What is a good PennHIP score for an American Bulldog?

Lower is better. The American Bulldog breed median Distraction Index is 0.50, so a score under 0.50 is tighter than half the breed. Under 0.30 is considered a tight hip with low arthritis risk. ABRA counts a PennHIP DI under 0.50 as qualifying hips for the Blue Ribbon Brood Stock designation.

At what age can a dog get PennHIP tested?

PennHIP can be performed from 16 weeks of age because it measures joint laxity rather than waiting for arthritis to appear. One result is valid for life. OFA, by contrast, requires the dog to be at least 24 months old for a permanent rating.

Why does PennHIP require sedation?

The test measures how loose the hip is when muscles are fully relaxed. That can only be measured under heavy sedation or general anesthesia, because a conscious dog tenses its muscles and hides the true laxity.

Do I need both OFA and PennHIP for ABRA?

No. For the Blue Ribbon Brood Stock designation a dog qualifies on hips with either OFA Fair or better, or a PennHIP Distraction Index under 0.50. You also need the dog clear of ICH and NCL to earn BRBS.

How do I find a vet who can do PennHIP?

Use the official PennHIP veterinarian locator on the Antech Imaging Services website. Only trained, certified members are authorized to perform and submit PennHIP studies. Call ahead to confirm the certification is current, that they take all three required views, and that they submit the films for an official report.

PennHIP Testing for American Bulldog Breeders: What It Is, Why It Matters, and How to Find a Certified Vet

By Lesli Rose · Owner of the American Bulldog Registry & Archives and the Olde Bulldogge Breed Association · American Bulldog breeder since 1998 · Updated June 16, 2026

Across 28,904+ American Bulldogs from 6 registries indexed since 1998.

If you breed American Bulldogs and you only ever run one health test on your dogs, make it a hip test. Hips are the single biggest structural problem in the breed, and they are also the one problem you can actually measure before you breed. PennHIP is the most predictive hip test available, and on the ABRA registry a good PennHIP score is now one of the ways a dog earns the Blue Ribbon Brood Stock designation that prints on its certificate.

This guide explains what PennHIP measures, why it is worth the cost, and exactly how to find a vet who is certified to perform it.

Hip dysplasia is not a rare problem in this breed. Of 2,495 American Bulldogs evaluated by the Orthopedic Foundation for Animals (OFA), only 60.9 percent scored normal hips and 34.8 percent were dysplastic (OFA breed statistics). Those are the odds you are breeding against when you do not test.

What PennHIP actually measures

PennHIP stands for the University of Pennsylvania Hip Improvement Program. It is now administered by Antech Imaging Services. Unlike a standard hip X-ray, PennHIP measures passive hip laxity, which is how loose the hip joint is when the muscles are fully relaxed. Joint laxity is the single best early predictor of whether a dog will develop hip dysplasia and arthritis later in life.

The result is a number called the Distraction Index, or DI. It runs from roughly 0 to just over 1. Lower is better, because lower means a tighter joint:

Under 0.30 is considered a tight hip. Dogs in this range are unlikely to develop hip arthritis.
The low 0.40s is a genuinely nice hip for the breed.
Around 1.0 is a very loose joint with high arthritis risk.

The DI is most useful when you compare it to the breed. PennHIP and Antech publish a breed laxity table, and for the American Bulldog the current breed median Distraction Index is 0.50 (range 0.13 to 1.31, mean 0.51, as of the table updated March 2026). A dog under 0.50 is tighter than half the American Bulldogs ever tested. That is the bar ABRA uses.

PennHIP vs OFA: do you need both?

OFA (the Orthopedic Foundation for Animals) is the other common hip evaluation. OFA rates a single hip-extended X-ray as Excellent, Good, Fair, Borderline, or one of three dysplastic grades, and it can be done from 24 months of age. PennHIP can be done as early as 16 weeks because it measures laxity rather than waiting for arthritis to show up.

For the ABRA Blue Ribbon Brood Stock designation, you do not need both. A dog qualifies on hips if it is either:

OFA Fair or better (Fair, Good, or Excellent), or
PennHIP below the breed median, meaning a Distraction Index under 0.50.

Many serious breeders run PennHIP because it gives them a real number to select on and lets them test young dogs before they invest two years into them.

What is in it for the breeder

Health testing is not a cost. It is an asset you pay for once and sell from for years. Here is the honest case for spending the money:

You test the parents once, and it sells every puppy you ever breed from them. The designations that come from testing ride on every puppy's certificate and pedigree for the life of your kennel.
It unlocks the marks that print on the ABRA certificate. Hips that qualify, plus clear ICH and clear NCL, make a dog Blue Ribbon Brood Stock. Breed two BRBS dogs together and the litter is a Blue Ribbon litter. Those are ownable marketing assets that untested litters simply do not have.
It justifies your pricing. Tested, titled, BRBS stock separates your litter from a backyard litter at the exact moment a buyer is deciding. The certificate is your proof, in hand, at the table.
It protects your program. Knowing hip laxity before you pair dogs means fewer dysplastic puppies, fewer heartbroken buyers, fewer refunds, and fewer rumors about your line. Testing is far cheaper than one returned dog.
It compounds your kennel's value. Under ABRA your breeder prefix stays with the dog forever. Documented health down a pedigree raises the worth of the entire bloodline, not just one dog.

How to find a PennHIP-certified vet, step by step

Not every veterinarian can perform PennHIP. The vet has to complete PennHIP training and stay certified, and the three-view radiographs have to be taken a specific way. Here is how to find the right one.

Step 1: Use the official PennHIP vet locator

Go to the Antech PennHIP website and use their "Find a PennHIP Member" or veterinarian locator tool. Search by your city, state or province, or postal code. Only vets listed there are trained and authorized to submit PennHIP studies.

Step 2: Call and confirm three things

Phone the clinic before you book and confirm:

They are currently PennHIP certified (certifications can lapse).
They take the full three views PennHIP requires: the distraction view, the compression view, and the standard hip-extended view.
They will submit the films to PennHIP so you get an official Distraction Index and breed percentile report, not just an in-house opinion.

Step 3: Plan for sedation

PennHIP requires the dog to be heavily sedated or under general anesthesia. The muscles must be completely relaxed to measure true joint laxity, and that cannot be faked on an awake dog. Ask the clinic about their sedation protocol, fasting instructions, and any pre-anesthetic bloodwork they want first.

Step 4: Pick your timing

PennHIP can be done from 16 weeks of age, which is its big advantage for breeders making early keep-or-place decisions. If you are testing a dog specifically for breeding, many breeders test once the dog is grown so the result reflects the mature animal. Either way, one PennHIP result is valid for life because laxity does not improve with age.

Step 5: Ask about cost and the report

PennHIP costs more than a basic X-ray because of the sedation, the extra views, and the submission fee. Ask for the all-in price up front. When the report comes back, you will get the DI for each hip and where your dog falls against the breed. Keep that report.

Step 6: Record it so it counts

Add the result to your dog's profile on the American Bulldog Archive, and send it to ABRA. Once it is on file, a qualifying hip score (together with clear ICH and NCL) earns the Blue Ribbon Brood Stock mark, and that mark prints on the dog's ABRA registration certificate and travels with every puppy you breed from it.

How ABRA uses your hip results

ABRA reads your recorded health tests when it generates a registration certificate. A dog is marked Blue Ribbon Brood Stock when it has qualifying hips (OFA Fair or better, or PennHIP DI under the 0.50 American Bulldog median) and is clear of both ICH (Ichthyosis) and NCL (Neuronal Ceroid Lipofuscinosis). When both the sire and the dam of a litter are Blue Ribbon Brood Stock, that litter is a Blue Ribbon litter, and every puppy carries the distinction on its paperwork.

That is the whole point of testing. You do the work once on the parents, and ABRA turns it into a permanent, verifiable mark on every dog that comes after them.