OFA vs. PennHIP: Which Hip Evaluation Method Is Better for Breeding Dogs?

Both methods evaluate hip health — but they measure different things, work at different ages, and serve breeding programs in different ways

If you are selecting a stud dog and looking at hip certifications, you will encounter two main systems: OFA (Orthopedic Foundation for Animals) and PennHIP (Pennsylvania Hip Improvement Program). Both are credible, both are informative, and both are accepted by responsible breeders. Understanding how they differ helps you evaluate results meaningfully.

OFA Hip Evaluation: How It Works

The OFA method evaluates the structural appearance of the hip joint from a single radiographic view taken with the dog in a specific extended-leg position. Three independent OFA-approved radiologists grade the film, and the consensus rating is reported.

Minimum age: 24 months for official certification (preliminary exams can be done at any age but are not certifiable)

What it measures: Conformational appearance of the hip joint — how well the femoral head fits into the acetabulum, presence of subluxation, and evidence of degenerative joint disease

Ratings: Excellent, Good, Fair (certifiable) | Borderline, Mild, Moderate, Severe dysplasia (not certifiable)

Cost: Approximately $35-$50 for the OFA reading (plus veterinary fees for the radiograph itself)

Strengths:

• Simple pass/fail result that is easy for buyers to understand
• Large historical database enabling breed-level comparisons
• Publicly searchable at ofa.org — results can be verified independently
• Accepted across virtually all breed clubs and registries
• Does not require specialized equipment beyond standard radiograph capability

Weaknesses:

• Can only be performed officially after 24 months of age
• The extended-leg position may not reveal hip laxity that is only apparent under distraction
• Does not provide a quantitative laxity measurement
• Interrater variability exists (three radiologists may not always agree)

PennHIP: How It Works

The PennHIP method measures hip joint laxity (looseness) using a distraction technique. The dog is anesthetized, and a distraction device is placed between the hind legs while radiographs are taken. This forces the femoral heads laterally, revealing how much laxity exists in the joint — laxity that the standard OFA extended-leg position often conceals.

Minimum age: 16 weeks (PennHIP can be performed on young puppies)

What it measures: Hip joint laxity, expressed as a Distraction Index (DI)

DI Score:

• Ranges from 0 (no laxity) to 1 (complete subluxation)
• A DI of 0.3 or lower is considered low risk for developing osteoarthritis
• A DI above 0.7 indicates significant laxity and high risk
• Results are compared against breed-specific norms — what is acceptable varies by breed

Cost: More expensive than OFA, typically $300-$500+ when including the required sedation and trained radiologist

Strengths:

• Can identify hip laxity much earlier (16 weeks vs 24 months)
• Quantitative measurement provides a more nuanced picture than pass/fail
• Research has shown PennHIP DI is a better predictor of future osteoarthritis than OFA rating
• Identifies dogs with significant laxity that may rate "Good" on OFA extended-leg view
• Allows earlier selection decisions in working dog programs

Weaknesses:

• Requires anesthesia (carries inherent risk, especially in young puppies)
• Requires training — veterinarians must be certified by PennHIP to perform the evaluation
• Not all areas have PennHIP-certified practitioners
• More expensive
• Database is not publicly searchable in the same way OFA is
• Less universally recognized by breed clubs outside working dog programs

Which Is Better?

The honest answer: they complement each other more than they compete.

PennHIP is better at:

• Early prediction of future hip disease
• Quantifying laxity that OFA may miss
• Providing breed-normed comparisons
• Informing breeding decisions before dogs reach 24 months

OFA is better at:

• Universal recognition across breed clubs and registries
• Easy, publicly verifiable results at ofa.org
• Lower cost and more accessible practitioners
• A consistent, intuitive rating system for buyers

Research Comparison

Multiple independent studies have examined whether OFA and PennHIP agree with each other. The findings are sobering for OFA proponents: a meaningful percentage of dogs that receive OFA ratings of Good or Excellent have DI scores on PennHIP that indicate elevated laxity and future osteoarthritis risk. This does not mean OFA is worthless — it means PennHIP catches some dogs that OFA clears.

However, OFA databases are much larger and have longer historical records, making breed-level trend analysis more comprehensive.

What to Expect From Stud Dog Owners

Both OFA and PennHIP results are legitimate. For a stud dog, you should accept either:

• OFA rating of Excellent, Good, or Fair (with preference for Good or better)
• PennHIP Distraction Index below the breed median (ideally well below)

Ask for the actual OFA number (verifiable at ofa.org) or the PennHIP report from a certified practitioner. Verbal assurances are not sufficient. Photographs of reports should be verified when possible.

Summary

OFA evaluates hip joint conformation from a single extended-leg view at 24+ months, providing an Excellent-to-Severe rating that is publicly verifiable. PennHIP measures joint laxity using a distraction technique at any age from 16 weeks, producing a quantitative DI score compared to breed norms. PennHIP is a better predictor of future osteoarthritis; OFA is more universally recognized and accessible. For breeding decisions, both are credible — know how to read each result and verify documentation directly.