Hip dysplasia in dogs is caused by a combination of genetics and environmental factors that disrupt normal hip joint development during puppyhood. It’s a polygenic condition, meaning multiple genes contribute to it, and things like diet, growth rate, exercise, and even the timing of spaying or neutering can determine whether a genetically predisposed dog actually develops the problem.
How the Hip Joint Goes Wrong
A healthy canine hip is a ball-and-socket joint where the top of the thighbone (the femoral head) fits snugly into a cup-shaped socket in the pelvis. In hip dysplasia, the core issue is a mismatch between how fast a puppy’s bones grow and how quickly the surrounding muscles develop to support those bones. When muscle mass can’t keep up with skeletal growth, the joint becomes loose and unstable.
That looseness, called joint laxity, is where the damage begins. A loose-fitting ball slides partially out of the socket with normal movement, a process called subluxation. Because cartilage in young dogs is softer and more pliable than bone, the repeated abnormal pressure from a poorly seated femoral head gradually deforms the socket rim. Over time, the body responds with bone spurs, thickening of the joint capsule, and scarring, all hallmarks of osteoarthritis. The condition is progressive: mild laxity in a four-month-old puppy can become painful arthritis by middle age.
Genetics Are the Biggest Factor
Hip dysplasia is heritable, and breeding history matters enormously. When both parents have dysplastic hips, roughly 85% of their offspring will develop the condition. If only one parent is affected, about 52% of puppies will be dysplastic. Even when both parents have normal hips, 37.5% of offspring can still develop it, because the genes involved are numerous and can be carried silently across generations.
This polygenic nature makes hip dysplasia difficult to breed out of a population. There’s no single gene to test for. Instead, breeders rely on radiographic screening: OFA evaluations, which provide official certification after age two, and PennHIP testing, which measures joint laxity and can be performed as early as 16 weeks. Dogs with hip dysplasia, or with a family history of it, should not be bred.
Breeds Most at Risk
While any dog can develop hip dysplasia, certain breeds are dramatically more susceptible. According to the Orthopedic Foundation for Animals database, the breeds with the highest dysplasia rates include:
- Olde English Bulldogge: 73.5% dysplastic
- Pug: 72.5%
- Bulldog: 70.9%
- Brussels Griffon: 57.7%
- Dogue de Bordeaux: 57.3%
- St. Bernard: 49.8%
- Neapolitan Mastiff: 49.5%
Large and giant breeds dominate the list, but smaller breeds like Pugs and Brussels Griffons show that body size alone doesn’t explain the risk. Structural conformation plays a role too. Breeds with wide, heavy bodies and relatively shallow hip sockets are predisposed regardless of their overall size.
Overfeeding and Rapid Growth
Nutrition is the most significant environmental trigger. Puppies that eat too many calories grow faster than their skeletal system can handle, and that excess weight puts abnormal stress on joints that aren’t fully formed yet. In a well-known long-term study, Labrador Retrievers fed freely (as much as they wanted) developed significantly more severe hip dysplasia than a matched group kept on restricted portions. The overfed dogs also had markedly worse osteoarthritis in their hips and elbows as adults, along with measurable differences in growth-related hormones.
The mechanism is straightforward. A puppy’s joint cartilage hasn’t yet hardened into bone through a process called endochondral ossification. When a heavy puppy loads that soft cartilage before it’s ready, the socket deforms. The combination of subluxation and excess body weight essentially reshapes the acetabular rim, turning mild genetic laxity into a structural problem. Keeping large-breed puppies lean during their first year is one of the most effective things an owner can do to reduce risk.
Calcium and Mineral Imbalances
It’s not just calories that matter. The mineral content of a puppy’s diet, particularly calcium, plays a direct role in skeletal development. Large-breed puppies need dietary calcium in the range of 0.8% to 1.2% on a dry matter basis, with a calcium-to-phosphorus ratio between 1.1:1 and 2:1. Too much calcium can be just as harmful as too little, because excess calcium disrupts the hormonal feedback loop that regulates bone growth.
This is why veterinary nutritionists specifically recommend large-breed puppy formulas rather than all-purpose puppy foods. Standard puppy diets are often too calorie-dense and too high in calcium for breeds prone to skeletal problems. Supplementing calcium on top of a commercial diet is particularly risky and generally unnecessary.
Exercise in Growing Puppies
The type of physical activity a puppy gets during the first year also affects joint development. Repetitive high-impact exercise, like intense ball-chasing with a launcher, jogging alongside a bike, or forced leash running on hard surfaces, puts concussive stress on immature joints. This kind of jarring, repetitive loading can worsen existing joint laxity and accelerate cartilage damage before the skeleton has reached maturity.
That doesn’t mean puppies should be kept sedentary. Free play on varied terrain actually supports coordination, balance, and healthy muscle development around the joints. The key distinction is between self-directed play, where the puppy can stop when tired and move in varied directions, and forced repetitive exercise that doesn’t allow for rest. Short, varied play sessions on grass or soft ground are far better than long marches on pavement or obsessive fetch sessions.
Early Spaying and Neutering
The timing of sterilization has emerged as another contributing factor. Sex hormones play a role in signaling growth plates to close as a dog approaches maturity. When a dog is neutered well before those growth plates have closed, the long bones can grow slightly longer than they would have otherwise. That extra length may be enough to alter joint alignment and increase the risk of a clinically apparent joint disorder.
A large study across 35 breeds found that the impact varies significantly by breed, sex, and size. For breeds already prone to hip dysplasia, neutering before skeletal maturity (which occurs later in large breeds, often around 12 to 18 months) can meaningfully increase risk. This doesn’t mean sterilization should be avoided entirely, but the timing is worth discussing with your vet, especially for large and giant breed dogs.
Why It’s Always Multiple Causes at Once
Hip dysplasia is rarely the result of one single factor. A genetically predisposed puppy that’s kept lean, fed an appropriate large-breed diet, allowed to exercise naturally, and neutered after skeletal maturity may never show clinical signs. The same puppy overfed and pushed through intense exercise could develop painful arthritis by age three. Genetics load the gun, but environment pulls the trigger. The practical takeaway: you can’t change your dog’s genes, but you have real control over the factors that determine whether those genes cause problems.