PennHIP vs OFA: Which Hip Screening, at What Age, and What It Does to Your Insurance

OFA and PennHIP are not two versions of the same test. OFA grades how a hip looks on one extended-leg X-ray, and its final grade needs a dog of at least 24 months. PennHIP measures how far the ball can be pulled out of the socket, on three films, from 16 weeks, and reports a number against other dogs of the same breed. When 439 dogs had both, 80% of the ones OFA graded normal had a distraction index of 0.30 or higher, the level above which arthritis risk begins to rise. So if you want a certificate, use OFA at two years. If you want an answer you can act on while your dog is still a puppy, and the earliest preventive surgery closes at about 20 weeks, use PennHIP. And whichever you choose, enroll in pet insurance before the films are taken, not after, because a laxity score is a dated document that says exactly what a pre-existing clause is written to find.

What each test actually measures#

If you have the two program pages open in two tabs a few days before a vet appointment that will offer one of them, you will have noticed that neither page makes the difference plain. Here it is in one table, every cell read at source on 8 September 2026 unless a study is named.

The line that matters most is the first one. The OFA film is taken with the legs pulled straight and rotated, a position that can seat a loose femoral head into its socket. PennHIP adds a view in which the joints are deliberately levered apart, so the amount of play is the measurement rather than something the position hides. Neither test is, on its own, a diagnosis in a four-month-old. Both grade risk, an OFA preliminary's dysplastic grades are confirmed at two years most but not all of the time, and the rest of this page is about how well each predicts.

How much do the two tests disagree?#

This has been measured directly, in the one way that settles it: the same dogs, the same day, both tests. Between 1987 and 2008, 439 dogs of at least 24 months had PennHIP radiography under sedation, and the hip-extended view from the same session was submitted to OFA for grading.^[8]

The authors' conclusion was that dogs judged phenotypically normal by the OFA harboured clinically important passive hip laxity, and that OFA scoring of the hip-extended film underestimated susceptibility to osteoarthritis.^[8] Read the second row again, because Good was the largest group in the study. Four in five of those dogs had hips loose enough to sit above PennHIP's own risk cut-off.

That is not a flaw in the OFA's reading. Three radiologists looked at a film and reported, accurately, what a hip-extended film shows. An OFA Good is an accurate answer to a question you did not ask. The question you asked, if you own a young dog and want to know what is coming, is how loose the joint is, and a hip-extended film was never designed to say.

One fairness note the table owes the OFA. The study's dogs were dogs whose owners had chosen PennHIP screening, not a random sample of the OFA database, and the 0.30 cut-off is PennHIP's own threshold, described on its program page as a point below which hips have very low susceptibility to osteoarthritis.^[9] The group that built PennHIP also wrote the comparison. We found no published result that contradicts it, and no independent replication of it either.

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Why the age matters more than the test#

If your dog is already two, the choice is mostly about what you want the paper for. If your dog is a puppy, the choice is about time, and the two programs run on different clocks.

What a young grade is worth. The OFA's own reliability study followed 2,332 Golden Retrievers, Labradors, German Shepherds and Rottweilers who had a preliminary evaluation between 3 and 18 months and a definitive one after 24. A preliminary Excellent stayed normal at two years 100% of the time, a Good 97.9%, a Fair 76.9%. A preliminary Mild dysplasia was confirmed 84.4% of the time, a Moderate 97.4%. For preliminaries graded normal, agreement with the final grade rose with the puppy's age: 89.6% at 3 to 6 months, 93.8% at 7 to 12, 95.2% at 13 to 18, and the abstract reports the same direction for dysplastic preliminaries without breaking out the figures.^[10] Those are good numbers at the ends of the scale and weak ones in the middle, which is where a worried owner's puppy usually sits: a preliminary Fair stayed normal 76.9% of the time across the whole 3-to-18-month pool, which is not the certainty a certificate implies.

Why the number holds earlier than the grade. In a three-year prospective study of 142 large-breed dogs radiographed at 4, 6, 12, 24 and 36 months, the distraction index was far more consistent from one age to the next than the subjective seven-point score, and the authors wrote that the error in the subjective scheme questions its predictive use, particularly before the age of two years.^[11] In a smaller 2022 cohort, a distraction index taken at a mean of 6.6 months correlated with the adult Norberg angle at r = −0.66.^[12] And in the 151-dog study that first modelled the risk, the distraction index predicted later joint disease at 4, 12 and 24 months, while the Norberg angle, the laxity measure taken from the standard hip-extended film, did not predict it at any age.^[13]

The deadline neither program advertises. The earliest operation that aims to prevent dysplastic arthritis rather than repair it, juvenile pubic symphysiodesis, and the only one with a window this young (pelvic osteotomies come later, at several months, and are a different decision), is performed on puppies at about 15 to 20 weeks; the randomized study behind it found better hip conformation when it was done at 15 weeks than at 20.^[14] PennHIP's earliest age is 16 weeks. The OFA's earliest preliminary is 4 months, read by one radiologist, and its certification is at 24 months. Put those three dates on one line and the decision is mostly already made for you: a test whose answer arrives at two years cannot inform a surgery that has to happen by twenty weeks. If your puppy is under four months and from lines you cannot vouch for, the question is not which test. It is whether there is a PennHIP-certified vet within driving distance in the next three weeks, and the program keeps a locator for exactly that.^[7]

A puppy with loose hips at four months usually runs, jumps and lands like one with tight hips. Not always: a vet's hands can find laxity in some puppies, the Ortolani sign, and the puppies in the JPS trial had measurably increased hip laxity at 15 weeks, with palpation and pain scores recorded before surgery.^[14] But nothing in the household shows it. That is not the dog hiding anything; nothing has gone wrong yet. The film and the examining hand are the only places the difference exists, and the certificate that would show it arrives more than a year and a half after the window to act on it has closed.

“Because your dog can't tell you how much pain he or she is in.”

German Shepherds: the numbers in one place#

Among the searches that reach our German Shepherd hip dysplasia guide are requests for the data as graphs or tables rather than prose. Here is every figure we have verified at source, in one table, with the study it came from.

Two rows in that table contradict each other on purpose, and the contradiction is the breed's whole problem. German Shepherds had the tightest hips of the four breeds on average, and the highest probability of joint disease. The study's authors described the breed's risk curve as shifted to the left: for any given distraction index, a German Shepherd was more likely to have joint disease than a Golden, a Labrador or a Rottweiler, and they speculated about the breed's lower pelvic muscle mass and its flexed, crouched stance converting passive laxity into functional laxity under load.^[17] An earlier comparison against 74 Rottweilers found the same thing: German Shepherds carried a significantly greater risk of joint disease at the same laxity.^[18]

The practical reading: a German Shepherd's distraction index needs to be judged against the German Shepherd threshold of 0.28, not the general 0.30, and a percentile within the breed, which PennHIP reports, is worth more than the raw number. A 0.35 that would be unremarkable in a Labrador is over the line in this breed.

One search that reaches this site asks whether a German Shepherd's sex changes life expectancy with hip dysplasia. No study we can find measures life expectancy in dysplastic German Shepherds by sex, so the honest answer to "does gender affect it" is that the outcome nobody has measured cannot be quoted, and the outcome that has been measured, radiographic joint disease, did not vary by sex.

What the result does to your insurance#

We have read the policy documents on the hip dysplasia insurance page, and one clause there rewrites this whole decision. Spot's sample policy counts a condition as occurring when signs "would have been detectable by a routine physical veterinary exam," observed or not.^[19] That definition does not need a limp. A distraction index of 0.55 on a dated report, in a dog with no symptoms, is the most detectable thing there is.

The test that serves the breeder and the surgeon can therefore cost the buyer her claim. The sequence that protects you is:

1. Enroll first. Hip waiting periods across the brands we read run from 14 days at Spot^[19] to 12 months at Healthy Paws,^[24] with Embrace's orthopedic wait at 180 days,^[23] and every one of them is measured from the policy start date, not from the diagnosis.
2. Let the hip waiting period run out before any hip film is taken, including an OFA preliminary. Where the insurer offers a waiver, use it: Embrace's page says an orthopedic exam in the first 14 days that finds nothing cuts its 180-day wait to 14 days, and a clean exam later cuts it to the exam date. That exam is hands and a history, not a distraction film; ask, in writing, whether a radiograph taken at the same visit would count as the exam or as a finding.
3. Ask the insurer in writing, before screening, how a laxity index or a preliminary grade with no clinical signs would be treated. Keep the answer.
4. Screen.

If the juvenile surgical window makes that order impossible, because your puppy is 14 weeks old and a 180-day orthopedic wait will not clear until she is nine months and the insurer offers no waiver exam, then you are choosing between the surgery and the coverage, and that is a real choice to make with the numbers in front of you rather than one to discover at claim time. A screening you delayed for the policy's sake cannot be un-delayed for the dog's.

Neither test is a diagnosis, and both have a floor#

It is worth saying plainly what a good result does and does not buy. In the 15,742-dog analysis, not every dog with the loosest hips, an index above 0.7, developed joint disease within the study's age range, and the authors said a tight hip carries a small but finite probability of disease.^[17] Rottweilers had a flatter curve than the other breeds, which the authors read as either a genuine breed difference or a limit of the model. PennHIP itself recommends averaging repeated evaluations where possible for a more reliable estimate.^[3]

And the OFA's grade, for all the above, is the document the breed clubs and most breeders' contracts run on, is read by three radiologists rather than one, and is the cheaper submission. If what you need is a hip on the record at two years, it is the right instrument for that job, and nothing in this article says otherwise.

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What to buy: not the test, the scale#

Nothing on this page is a product, and we are not going to pretend the screening decision needs one. But there is one purchase that follows honestly from the evidence on hips, and it costs eleven dollars.

The feeding intervention with the strongest controlled-trial evidence for reducing hip dysplasia is restriction, and the trial is worth describing exactly. Forty-eight Labrador Retrievers were paired at six weeks; from eight weeks, one dog in each pair was fed 25% less than whatever its pair-mate ate freely. At two years, by the OFA method, 7 of the 24 restricted dogs were dysplastic against 16 of the 24 free-fed dogs.^[20] Followed for life, the restricted group's median age at first radiographic hip osteoarthritis was 12 years; the free-fed group's was 6.^[21] One breed, one colony, one research group; it has not been repeated, because a lifelong paired-feeding trial in dogs is not something anyone is likely to run again. It is still the strongest result anywhere in this subject.

That intervention was a weighed ration, every meal, for years. Most households measure with a cup, and the cup has been tested: 100 owners given a dry-food measuring cup, a graduated liquid cup or a commercial scoop, and asked to measure a quarter, half and one cup of kibble, ranged from 47.83% under to 152.17% over against a gram scale.^[22]

The free alternative comes first. Any gram scale already in the kitchen does this. We have not used this particular unit; it is carded for its 1 g resolution, its tare button and its price, and the product page says so. Weighing the dog monthly at the clinic is usually free and tracks the outcome. What the scale cannot do is choose the amount: "25% less" was 25% less than a free-fed littermate, not a number you can lift from a bag, and the target is a lean body condition score set with your vet. The scale is how the number you agree on stays the number.

What to do this week#

Under 16 weeks, large breed, lines you cannot vouch for. Find out today whether a PennHIP-certified vet is within reach, and book for the week she turns 16 weeks. If insurance matters to you, buy it this week, read its hip waiting period, and understand that you may be choosing between the two.

16 weeks to 6 months. The surgical window is closing or closed, but the number is still worth having: it tells you how hard to work on weight, which floors to cover, and whether the signs by age are worth watching for at two rather than at seven. Ask for PennHIP if it is available; an OFA preliminary is a reasonable second choice, with the mid-scale grades read as uncertain.

6 to 24 months. Either test now gives a usable answer. If you want the record, wait for the OFA final at 24 months. If you want to act, do not wait; the delay is the whole disease.

Already screened, result loose. Weigh the food from tonight. Read what actually helps, stage by stage and the surgical options with the number in hand rather than a guess.

The delay this site keeps writing about is usually the months between a quiet sign and its name. Here the sign is on a film that can be taken at sixteen weeks, and the delay is choosing the test whose answer arrives at two years.

Sources#

1. Antech Diagnostics. "What is PennHIP." antechdiagnostics.com — read 8 September 2026: three separate radiographs, the distraction view, the compression view, and the hip-extended view.
2. Orthopedic Foundation for Animals. "Hip Dysplasia." ofa.org — read 8 September 2026: the seven grades and their descriptions.
3. Antech Diagnostics. "PennHIP FAQ." antechdiagnostics.com — read 8 September 2026: reliably performed as young as 16 weeks; heavy sedation or general anesthesia required; fee determined by the veterinarian providing the service; laxity reported relative to other members of the same breed; average of repeated evaluations recommended where possible.
4. Orthopedic Foundation for Animals. "Preliminary Evaluations." ofa.org — read 8 September 2026: preliminary radiographs accepted from 4 months, read by the OFA staff veterinary radiologist and not sent to the outside consulting radiologists; quotes the 1997 reliability figures.
5. Orthopedic Foundation for Animals. "Hip Screening Procedures." ofa.org — read 8 September 2026: three randomly selected board-certified radiologists from a pool of 20 to 25 for dogs 24 months or older; chemical restraint not required but recommended.
6. Orthopedic Foundation for Animals. "Our Fees." ofa.org — read 8 September 2026: hip dysplasia over 24 months $45; hips and elbows together $50; hip preliminaries 4 to under 24 months $35.
7. Antech Diagnostics. "PennHIP." antechdiagnostics.com — read 8 September 2026: accurate in dogs as young as 16 weeks; turnaround generally 72 hours; veterinarian locator.
8. Powers MY, Karbe GT, Gregor TP, McKelvie P, Culp WT, Fordyce HH, Smith GK. "Evaluation of the relationship between Orthopedic Foundation for Animals' hip joint scores and PennHIP distraction index values in dogs." Journal of the American Veterinary Medical Association. 2010;237(5):532-541. doi:10.2460/javma.237.5.532 — 439 dogs of at least 24 months; 52% of OFA Excellent, 82% of Good, 94% of Fair and 80% of all OFA-normal dogs had a distraction index of 0.30 or higher.
9. Antech Diagnostics. "Measuring Hip Joint Laxity with PennHIP." antechdiagnostics.com — read 8 September 2026: distraction index is a unitless number from 0 to 1; a cut-off of approximately 0.30 below which hips have very low susceptibility to osteoarthritis.
10. Corley EA, Keller GG, Lattimer JC, Ellersieck MR. "Reliability of early radiographic evaluations for canine hip dysplasia obtained from the standard ventrodorsal radiographic projection." Journal of the American Veterinary Medical Association. 1997;211(9):1142-1146. PubMed 9364228 — 2,332 dogs of four breeds; reliability of preliminary normal grades 100% (Excellent), 97.9% (Good), 76.9% (Fair); of dysplastic grades 84.4% (Mild), 97.4% (Moderate); by age 89.6%, 93.8%, 95.2%.
11. Smith GK, Gregor TP, Rhodes WH, Biery DN. "Coxofemoral joint laxity from distraction radiography and its contemporaneous and prospective correlation with laxity, subjective score, and evidence of degenerative joint disease from conventional hip-extended radiography in dogs." American Journal of Veterinary Research. 1993;54(7):1021-1042. doi:10.2460/ajvr.1993.54.07.1021 — 142 dogs radiographed at 4, 6, 12, 24 and 36 months.
12. Santana A, Alves-Pimenta S, Franco-Gonçalo P, et al. "Early hip laxity screening and later canine hip dysplasia development." Veterinary World. 2022;15(3):679-684. doi:10.14202/vetworld.2022.679-684 — distraction index at a mean 6.6 months against the adult Norberg angle, r = −0.66.
13. Smith GK, Popovitch CA, Gregor TP, Shofer FS. "Evaluation of risk factors for degenerative joint disease associated with hip dysplasia in dogs." Journal of the American Veterinary Medical Association. 1995;206(5):642-647. PubMed 7744684 — 151 dogs of 13 breeds; distraction index a significant risk factor at 4, 12 and 24 months; Norberg angle not significant in either analysis.
14. Patricelli AJ, Dueland RT, Adams WM, Fialkowski JP, Linn KA, Nordheim EV. "Juvenile pubic symphysiodesis in dysplastic puppies at 15 and 20 weeks of age." Veterinary Surgery. 2002;31(5):435-444. doi:10.1053/jvet.2002.34766
15. Orthopedic Foundation for Animals. Hip dysplasia statistics by breed, disease-statistics database. ofa.org — retrieved 27 August 2026 via the breed filter; the database renders from a query interface and cannot be re-verified in one fetch.
16. Engdahl K, Malm Persson S, Andersson L, Ringmark S, Bjørnvad CR, Hedhammar Å, Höglund K. "Prevalence of hip and elbow dysplasia in young adult dogs in Sweden." Veterinary Record. 2026;198(12):e560-e573. doi:10.1002/vetr.70224 — 12,335 German Shepherds screened 2007 to 2016, 25.6% graded C to E.
17. Smith GK, Mayhew PD, Kapatkin AS, McKelvie PJ, Shofer FS, Gregor TP. "Evaluation of risk factors for degenerative joint disease associated with hip dysplasia in German Shepherd Dogs, Golden Retrievers, Labrador Retrievers, and Rottweilers." Journal of the American Veterinary Medical Association. 2001;219(12):1719-1724. doi:10.2460/javma.2001.219.1719 — 15,742 dogs from the PennHIP database 1983 to 2000; risk ratios per 0.1 of distraction index, breed thresholds, mean indices, the 4.95-fold German Shepherd probability, and sex dropped as non-significant, all from the full text, read 8 September 2026 from the copy hosted by the Institute of Canine Biology at icbblog.org.
18. Popovitch CA, Smith GK, Gregor TP, Shofer FS. "Comparison of susceptibility for hip dysplasia between Rottweilers and German shepherd dogs." Journal of the American Veterinary Medical Association. 1995;206(5):648-650. PubMed 7744685 — 74 Rottweilers compared with German Shepherds; German Shepherds at significantly greater risk of joint disease.
19. Spot Pet Insurance sample policy, form PET-P-20000-1024, underwritten by Independence American Insurance Company. spotpet.com — read 27 August 2026.
20. Kealy RD, Olsson SE, Monti KL, Lawler DF, Biery DN, Helms RW, Lust G, Smith GK. "Effects of limited food consumption on the incidence of hip dysplasia in growing dogs." Journal of the American Veterinary Medical Association. 1992;201(6):857-863. doi:10.2460/javma.1992.201.06.857 — 48 Labradors; 7 of 24 restricted and 16 of 24 free-fed dogs dysplastic by the OFA method at two years.
21. Smith GK, Paster ER, Powers MY, Lawler DF, Biery DN, Shofer FS, McKelvie PJ, Kealy RD. "Lifelong diet restriction and radiographic evidence of osteoarthritis of the hip joint in dogs." Journal of the American Veterinary Medical Association. 2006;229(5):690-693. doi:10.2460/javma.229.5.690 — median age at first radiographic hip osteoarthritis 6 years control-fed against 12 years restricted-fed.
22. Coe JB, Rankovic A, Edwards TR, Parr JM. "Dog owner's accuracy measuring different volumes of dry dog food using three different measuring devices." Veterinary Record. 2019;185(19):599. doi:10.1136/vr.105319 — 100 owners; individual accuracy from −47.83% to +152.17%.
23. Embrace Pet Insurance Help Center. "What Is the Waiting Period for Orthopedic Conditions?" embracepetinsurance.com — read 27 August 2026: 180-day orthopedic waiting period.
24. Healthy Paws / Westchester Fire Insurance Company. Pet Health Insurance Policy, filed form LD-50812 (07/18). healthypawspetinsurance.com — read 27 August 2026: 12-month hip dysplasia waiting period.

This article is educational and does not replace veterinary advice. Which screening to run, when, and whether a juvenile surgery is appropriate are decisions to make with your own vet and, where surgery is on the table, a board-certified surgeon with your dog's films on the screen.