What Is Hip Dysplasia in Dogs, and What Actually Causes It

By David Hirsch, DVM, CVA, CVCH, MS-TCVM

✓ Medically reviewed by David Hirsch, DVM, CVA, CVCH, MS-TCVM — August 28, 2026 For general education — not a substitute for veterinary care.

Joint supplements · August 30, 2026 · 6 min read

Hip dysplasia starts as loose joint fit, not pain — and by the time a dog limps, the joint has usually been remodeling itself for months.

A ten-week-old Golden Retriever puppy trots across an exam room floor, tail up, hips swinging a little wide. Nothing about that gait is abnormal to look at. But if I put my hands on that pup’s hips and gently extend and abduct them, I can sometimes feel the femoral head shift a few millimeters more than it should — a soft, subtle give. That give is the whole story of hip dysplasia in one motion. It isn’t a disease that arrives; it’s a joint that never quite locked into the shape it was supposed to hold.

What’s actually loose in the joint

The hip is a ball-and-socket joint: the femoral head is the ball, the acetabulum is the socket. In a well-formed hip, that ball sits deep and snug, held there by the joint capsule, the round ligament, and the surrounding musculature. Canine hip dysplasia is what happens when the socket is shallow, the ligaments are lax, or both — so the femoral head rides loose instead of centered. Coxofemoral laxity is the hallmark of hip dysplasia in young dogs, according to the American College of Veterinary Surgeons. That laxity is the mechanical root of everything downstream: uneven wear on the cartilage, bone remodeling at the socket rim, and eventually osteoarthritis.

I braid the musculoskeletal picture with whole-patient balance whenever I evaluate a dysplastic hip, because the joint doesn’t fail in isolation — the muscling around it, the dog’s weight, and its gait pattern all shift the load that unstable joint has to absorb.

Where the instability comes from

The Merck Veterinary Manual describes the pathophysiology plainly: a disparity between hip joint muscle mass and rapid bone development creates the laxity, which then triggers acetabular sclerosis, osteophyte formation, and joint capsule fibrosis as the body tries to stabilize a joint that was never built tight in the first place. Genetics sets the baseline. According to Cornell University Riney Canine Health Center: Cornell University’s Riney Canine Health Center, hip dysplasia is polygenic and heritable, which is why breed-level screening programs exist and why prevalence varies so widely from one breed to the next.

But genetics isn’t the whole causal chain, and this is where I part ways with owners who treat hip dysplasia as purely a breeding-lottery outcome. Growth rate and nutrition during the puppy months can magnify or blunt that genetic predisposition. A large-breed puppy fed free-choice, growing fast and heavy before its supporting muscle and ligament tissue catches up, puts more mechanical stress on an already-loose joint than a littermate raised on a measured, controlled-calcium diet. Excess calcium supplementation in growing puppies has been specifically flagged as a risk multiplier, not a protective step — more calcium does not mean stronger hips.

A case that changed how I explain this to owners

I once worked up a nine-month-old Labrador who’d been “bunny hopping” on stairs for two months before the owner brought it up — she’d assumed it was puppy clumsiness. On palpation, both hips showed a positive Ortolani sign, that distinct clunk of subluxation and reduction. Radiographs confirmed moderate dysplasia bilaterally. The owner’s first question wasn’t about treatment; it was whether she’d caused this by overfeeding a large-breed puppy formula past the recommended amount. I told her the honest answer: genetics almost certainly set the stage, but the growth curve likely determined how early and how visibly it showed up. That distinction — predisposition versus trigger — is the one conversation I have most often in this exam room.

How the joint changes as the dog ages

In puppies, the presentation is laxity — a loose, sometimes wobbly hip that hasn’t yet developed secondary arthritis. Owners may notice a bunny-hop gait, reluctance to jump, or exercise intolerance that looks like normal puppy fatigue. As dogs mature into young adulthood, the joint capsule and surrounding tissue often thicken in response to the chronic instability, which can paradoxically make some dogs more comfortable for a stretch even as osteoarthritis quietly builds. By middle age and beyond, that remodeling — bone spurs, a thickened femoral neck, cartilage loss — is what produces the stiffness, reduced range of motion, and muscle atrophy in the hindquarters that owners of older large-breed dogs recognize.

Where I’ve seen this go wrong

A failed approach I see often: owners wait for a limp before asking about hips, because laxity alone doesn’t hurt. By the time a limp shows up, the joint has frequently been undergoing degenerative change for months. I’d rather a large- or giant-breed puppy get an OFA or PennHIP evaluation around the time of spay or neuter than wait for a visible gait change. It’s not alarmist — it’s just earlier information, and earlier information changes what’s actually feasible: weight management, controlled exercise, and joint-support strategies land differently in a six-month-old than in a five-year-old with established arthritis.

An edge case worth knowing

Not every loose hip becomes a painful one. I’ve examined dogs with moderate radiographic dysplasia who never showed a clinical sign in their life, and dogs with mild radiographic changes who were profoundly lame. Body condition, muscle mass, and activity level appear to explain a meaningful part of that gap — a lean, well-muscled dog can functionally compensate for a joint that looks worse on film than it behaves in the exam room. That’s not a reason to skip screening. It’s a reason not to treat a radiograph as a verdict on a dog’s quality of life.

What actually helps, in structure-and-function terms

I don’t talk about curing hip dysplasia, because there’s no undoing a shallow socket. What’s realistic is supporting the joint tissue that’s already under load. Glucosamine and chondroitin are among the most studied joint support ingredients for dogs, per Boops Pets’ vet-reviewed claim list. In vitro work suggests glucosamine HCl may help prevent experimentally induced cartilage degradation, per a review indexed at Journal of Veterinary Medical Science: 10.1292/jvms.25-0293, and chondroitin has been associated with supporting healthy synovial fluid homeostasis in research published at Frontiers in Veterinary Science: 10.3389/fvets.2026.1536366. Green-lipped mussel extracts, studied in a rodent model, alleviated paw swelling and reduced markers of inflammation including TNF-α and IL-17, according to research at Nutrients: 10.3390/nu18020215 — worth noting as mechanistic evidence, not a promise of outcome in dogs. None of this replaces weight control, controlled exercise, or a veterinary orthopedic exam; it sits alongside those things.

If you’re weighing what belongs in a joint supplement scoop for a dysplastic dog, our companion piece on what actually belongs in the scoop walks through label-reading in more depth, and our breakdown of avocado soy unsaponifiables versus glucosamine is useful if you’re comparing ingredient classes rather than brands. For dogs already showing hip symptoms, I’d also point owners toward our piece on whether swimming actually helps a dysplastic hip before assuming any exercise is safe exercise.

Where this leaves an owner

Hip dysplasia is a structural story before it’s a pain story. The joint’s fit is set early — largely by genetics, meaningfully modified by growth rate and nutrition — and the arthritis that follows is the body’s long response to that instability, not a separate disease. The dogs I worry about least aren’t the ones with a diagnosis on file; they’re the ones whose owners know the diagnosis exists and plan the next several years around it.