of the dog so that the dog's "passive
hip laxity" can be accurately measured. In simple terms, passive hip
laxity refers to the degree of looseness of the hip ball in the hip
socket when the dog's muscles are completely relaxed. Research has
shown that the degree of passive hip laxity is an important factor in
determining susceptibility to develop Degenerative Joint Disease (DJD)
later in life. Radiographic evidence of hip DJD, also known as
osteoarthritis, is the universally accepted confirmation of CHD.
PennHIP is being marketed by International Canine Genetics, Inc. (ICG)
of Malvern, PA.
How Was PennHIP developed?
The development of PennHIP has involved multiple disciplines including
biomechanics, orthopedics, clinical medicine, radiology, epidemiology
and population genetics. The first phase of development involved
sophisticated biomechanical testing to determine the optimal patient
position for measuring hip laxity. By monitoring passive hip laxity in
dogs as they matured, it was discovered that hip laxity was the
primary factor in the development of the DJD characteristic of CHD.
That is, the radiographic expression of DJD was statistically
significantly correlated with the degree of measured passive hip
laxity. In addition, the CHD prediction was shown to be acceptably
accurate in populations of puppies as young as sixteen weeks of age.
Moreover, the correlation between passive hip laxity and subsequent
hip DJD was shown to increase over the four-month figures when hips
were evaluated at six months and twelve months of age. In the same
studies, it was shown that there was no statistically significant
correlation between laxity and DJD when the standard hip extended
position was used. In addition, no other method used to evaluate for
CHD has undergone similar rigorous testing through controlled
scientific studies to determine diagnostic accuracy.
How Does PennHIP Differ from Evaluation Methods Which Use the Hip Extended
PennHIP differs in some very fundamental and important ways. First,
PennHIP was developed and tested following strict scientific protocol
and the results of these studies have been published (and continue to
be) in peer-reviewed, scientific journals. More than a decade of
research and analysis has produced a body of information in support of
PennHIP's effectiveness. As with all diagnostic tests, PennHIP's
accuracy is not 100 percent, but in direct comparisons it is far
superior to any other available diagnostic method. Second, passive hip
laxity is objectively measured and the resulting Hip Evaluation Report
is not issued in a pass/fail framework. PennHIP specifically measures
passive joint laxity and includes the quantitative measurement in its
report. Based on the degree of laxity, the individual dog is then
ranked relative to other members of the same breed. (Note: Breed
specific rankings are given when there are twenty or more evaluations.
If there are fewer than twenty evaluations - ranking is made to the
general dog population.) For Example, a dog receiving a ranking in the
70th percentile means that thirty percent of its breed members have
hips that are tighter. This allows breeders to easily identify those
animals with tighter hips within each breed. As shown in our studies,
dogs with tighter hips are less likely to develop CHD and pass that
genetic tendency on to future generations. Third, because PennHIP is
measuring maximal passive hip laxity, the position of the patient is
very different from the hip-extended position. The hip-extended
position has been used for more than thirty years to screen hips for
either DJD, laxity or both. Laboratory studies, however, have
indicated wide diagnostic variability among radiologists in
interpreting this view. Further, through biomechanical testing, the
hip-extended view was found to mask the underlying true joint laxity
and through direct comparison, the predictive value for CHD was shown
to be inferior to the PennHIP procedure. Most importantly, the
heritability of the diseased phenotype scored in the hip-extended view
has not been studied in most breeds of dogs. A knowledge of
heritability is critical to determine whether the selection pressure
will produce genetic change. Estimates for the heritability of passive
hip laxity drawn from analysis of full pedigrees for the breeds
examined thus far in the studies show high values (for German Shepherd
Dogs, heritability = 0.61). Fourth, the PennHIP method is based on
strict quality control. To take PennHIP radiographs, veterinarians
must undergo training and a certification process to demonstrate
competency. The data generated from PennHIP undergoes regular review
and statistical analysis so that useful information, by breed, is
available to judge progress toward reducing CHD. For optimal validity,
it is mandatory that all PennHIP radiographs be submitted for analysis
and inclusion in the PennHIP database. This policy eliminates the
practice of prescreening radiographs and sending only the best for
evaluation, resulting in biased hip data for any given breed.
What Happens to My Dog During a PennHIP Evaluation?
To obtain diagnostic radiographs, it is important that the patient and
the surrounding hip musculature be completely relaxed. For the comfort
and safety of the animal, this required sedation, however some
veterinarians prefer general anesthesia. Typically, three separate
radiographs are made during an evaluation. The first is a compression
view where the femurs are positioned in a neutral, stance-phase
orientation and the femoral heads are pushed fully into the sockets.
This helps show the true depth of the hip socket and gives an
indication of the "fit" of the ball in the socket. The second
radiograph is the distraction view. Again, the hips are positioned in
a neutral orientation and a special positioning device is used to
apply a harmless force to cause the hips to displace laterally. This
position is the most accurate and sensitive for showing the degree of
passive laxity. Passive laxity has been shown to correlate with the
susceptibility to develop DJD. A hip extended view is also included
for the sole purpose of examining for any existing joint disease such
as osteoarthritis. The PennHIP procedure has been safely performed on
thousands of patients.
What Is the Cost of Having My Dog Evaluated?
The total fee for a PennHIP evaluation is determined by the
veterinarian providing the service. It is important to remember that
the total service includes sedation/anesthesia, three radiographs,
office consultation and all charges associated with mailing and film
evaluation. You will not find it necessary to write a separate check
for evaluation fees or mail your dog's films. The veterinarian
performing the procedure is responsible for payment and film
submission. The film evaluation charge (currently $25.00) will be
included in the total cost of a PennHIP evaluation.
Is PennHIP Going To Replace Other Commercially Available Systems?
As technology advances, the veterinary professional community will
offer and utilize improved methods of disease diagnosis. The dog
breeding community will also endorse those methods that help them
achieve their goals of reducing the frequency of hip Dysplasia in dogs
while maintaining other desirable traits and features. The PennHIP
technology and research have been and will continue to be, fully
presented to the veterinary medical community for its review. PennHIP
has been received enthusiastically as a major step toward reducing the
frequency of CHD. We encourage and welcome continued scientific
examination and comparison of PennHIP to any available or new methods
of canine hip Dysplasia diagnosis.
Will AKC and Other Breed Registration Organizations "Recognize" PennHIP?
ICG is working with many organizations to present the PennHIP
technology and the positive impact it holds for reducing Canine Hip
Dysplasia. It is conceivable that at some point a PennHIP reference
might be included as part of the dog's registry information. However,
all hip evaluation reports are considered confidential medical
information and are released only to the PennHIP veterinarian and the
owner of the dog (unless the owner requests otherwise).
How Does This Benefit Me as an Owner or Breeder of Dogs?
Scientific data confirms that the PennHIP method surpasses other
diagnostic methods in the ability to accurately predict susceptibility
to developing CHD. The method can be performed on dogs as young as
sixteen weeks of age compared with two years using the standard
technique. The ability to receive an early estimate of a dog's hip
integrity is important whether the dog's intended purpose will be for
breeding, for working or as a family pet. The data generated by
PennHIP will allow breeders to confidently identify the members of
their breeding stock with the tightest hips. The PennHIP
interpretation will also permit breeders to assess the progress they
are making with their breeding program as they strive to reduce the
amount of hip laxity in their dogs. Pet owners are able to assess
their pet's risk of developing CHD, and make lifestyle adjustments for
their dog, if necessary, to enhance the quality of their pet's life.
How Can I Get the Name of a PennHIP Veterinarian or Get Answers to
To obtain the name of a veterinarian near you who is trained and
certified to perform the PennHIP procedure, call ICG at
1-800-248-8099. If there is not a veterinarian near you presently,
additional veterinarians are being trained throughout the country. If
your veterinarian would like to learn more about PennHIP, please have
him/her contact ICG directly.
For more information
or inquire via email to ICG at
International Canine Genetics
271 Great Valley Parkway, Malvern, PA 19355
Internet Version kept by Bill Faulk,