Hip Dysplasia in Dogs (HD): Grades, Diagnosis, Treatment
Hip dysplasia in dogs (HD): grades, diagnosis, treatment
What is hip dysplasia in dogs?
Hip dysplasia (HD, Canine Hip Dysplasia) is a developmental malformation of the hip joint (articulatio coxofemoralis): the femoral head and acetabulum do not fit together optimally — the joint socket is too shallow (acetabular dysplasia), the femoral head is insufficiently congruent, or the joint is too lax (increased joint capsule laxity). The result is abnormal joint loading, progressive osteoarthritis, and pain.
HD is one of the most common orthopedic conditions in dogs — caused multifactorially by genetics, nutrition, growth rate, and body weight.
Background + scientific classification
Lust (1997, Journal of the AVMA, https://pubmed.ncbi.nlm.nih.gov/9154207/) describes the pathogenesis of hip dysplasia: HD develops from a mismatch between joint laxity and periarticular muscle stabilization during the growth phase. In dogs with a genetic predisposition, the acetabulum develops too shallow — the femoral head subluxates under load. Chronic microtrauma leads to synovitis, joint capsule inflammation, fibrosis, and gradual osteoarthritis. Heritability is estimated at 0.3–0.5 — polygenic inheritance influenced by environmental factors. Not breeding HD-positive dogs is the most important preventive measure.
Smith et al. (2006, JAVMA, https://pubmed.ncbi.nlm.nih.gov/16131612/) demonstrate the influence of nutrition on HD progression in a long-term study: In a controlled study with Labrador Retrievers, dogs with restricted calorie intake (25% less than ad libitum) showed significantly fewer radiographic signs of hip osteoarthritis over the course of their lives. Normal body weight during the growth phase reduces mechanical joint loading and considerably slows HD progression. Excess weight is the strongest modifiable risk factor — even in genetically predisposed dogs.
Ettinger et al. (2017, Textbook of Veterinary Internal Medicine) describe diagnostic and treatment options: HD is diagnosed radiographically using standardized positioning (ventrodorsal pelvic view with the hind limbs extended, under sedation). FCI grading scale: A (normal) → B (near normal) → C (mild HD) → D (moderate HD) → E (severe HD). Treatment: conservative (weight control, NSAIDs, physiotherapy, hydrotherapy, acupuncture as an adjunct); surgical: TPO (Triple Pelvic Osteotomy, < 8 months), DARthroplasty, FHO (femoral head and neck ostectomy), THA (total hip replacement = gold standard for severe HD).
Vitomalia position
HD is not a diagnosis you can ignore — pain is real and progressive. The good news: excess weight is the most modifiable risk factor. If you raise a predisposed puppy optimally (no excess weight, no overloading, HD-screened parent animals), you significantly reduce the risk.
When does HD become relevant?
- Large breeds: routine HD examination before breeding
- Puppies of predisposed breeds: careful rearing (no excess weight, no overexercise)
- Lameness, stiffness, reduced weight-bearing in the hindquarters: suspected HD → X-ray
- Bunny hopping (both hind legs moving together when running): a classic sign of HD
- After an HD diagnosis: regular follow-up checks, long-term weight management
Practical application
FCI HD assessment scale:
| Grade | Designation | Radiographic finding |
|---|---|---|
| A | Normal | Optimal congruence of femoral head/acetabulum |
| B | Near normal | Minimal incongruence, no pathological finding |
| C | Mild HD | Mild incongruence, early signs of osteoarthritis |
| D | Moderate HD | Clear incongruence, subluxation, signs of osteoarthritis |
| E | Severe HD | Marked subluxation/luxation, severe osteoarthritis |
Treatment options by severity and age: - HD C in a young dog (< 8 months): consider TPO (triple pelvic osteotomy improves acetabular roof coverage) - HD C/D in an adult dog, conservative: NSAID, weight management, physiotherapy, hydrotherapy, joint support (omega-3, glucosamine as a supplement) - HD D/E: FHO (femoral head ostectomy) or THA (total hip replacement) — indication based on degree of suffering
Common mistakes & myths
- “HD always means pain and lameness.” The HD grade does not necessarily correlate with pain intensity — some dogs with E-grade HD compensate well, while some dogs with C-grade HD show severe pain. Clinical assessment is more important than radiographic grading alone.
- “Puppies from parents with HD will definitely get HD.” HD is polygenic and influenced by environmental factors. HD-positive parents increase the risk, but they do not guarantee it. Conversely, A/B parents can also produce offspring with HD.
- “Swimming or cycling is harmful for HD.” Joint-friendly exercise (swimming, hydrotherapy) is explicitly recommended for HD — building muscle around the hip joint stabilizes the femoral head. Intensive impact loads (climbing stairs, jumping) should be reduced.
Scientific status 2026
HD X-ray screening is established in breeding — Germany (SV breeding survey, KHZG HD evaluation), Austria (ÖKV), and the FCI have binding breeding requirements. PennHIP (distraction index) is gaining importance as an alternative measurement method for earlier diagnosis (from 16 weeks). Genetic markers for HD are being identified — its polygenic architecture currently makes single-gene tests of limited practical use. THA outcomes in dogs are excellent, with a > 90% success rate.
Frequently asked questions
What does HD grade mean in dogs?
The HD grade (A to E according to FCI) describes the extent of hip joint malformation on the X-ray: A = normal, B = near normal, C = mild, D = moderate, and E = severe hip dysplasia. Dogs with grades C, D, and E are excluded from breeding in most clubs.
Which dog breeds are particularly affected by HD?
Particularly affected: German Shepherd, Labrador Retriever, Golden Retriever, Rottweiler, Saint Bernard, Mastiff, Newfoundland. In general, large and heavy breeds have a significantly higher risk of HD than small breeds.
Can HD in dogs be treated?
Yes — conservatively with weight management, NSAIDs, physiotherapy, and hydrotherapy, or surgically (TPO in young dogs, FHO or total hip replacement in adult dogs). The choice of treatment depends on the dog’s age, severity, and level of suffering.
Related terms
Sources & further reading
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Lust, G. (1997). An overview of the pathogenesis of canine hip dysplasia. Journal of the American Veterinary Medical Association, 210(10), 1443–1445. https://pubmed.ncbi.nlm.nih.gov/9154207/
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Smith, G. K., Paster, E. R., Powers, M. Y., Lawler, D. F., Biery, D. N., Shofer, F. S., et al. (2006). Lifelong diet restriction and radiographic evidence of osteoarthritis of the hip joint in dogs. Journal of the American Veterinary Medical Association, 229(5), 690–693. https://pubmed.ncbi.nlm.nih.gov/16131612/
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Ettinger, S. J., Feldman, E. C., & Côté, E. (Eds.) (2017). Textbook of Veterinary Internal Medicine (8th ed.). Saunders. ISBN 9780323312110.