OFA vs PennHIP: two ways to screen a dog's hips
Hip dysplasia is the most screened condition in dogs, and there are two respected ways to test for it. They measure different things, at different ages, with different results. This VerifiedStuds guide compares them, so you can read a stud's hip report with confidence.
OFA
PennHIP
What it measures
The shape and fit of the hip joint
How loose the hip joint is
X-ray views
One, with legs extended
Three, including a distraction view
Sedation
Not required, though often used
Deep sedation or anesthesia required
Who takes the x-rays
Any veterinarian
A PennHIP-trained veterinarian
Earliest result
Preliminary from 4 months; final at 24 months
From 16 weeks
Result
A grade, from Excellent to Severe
A distraction index and a breed percentile
Both are accepted on VerifiedStuds. In addition, OFA records PennHIP results in its database, and most parent clubs accept either one.
The Orthopedic Foundation for Animals has graded hips since 1966. A vet takes one x-ray with the dog on its back and its hind legs stretched out. Then three independent radiologists score the image, and OFA issues a consensus grade.
There are seven grades. Excellent, Good and Fair are normal, and they receive an OFA number. Borderline sits in the middle. Mild, Moderate and Severe are dysplastic. Read OFA hip and elbow grades explained for what each one means.
OFA gives a final result only at 24 months or older. However, it offers preliminary evaluations from four months, which many breeders use for an early look.
PennHIP was developed at the University of Pennsylvania. It rests on one finding: loose hips are the best early predictor of arthritis. So the method measures looseness directly.
With the dog under deep sedation, a trained vet takes three x-rays. One of them uses a device that gently pushes the hips apart. From that image, the service calculates a distraction index, or DI, between 0 and 1. A lower number means a tighter hip. In general, a DI under about 0.30 carries a low risk of arthritis.
The report also ranks the dog against others of its breed. As a result, breeders can aim for dogs in the tighter half of the breed.
Age. PennHIP gives a usable result from 16 weeks, while OFA's final result waits until two years.
Objectivity. PennHIP produces a measured number. In contrast, OFA grades are expert opinions, although three radiologists must agree.
Familiarity. OFA grades are simple, and everyone in the dog world understands them. A DI needs more explanation.
Access and cost. Any vet can take an OFA film, and the dog can often stay awake. PennHIP needs a certified vet and sedation, so it usually costs more.
Pass or fail. OFA gives a clear normal or abnormal result. PennHIP gives no pass mark, only a comparison with the breed.
Prices vary by clinic and region. As rough estimates, OFA hip x-rays often cost $150 to $400 at the vet, plus OFA's own fee. PennHIP commonly runs $400 to $800, because it includes sedation, three views and the report. Ask your vet for a quote.
Many careful breeders use both. For example, they run PennHIP early to decide which puppies to keep, then add OFA at two years for the public record. If you can afford only one, follow your breed's parent club, since some name a preference. Our health testing guides list what each club asks for.
Remember that neither test is a guarantee. Hip dysplasia involves many genes, plus growth rate, weight and exercise. Therefore, the hips of parents, siblings and earlier puppies matter as well as the stud's own.
Ask which system was used, and at what age.
Check OFA results under his registered name in the public OFA database.
Ask for the PennHIP report itself, which shows both hips and the breed percentile.
Treat preliminary OFA results as a good sign, not a final clearance.
Ready to compare? Then find a health-tested stud, and check prices in the stud fee guide. Stud owners can list their stud free. This page is general information, not veterinary advice.
Is PennHIP better than OFA?
Neither is simply better. PennHIP is more objective and works earlier, while OFA is cheaper, widely understood and gives a clear grade.
At what age can a dog have PennHIP?
From 16 weeks. OFA final results need a dog of at least 24 months.
What is a good PennHIP score?
Lower is better. A distraction index under about 0.30 is tight, and breeders also aim for the better half of the breed.
Does OFA accept PennHIP results?
Yes. OFA can record a PennHIP report in its database, and most CHIC programs accept either test.
Does a good hip score guarantee healthy puppies?
No. It improves the odds, but hip dysplasia depends on many genes and on how a puppy is raised.
Sources: Orthopedic Foundation for Animals, hip dysplasia, AIS PennHIP, American Kennel Club, guide to responsible dog breeding. Cost figures are estimates.
Every profile shows which hip test he has, with the result.