What is Hip Dysplasia?

Hip dysplasia is a developmental orthopedic condition where the hip joint (a ball-and-socket joint) does not form properly. Instead of fitting snugly, the femoral head (ball) and acetabulum (socket) are loose and misaligned, causing abnormal wear, inflammation, and progressive joint degeneration. Over time, this leads to osteoarthritis, chronic pain, and reduced mobility.

Hip dysplasia is one of the most common orthopedic conditions in dogs, particularly in medium to large breeds. It also occurs in cats, most notably in Maine Coons.

Causes

Hip dysplasia is a polygenic condition, meaning multiple genes contribute to its development. Environmental factors also play a role:

  • Genetics: The primary factor; both parents contribute to the risk
  • Rapid growth: Puppies that grow too quickly (especially large breeds) are at higher risk
  • Overnutrition: High-calorie diets that promote rapid weight gain in puppies
  • Excessive exercise: High-impact activities during growth stages
  • Obesity: Excess weight accelerates joint deterioration

Commonly Affected Breeds

Dogs

  • German Shepherd
  • Labrador Retriever
  • Golden Retriever
  • Rottweiler
  • Great Dane
  • Saint Bernard
  • Bernese Mountain Dog
  • Bulldog
  • Newfoundland

Cats

  • Maine Coon (prevalence estimated at 18–24%)
  • Persian
  • Himalayan

Symptoms

Symptoms can appear as early as 4–6 months in puppies or develop gradually over years:

  • Reluctance to exercise, jump, or climb stairs
  • Bunny-hopping gait (both hind legs move together)
  • Stiffness, especially after rest
  • Difficulty rising from a lying position
  • Swaying or wobbly hindquarters
  • Clicking or popping sounds from the hip
  • Loss of muscle mass in the hind legs
  • Pain when the hip area is touched
  • Decreased range of motion

In cats, signs are often subtle: reluctance to jump, decreased activity, and irritability when handled.

Screening

OFA (Orthopedic Foundation for Animals)

The most widely used screening program in North America:

  • X-rays are taken under sedation at 2 years of age (or older)
  • Evaluated by three independent radiologists
  • Graded: Excellent, Good, Fair, Borderline, Mild, Moderate, or Severe
  • Only Excellent, Good, and Fair are considered "passing" for breeding

PennHIP

An alternative method:

  • Can be performed as early as 16 weeks
  • Measures joint laxity using a distraction index (DI)
  • Provides a breed-specific percentile ranking
  • Considered more objective and predictive than OFA evaluation

Why Screening Matters for Breeders

  • All breeding dogs of predisposed breeds should be screened
  • Only dogs with passing hip scores should be bred
  • Screening both parents significantly reduces the incidence of hip dysplasia in offspring
  • Reputable breed clubs and registries require hip clearances
  • Consistent screening over generations has dramatically improved hip scores in many breeds

Treatment

Conservative Management

  • Weight management (the single most important factor)
  • Controlled, low-impact exercise (swimming is ideal)
  • Physical therapy and rehabilitation
  • Joint supplements (glucosamine, chondroitin, omega-3 fatty acids)
  • Anti-inflammatory medications (NSAIDs)
  • Pain management

Surgical Options

For severe cases or young dogs:

  • Juvenile Pubic Symphysiodesis (JPS): Performed at 16–20 weeks; modifies pelvic growth
  • Triple Pelvic Osteotomy (TPO): Rotates the acetabulum for better coverage; for young dogs without arthritis
  • Femoral Head Ostectomy (FHO): Removes the femoral head; creates a "false joint"; suitable for smaller dogs and cats
  • Total Hip Replacement (THR): The gold standard for severe cases; replaces the joint with an artificial one
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