Canine hip dysplasia and the PennHIP method:
Dr. Todd Murphy, DVM
Canine hip dysplasia (CHD) is the most commonly inherited orthopedic disease in dogs. Ultimately leading to hip arthritis, canine hip dysplasia initially causes pain, stiffness, and diminished quality of life as early as 12-16 months of age. Then, as clinical signs progress, severe end stage arthritis results if not treated early in your dog’s life. No medical or surgical cure exists for CHD. Unfortunately, CHD afflicts more than 50% of dogs within some breeds. Large breed dogs are more severely affected from a clinical standpoint as compared to small breed dogs.
In the 1980’s, researchers at the University of Pennsylvania’s School of Veterinary Medicine pioneered a better diagnostic method to assess hip laxity, the key factor in the development of CHD. The hip joint is a ball-and-socket joint, with the ball of the femur (femoral head) fitting into the hip socket (acetabulum). Hip laxity refers to the degree of ‘looseness’ of the ball in the hip socket. Studies have shown that dogs with looser hips (excessive hip laxity) are at higher risk to develop hip dysplasia than dogs with tighter hips (minimal hip laxity).
The research-based hip-screening procedure known as PennHIP has proven to be the most accurate and precise method to measure hip laxity. It can identify as early as 16 weeks of age dogs that are susceptible to developing hip dysplasia. This offers breeders the opportunity to make early decisions on breeding stock, and allows veterinarians to advise pet owners on lifestyle adjustments and preventative strategies to minimize the pain and progression of the disease.
There are two principal innovations in the PennHIP method. FIrst, the dog is positioned on the x-ray table with hips in a neutral orientation, and second, a custom distraction device is applied to reveal the maximum amount to hip laxity. To achieve this, the dog’s muscles are completely relaxed by administering sedation or general anesthesia.
Veterinarians must complete specialized training and quality control exercises before becoming certified to perform the PennHIP procedure.
Dr. Todd Murphy, DVM is a PennHIP certified veterinarian.
A complete PennHIP evaluation includes office consultation, sedation/ anesthesia, and submission of the three PennHIP radiographs to the University of Pennsylvania for evaluation.
PennHIP screening includes three separate radiographs (x-rays): Hip-extended, compression, and distractions radiographs:
Hip extended radiograph
Compression radiographs Distraction radiographs
Your PennHIP veterinarian will submit the three PennHIP radiographs to the University of Pennsylvania for specialized evaluation. A confidential report comprised of the following three key parts will be sent to you and your PennHIP veterinarian:
Distraction index (DI)
The DI is a measure of hip laxity, the inherent distance the ball can be displaced from the hip socket, and is expressed as a number between zero and one. A DI near zero indicates little joint laxity (very tight hips). A DI closer to 1.0 indicates a high degree of laxity (very loose hips). Dogs with tighter hips are less likely to develop hip dysplasia than dogs with looser hips. A threshold level of 0.30 has been identified, below which hip dysplasia is very unlikely to occur.
Arthritis
The PennHIP report also includes an evaluation of the hip-extended radiograph for evidence of arthritis, confirming a diagnosis of CHD. For dogs with evidence of arthritis, your PennHIP veterinarian can explain the disease fully and recommend palliative measures.
Breed Laxity Profile Ranking
Based on the DI, your dog is ranked within its breed. For the dog breeder this ranking helps in the selection of breeding candidates- dogs in the tighter half of the population are recommended for breeding.
By selecting breeding dogs with tight hips (lower DI), meaningful progress toward better hips can be made within a few generations.
PennHIP is the most accurate hip screening method available and can be safely performed on dogs as young as 16 weeks of age. An early estimate of dog’s hip integrity is invaluable, wether the dog’s intended purpose is for breeding, for working, or as a family pet.
For Breeders
Information compiled in PennHIP’s international database permits informed selection of breeding stock based on hip tightness relative to other members of the same breed.
Breeders can reduce the incidence and severity of CHD in future generations of dogs by applying selection pressure towards tighter hips. Among current hip screening methods, PennHIP has the highest heritability value to bring about these genetic changes.
For pet owners
If your dog is identified to be at risk for CHD, your PennHIP veterinarian can recommend, at an early age appropriate strategies (diet, medications, and/ or activity) to delay or diminish the ultimate course of disease.
Dr. Todd Murphy, DVM is a certified PennHIP veterinarian and has worked closely with Dr. Gail Smith, developer of the PennHIP method, while completing his surgical residency at the University of Pennsylvania’s School of Veterinary Medicine.
Dr. Todd Murphy, DVM is responsible for research into feline hip dysplasia and evaluation of over 200 Maine Coon’s using the PennHIP method in cats as well. Yes, cats do get hip dysplasia too.
For more detailed information you may contact Dr. Todd Murphy, DVM or visit the PennHIP website at www.pennhip.org
Contact Dr. Todd Murphy:
cell (615) 943-5669