PennHip VS. OFA – which is best?
PennHIP and OFA screening are the primary methods of assessing hip health for breeders. PennHIP screening measures joint laxity (known as the distractive index) as well as the conformation of the hip joint, but only gives a percentile index for joint laxity because evaluating hip conformation is somewhat subjective and so more difficult to score without bias. The higher the distractive index, the laxer the joint, and thus an increasing probability of developing degenerative joint disease known as hip dysplasia. OFA evaluates hip conformation and looks for signs of hip dysplasia or arthritis and gives a grade based on 3 radiologists’ subjective interpretation.
OFA films can be taken for a preliminary assessment after 1 year of age, but a permanent grade is not possible until they are at least 2 years of age. This ensures full hip development and is the fairest age to assess true hip conformation. PennHIP films can be taken any time after 4 months of age, as it has been shown that hip laxity doesn’t change after 4 months of age. When taking PennHIP films, the OFA view is also taken, and joint conformation assessed.
OFA results are reported as Excellent, Good, Fair, Poor or Dysplastic. PennHIP results are a reported as a percentile of the distractive index compared to all other dogs of the same breed that have been tested. With OFA, owners can choose to report their results on the public website or not, so there is likely some bias when comparing within a breed, since it is possible to exclude those animals that are poor or dysplastic if the owner chooses. With PennHIP, all results are reported, good or bad, so comparing to all other scores gives you a good sense of where you dog lies amongst breed counterparts.
OFA recommends films be taken with sedation or anesthesia because the muscles being tense can affect positioning and the way the hip sits in the joint and this may affect the results. Even a dog that is being really good lying on its back will have muscle rigidity that may affect the grade. While OFA recommends sedation or anesthesia, they will allow films to be obtained in an awake dog as well. PennHIP requires general anesthesia.
The best option is to use both OFA and PennHIP screening. This gives the breeder the most information about hip conformation and laxity and helps determine which animals are best to keep in the breeding pool. Not all dogs with poor hip conformation or with lax hips will develop hip dysplasia or arthritis, but the poorer the conformation or the greater the distractive index the greater the likelihood. This information can then be used to help select a mate for the animal in question that will best improve hip health.
For more information on PennHIP or OFA films, please call our office and one of our doctors would be happy to speak to you.
Courtesy of Cheryl Lopate at REPRODUCTIVE REVOLUTIONS