When Do Great Danes Stop Growing? A Vet's Honest Timeline

By Jessica Ennis, DVM, CVA

Breed care · August 21, 2026 · 5 min read

Great Danes hit full height near 18 months, but bone density and joint maturity keep changing until closer to age two.

Owners bring me this question with a specific worry hiding underneath it: is my dog’s growth normal, or should I be doing something differently right now. The honest answer is that “when do Great Danes stop growing” has two different answers depending on whether you mean height or skeletal maturity, and conflating the two is where a lot of well-meaning owners get into trouble.

Height is largely finished by around 18 months. Skeletal maturity — the growth plates actually closing and bone density evening out — runs later, and giant breeds sit at the far end of that curve.

The premise owners walk in with

Most people expect a Great Dane to “stop growing” the way a Labrador does, just bigger. That’s not quite how it works. A Great Dane puppy can look nearly full height at ten or eleven months and still be, functionally, an immature dog. I’ve had owners tell me their dog “stopped growing” at a year because the tape measure at the shoulder wasn’t moving anymore, then be surprised when their vet flags open growth plates on X-rays taken for an unrelated limp months later.

The growth plates in large and giant breeds can stay open considerably longer than in small dogs — commonly into the 18 to 24 month range, sometimes later in the biggest individuals. Height stalls first because the long bones lengthen early in the process; density, cartilage-to-bone conversion, and joint conformation are still catching up. So the dog you’re looking at on their first birthday is tall, but not necessarily finished.

What’s actually still developing after “full height”

Three things keep changing after a Great Dane looks grown:

• Bone density and mineralization, which continue to firm up as the growth plates close.
• Muscle mass, particularly through the chest and hindquarters, which several sources describe filling in through age two to three, especially in males.
• Joint conformation, meaning how the hip and elbow surfaces settle into their final relationship — this is the piece most tied to lifelong mobility.

I’ve watched this play out with a Dane named Otis, a blue male who came in at 14 months, 130 pounds, owned by a couple who’d had him since he was eight weeks old. He looked like a finished adult — tall, deep-chested, moving well on flat ground. What the owners had noticed, almost as an afterthought, was that he tired faster on their Sunday hikes than he had at ten months, and he’d started sitting instead of standing during long waits at the vet’s front desk. Nothing dramatic. On exam his hips had a touch more laxity than I’d expect from a dog with his gait, and his growth plates weren’t fully closed yet on radiographs. Nothing alarming, but it changed how we talked about his exercise plan — less repetitive stair work, no organized running yet, more controlled leash walking on grass instead of pavement until he was closer to two.

Why the growth-plate window matters for joints, not just height

This is the part I think gets skipped in a lot of “growth chart” articles: the reason the timeline matters isn’t trivia, it’s that developmental orthopedic disease in large-breed dogs is directly tied to how fast and how heavily they grow during this window. Rapid growth paired with excess calcium or excess calories can disturb normal bone formation, contributing to conditions like osteochondrosis and hip dysplasia, according to a review of developmental orthopedic disease in large-breed puppies published in dvm360. That’s the practical reason large-breed puppy foods exist and why “just feed a bit extra to help him grow big and strong” is exactly backwards advice for a giant breed.

Diet matters here more than most owners expect going in. Today’s Veterinary Nurse notes that controlled growth — not maximized growth — is the goal for large and giant breed puppies, with calcium, phosphorus, and calorie density all managed more conservatively than a standard puppy formula would provide. A giant-breed puppy that grows too fast on too rich a diet is more likely to end up with the joint problems that shorten a mobile, comfortable adult life, not a taller adult dog.

Where the timeline actually lands, breed-specific

Pulling together growth-tracking data specific to the breed, Great Dane Care puts most Danes at their full height by around 12 to 18 months, with the vast majority done growing taller by 18 months at the latest, while weight and body mass can keep climbing into the second year. That tracks with what I see clinically: the frame is set well before the dog is “finished,” and everything after that is filling in, not lengthening.

If I’m counseling a new Great Dane owner, I tell them to plan around two years, not one, as the real finish line for skeletal maturity — even though the dog will look and act adult-sized well before that.

What I actually tell owners to do during this window

Keep exercise low-impact and controlled through at least 18 months. Leash walks on grass or dirt, short and frequent rather than long and occasional, and no organized running, jogging, or repetitive fetch on hard surfaces until growth plates have closed. Stairs and jumping on and off furniture are worth limiting too — not forbidding outright, just not encouraging.

Feed a large-breed-specific puppy formula, not a standard one, and don’t supplement calcium on your own. The calcium-to-phosphorus balance in a purpose-built large-breed diet exists specifically to slow growth to a rate the skeleton can keep up with.

Watch for the subtle stuff, not just limping. Sitting instead of standing at rest, hesitating before stairs, or tiring earlier on walks than they used to are often the first signs something’s uncomfortable — not a dramatic lameness.

Talk to your vet before neutering or spaying, and don’t rush it. Timing relative to growth-plate closure is a real conversation to have with your own veterinarian for a giant breed, not a one-size-fits-all default.

I’ve had this conversation enough times now that I’ve stopped assuming owners will read it in the growth chart on the puppy food bag. It’s worth saying out loud: your Great Dane’s frame is set early, but the joints that frame depends on are still finishing their work for months after that. Treat the first two years as a build phase, not a finish line, and the payoff is a dog whose joints have the best possible start.

If you’re weighing this Dane against a different breed for your household or thinking ahead to other mobility questions, our guides on the Border Collie vs Australian Shepherd comparison and best low-maintenance dog breeds for busy people cover how joint and exercise needs vary by breed. And if apartment living is part of the equation for a giant breed, our piece on best dog breeds for apartment living is worth a look before you commit.