PennHIP stands for the University of Pennsylvania Hip Improvement Program. After alot of research and talking to many vets in Australia (both pennHIP registered and those that were not), we have decided to follow the pennHIP system for scoring hips within our own breeding program. I am a nurse who has taught x-ray interpretation to nursing students for many years and am convinced this is the best method that breeders should be adopting. Sharon Mallinson. The following has been compiled from information on the University of Pennsylvania website. (sourced June 2006) History of PennHIP In 1983, Dr. Gail Smith from the University of Pennsylvania School of Veterinary Medicine conceived and developed a new scientific method for the early diagnosis of canine hip dysplasia (CHD). Research conducted in his laboratory proved the diagnostic method to be capable of estimating the susceptibility for CHD in dogs as young as sixteen weeks of age. In 1993, Dr. Smith established PennHIP, a cooperative scientific initiative, to serve as a multi-center clinical trial of the new hip dysplasia diagnostic technology. The program was successful and quickly grew beyond the capacity and purpose of a university research laboratory. Initially, the University of Pennsylvania licensed PennHIP to outside biotech companies in order to make the technology available for widespread public use and to allow Dr. Smith and his colleagues to continue their research at the School of Veterinary Medicine. PennHIP has recently been reacquired by the University of Pennsylvania and is now a not-for-profit organization. PennHIP is a network of veterinarians trained to perform the PennHIP methodology properly and, perhaps most importantly, it is a large scientific database that houses the PennHIP data. The radiographs are made by certified PennHIP members worldwide and are sent to the PennHIP analysis center for evaluation. The resulting data is stored in the database, which is continually monitored as it expands. As more information becomes available, the PennHIP laboratory is able to obtain more precise answers to questions about the etiology (cause), prediction and genetic basis of CHD. The PennHIP laboratory publishes its findings in scientific journals. Published information is disseminated to all PennHIP members; it is also shared with interested breed clubs and routinely appears in publications within the dog fancy. What is Canine Hip Dysplasia (CHD)? In 1966, Henricson, Norberg and Olsson refined an earlier definition of CHD describing it as: “A varying degree of laxity of the hip joint permitting subluxation during early life, giving rise to varying degrees of shallow acetabulum and flattening of the femoral head, finally inevitably leading to osteoarthritis.” Today, the general veterinary consensus is that hip dysplasia is hip joint laxity resulting in osteoarthritis. The Development of CHD It is generally agreed that hip joint laxity is somehow related to the development of degenerative joint disease (DJD). However, prior to the research conducted at the University of Pennsylvania, there existed little or no scientific evidence to bolster this empirical association. The magnitude of hip laxity had not been correlated with the presence or the extent of DJD. The science behind the PennHIP method has shown unequivocally that hip joint laxity is the most important risk factor for the development of DJD. CHD is a developmental disease meaning that it is not present at birth, but develops with age. CHD Diagnosis CHD in its severest form can be diagnosed by clinical signs, but it usually requires radiographic evidence of hip joint laxity and/or the appearance of DJD to arrive at a definitive diagnosis. An affected dog may have one or any combination of the following clinical signs: Presentation: 5 months to 12 months for the severe form of hip dysplasia; later for the chronic form Abnormal Gait Bunny-hopping When Running Thigh Muscle Atrophy (loss of muscle mass) Pain Low Exercise Tolerance Reluctance to Climb Stairs Audible “click” When Walking Increased Intertrochanteric Width (“points of hips” are wider than normal) Clinical signs alone do not necessarily mean that a dog has hip dysplasia, other conditions of the hip can mimic CHD. A radiograph is essential for a more accurate assessment of the dog’s hip joint integrity. The PennHIP Method Consists of three separate radiographs. The distraction view and compression view, developed by Dr. Smith, are used to obtain accurate and precise measurements of joint laxity and congruity. The hip-extended view is used to obtain supplementary information regarding the existence of degenerative joint disease (DJD) of the hip joint. Distraction view PennHIP state “on average the distraction view has been shown to reveal 2.5 – 11 times more hip laxity (depending on breed) than the hip-extended view. Also the PennHIP method can measure the laxity of a hip joint with greater precision than the hip-extended method……..The looser the joint on the distraction view, the greater is the chance that the hip will develop DJD. Compression view The compression view is used to determine the “goodness of fit” of the femoral heads into the acetabula. In a hip with DJD, the remodeling that occurs in the acetabulum and/or the femoral head, will often result in an ill-fitting “ball” and “socket” Hip-extended view. (used in the AVA Method) In the hip-extended view, the femur is pulled into extension. The fibrous elements of the joint capsule get “wound up” so to speak, so that the resulting tension serves to drive the femoral head into the acetabulum (socket). This explains why the measurable joint laxity on the distraction view is always greater than the measurable laxity from the hip-extended view. The hip-extended view tends to mask true hip joint laxity because the joint capsule is wound up into a tightened orientation when the hips are extended. It follows that a loose-hipped dog, could falsely be considered to have “tight” or “normal” hips according to the hip-extended radiograph. Such a dog would likely be approved for breeding and therefore could pass this loose-hipped trait onto its offspring. To see how joint laxity is actually measured and interpreted, go to the PennHIP website Research section. For further information on PennHIP links are provided from our links page to University of Pennsylvania PennHIP