Hip dysplasia in dogs starts with a hip joint that doesn’t form correctly during growth, creating looseness (laxity) between the ball of the thigh bone and the socket of the pelvis. This laxity allows the joint to shift and grind in ways it shouldn’t, gradually wearing down cartilage and reshaping the bone itself. It’s one of the most common inherited orthopedic conditions in dogs, but genetics alone don’t tell the whole story. A combination of inherited predisposition and environmental factors during a puppy’s development determines whether the condition takes hold and how severe it becomes.
What Happens Inside the Joint
A healthy hip is a ball-and-socket joint. The round head of the femur (thigh bone) fits snugly into a cup-shaped socket in the pelvis. In a dog with hip dysplasia, the socket is too shallow, the ball is misshapen, or the surrounding ligaments and soft tissue are too loose to hold everything in place. The result is a joint that slides around more than it should.
That excess movement is the root of everything that follows. Each time the dog walks, runs, or jumps, the femoral head partially slips out of the socket and then back in. This repeated micro-shifting is called subluxation, and it creates abnormal pressure on the cartilage lining both surfaces of the joint. Over time, that cartilage erodes. The body tries to stabilize the joint by laying down new bone around the edges, but this bony remodeling only makes the fit worse and leads to osteoarthritis, a painful, progressive inflammation of the joint.
This progression from laxity to cartilage loss to arthritis can unfold over months in a fast-growing puppy or over years in a mildly affected dog. Some dogs show signs before they’re a year old. Others don’t develop noticeable problems until middle age, when the cumulative joint damage finally catches up.
The Genetic Foundation
Hip dysplasia is a polygenic disorder, meaning it isn’t caused by a single gene but by many genes scattered across the genome, each contributing a small effect. This is why breeding out hip dysplasia has been so difficult despite decades of effort. Two parents with good hips can still carry enough of these small-effect gene variants to produce an affected puppy, and two mildly affected parents can occasionally produce a puppy with excellent hips.
Certain breeds carry a much higher genetic burden. According to the Orthopedic Foundation for Animals, about 20.4% of German Shepherds and 19.3% of Golden Retrievers evaluated have dysplastic hips. Large and giant breeds are most commonly affected, but medium-sized and even some smaller breeds can develop the condition. The genetic lottery determines whether a dog’s hip sockets form deep enough, whether the surrounding soft tissue provides adequate support, and how the bones grow relative to each other during the critical first year of life.
Environmental Triggers During Growth
A puppy can carry the genetic predisposition for hip dysplasia and never develop a clinically significant case, or it can develop a severe case that might have been milder under different conditions. Several environmental factors during the first months of life play a surprisingly large role.
Exercise and Surfaces
The type of physical activity a puppy gets matters more than most owners realize. Research has found that puppies who walked on stairs from birth to three months of age had an increased risk of developing hip dysplasia. In contrast, puppies who got off-leash exercise on soft, moderately rough ground during that same window had a decreased risk. The likely explanation is that stairs force repetitive, high-impact loading on developing joints, while free movement on natural terrain allows puppies to self-regulate their activity and build supporting muscle without excessive joint stress.
Puppies born on farms and those born in spring or summer (when more outdoor time on soft ground is available) also showed lower rates. Slippery indoor floors, like hardwood or tile, can contribute to the problem as well, since puppies splay their legs to stay upright and repeatedly stress the hip joint in unnatural positions.
Growth Rate and Nutrition
Puppies that gain weight rapidly are more likely to develop hip dysplasia, and the condition tends to appear earlier and become more severe in fast-growing dogs. The mechanism is straightforward: bone and muscle grow at different rates, and excess body weight puts mechanical stress on joints before the surrounding structures are mature enough to handle it.
Overfeeding is the main culprit. High-calorie diets that push a large-breed puppy to grow as fast as possible create exactly the conditions where a genetically predisposed hip joint is most likely to fail. This is why large-breed puppy foods are formulated with controlled calorie density and carefully balanced mineral ratios. The goal isn’t to restrict growth permanently but to slow the pace so bones, cartilage, and soft tissue develop in sync.
Early Spaying or Neutering
Reproductive hormones influence how long bones continue to grow and when growth plates close. A large study from UC Davis found that mixed-breed dogs weighing more than 44 pounds as adults face a significantly higher risk of joint disorders, including hip dysplasia, if neutered before one year of age. In female dogs over 43 pounds, the risk of joint problems jumped from about 4% in intact dogs to 10-12% in those spayed before a year old. The hormonal changes from early neutering appear to alter the timing of bone growth, potentially creating the kind of structural mismatch that leads to joint laxity. For large and giant breeds, many veterinarians now recommend waiting until at least 12 months of age.
Signs That Develop Over Time
Hip dysplasia doesn’t always announce itself with dramatic symptoms. In young dogs, the earliest signs are often subtle: a reluctance to climb stairs or jump into the car, stiffness after resting, or a characteristic “bunny hopping” gait where both back legs move together instead of alternating. Some puppies seem to tire easily during walks or sit with their legs splayed to one side rather than tucked neatly underneath.
As the condition progresses and arthritis sets in, you may notice your dog having more difficulty getting up from a lying position, losing muscle mass in the thighs, or showing obvious discomfort when the hips are extended. The hind end can develop a swaying, loose-looking walk. Pain levels often fluctuate. A dog might seem fine after a warm-up walk but stiffen dramatically after a long rest, especially in cold weather. Because the progression from laxity to full-blown arthritis can take years, many owners initially attribute the early signs to normal puppy awkwardness or aging.
How Hip Dysplasia Is Detected
Veterinarians use a combination of physical examination and imaging to diagnose hip dysplasia. During a hands-on exam, a vet can check for the Ortolani sign, a specific “clunk” felt when the loosened femoral head is manually pushed out of and back into the socket. This test directly measures joint laxity.
Two main radiographic methods are used for formal evaluation. The OFA (Orthopedic Foundation for Animals) method takes a standard X-ray of both hips in an extended position and grades them from Excellent to Severe. This is typically done at two years of age when the skeleton is mature. The PennHIP method can be performed earlier and uses a specialized technique to measure exactly how far the femoral head can be pushed out of the socket, expressed as a distraction index from 0 (perfectly tight) to 1 (fully dislocated). Dogs with a distraction index above 0.4 are considered at increased risk.
For breeders, these screening tools are essential for making informed decisions about which dogs to pair. For pet owners, early detection opens the door to interventions like weight management, controlled exercise, and joint-supportive therapies that can slow the progression toward arthritis and keep a dog comfortable for years longer than it might be otherwise.