The PennHIP Procedure
The PennHip - Misconceptions and Misinformation -
Fred Lanting
Because osteoarthritis commonly
causes pain and discomfort in the affected joints, the dog with CHD often
has impaired mobility and a diminished quality of life. Therefore,
any method that objectively measures hip joint laxity may be helpful in evaluating
a dog’s risk for developing osteoarthritis and CHD. This information
would assist the dog owner or breeder in deciding which animals not to breed
as well as in selecting the best individual animals for breeding. Before
we go further in this discussion of PennHIP, there are a few terms that are
important to know. Take a look at the Definitions below and refer to
them if you get confused.
The ventrodorsal (front to back), hip-extended (legs pulled straight rearward)
radiographic view as approved by the American Veterinary Medical Association
in 1966 has been a standard for positioning of the dog on the x-ray table.
The radiograph needs to be taken with the dog under sedation or anesthesia
for proper and consistent positioning. If the positioning is not correct,
the asymmetrical images of the hip joints will make accurate interpretation
nearly impossible. This traditional and still widely accepted method
of evaluating hip structure is used by many hip screening programs throughout
the world, including Orthopedic Foundation for Animal (OFA), the Institute
for Genetic Disease Control in Animals (GDC) and PennHIP. The OFA system
and registry has been one strategy attempting to improve the knowledge base
and selection process for breeders interested in eliminating CHD from a
breed. Many breeders and veterinarians agree that the incidence of CHD has
noticeably decreased over the years since it was first described, partly
because awareness of CHD among pet owners and breeders has reached fairly
high levels. For years the OFA protocol has been the most commonly utilized
method of screening and certifying dogs as having normal or dysplastic hips.
Unfortunately, subjective variables can enter into the OFA evaluation process.
Although preliminary radiographs can be revealing, a potential drawback with
the OFA protocol is the fact that for certification and definitive evaluation
a dog must be 24 months of age or older at the time the hip radiographs are
taken. Additionally, occasional criticism is heard that some veterinarians
unknowingly affect the evaluation of the radiograph by their subjective positioning
of the dog at the time the radiographs are taken; plus individual interpretation
of what is visible on the radiograph is sometimes challenged. There
exists the disappointing fact that outright fraud has occurred by unscrupulous
individuals who misrepresent a radiograph as being of an animal other than
the one actually radiographed. | It is especially important to perform
a Distraction Index (DI) on dogs that have normal appearing hips on the ventrodorsal
extended view, such as appears to be the case in the image on the right.
Dogs that are diagnosed as having excellent hips on the traditional
VD view can actually have a huge amount of laxity. PennHIP's recommendation
is to limit breeding to those dogs that have normal appearing hips
on the VD hip extended view and that also have a DI at the breed's mean laxity
or tighter. |
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Only certified individuals who have undergone special training and have
successfully demonstrated their expertise in the technique are permitted
to perform PennHIP procedures. Since both PennHIP and OFA use the ventrodorsal,
hip-extended view, your PennHIP certified veterinarian can make a copy of
the hip-extended radiograph for submission to the OFA at the time your dog
has the PennHIP procedure. You do not have to abandon OFA opinion nor schedule
a separate appointment for an additional radiograph.