Five years ago, my dachshund Hatsu gave birth to six puppies in a whelping box I had built in our living room in Madrid. I sat on the floor next to her for most of the first forty-eight hours, half from anxiety, half from sheer fascination. One of those puppies, Luna, still sleeps three feet away from where I’m writing this. The other five went to families I helped choose, and I stayed in touch with all of them.
What follows is what actually happens as a puppy develops, week by week, from the perspective of someone who watched it happen six times at once. I’ll tell you what the books say, what veterinary research backs up, and where my own experience differed from the textbook timeline. There’s a lot of generic content about puppy development on the internet. I want this to be the one you remember.
Quick answer
A puppy’s development falls into four main stages: neonatal (weeks 0–2), transitional (weeks 2–4), socialization (weeks 3–12), and juvenile (months 3–6). Eyes open around days 10–14, first wobbly steps come in week three, weaning begins in week four, and a puppy is ready for a new home at eight weeks minimum. Different breeds develop at slightly different speeds, but the order of milestones is remarkably consistent across all dogs.
A quick-reference timeline
If you want the whole thing at a glance before reading the detail, here it is:
| Week | What’s happening |
|---|---|
| 1 | Eyes and ears closed. Sleeping, nursing, doubling birth weight. |
| 2 | Eyes start to open. First tiny sounds. |
| 3 | First wobbly walking. First teeth. Hearing develops fully. |
| 4 | Real personalities show. Mom starts weaning. First play. |
| 5 | Solid food increasing. Bite inhibition lessons from siblings. |
| 6 | Fully weaned. First vaccines. First deworming. |
| 7 | Critical socialization with humans intensifies. |
| 8 | Ready to leave mom. First fear period begins. |
| 9–12 | Settling into new home. Vaccinations continue. Heavy learning. |
| 13–16 | Socialization window closing. Vaccinations complete. |
Week 1: the neonatal stage
A newborn puppy is essentially a small, warm, blind, deaf mammal that can do exactly three things: find a nipple, suckle, and sleep. That’s not a criticism. It’s a survival design that has worked for thousands of years. Their eyes are sealed shut, their ear canals are closed, and their nervous system isn’t developed enough for them to control their own body temperature. They are completely dependent on their mother for warmth, food, and even basic elimination, since Hatsu had to lick the puppies’ bellies to stimulate them to pee and defecate.
What surprised me most that first week was how much they grew. By day seven, all six puppies had doubled their birth weight. You can almost see it happening. They go from looking like wet, wrinkly hamsters to looking like proper puppy versions of themselves, just very small ones. They squeak when they’re cold, they go silent when they’re warm, and the whole pile moves as one organism when Hatsu leaves them.
A healthy newborn puppy should gain roughly 5 to 10 percent of their body weight every day during this first stretch. If you’re raising a litter and a puppy isn’t gaining, that’s the most important thing to catch early. The runt of Hatsu’s litter took an extra day or two to find her stride, but she caught up. The other clue I learned to watch for: a healthy newborn is quiet most of the time. Crying that goes on and on isn’t normal puppy behaviour. It’s a signal.
Week 2: the world starts to come into focus
This is when things start happening. Around day ten or twelve, you’ll notice a little slit of dark colour where the eyelid has been smooth for a week. Over the next two or three days, the eyes open properly. The first sight a puppy has is blurry and grey, and their vision won’t be fully developed for another month or two, but the change is enormous. Suddenly they have a sense of where their mother is rather than just navigating by smell and warmth.
Hearing develops around the same time. In Hatsu’s litter, I noticed the first reactions to sound around day fourteen. I had been playing music quietly in the room from day one, on the advice of a breeder I trust, who told me that puppies raised in totally silent rooms tend to be skittish about household noise later. By the end of the second week, the puppies would twitch when I dropped something.
They’re still sleeping most of the day, still feeding constantly, and still gaining weight steadily, but they’re no longer just passive lumps. You can see them notice each other for the first time. They start to crawl with purpose rather than just dragging themselves toward warmth.
Week 3: walking, teeth, and the beginning of personality
Week three is when a puppy starts to look like a puppy. By around day twenty, most are taking their first wobbly steps. They fall a lot, they walk sideways, they bump into things, but they’re moving. Their tails start to wag, usually clumsily at first. Their hearing is now fully developed, and they react to voices, footsteps, and other dogs.
The first teeth come through during this week. In dachshunds, like most breeds, the canines and front incisors come first. These are needle-sharp baby teeth, and Hatsu started looking less enthusiastic about nursing the moment they appeared. That’s not coincidence. The discomfort of being bitten while nursing is a natural mechanism that begins the weaning process.
This is also the week when temperature regulation kicks in properly. The puppies no longer need their mother as a heat source. They can leave the pile to explore, then come back. This sounds small, but it’s actually the first time they exist as individuals rather than as part of a single warm organism.
Week 4: real puppies emerge
By the time a puppy is four weeks old, they look and behave like a tiny adult dog. They walk confidently. They run, in a wobbly way. They play with their siblings, and that play has structure: pounces, play-bows, mock-fights, brief naps, repeat. This is when the first real personalities appear, and they’re more distinct than you might expect.
In Hatsu’s litter, by week four I could already tell which puppy was bold and which was cautious. The one who would later become Luna pushed her way to the front of the food bowl every time. One of her brothers hung back and let the others eat first. These early patterns turned out to be remarkably persistent. Luna is still the one who walks into a new room first. Her brother, now living in Valencia, is still the one who watches from the doorway.
This is also when weaning begins in earnest. Hatsu started spending more time away from the puppies. She’d lie in the next room, or on the sofa, and the puppies would notice and complain, and then they’d settle. She’d come back to nurse, but for shorter and shorter periods. Around this time I introduced a shallow bowl of mushy puppy food softened with a bit of warm water and goat’s milk. The first time, mostly they walked through it. By the third try, they were eating.
Barking starts now too, though it’s more of a hoarse little woof than a proper bark. It’s funny to listen to. A bark from a four-week-old dachshund is the most absurd sound on Earth.
Week 5: weaning and bite inhibition
By week five, the puppies are eating solid food several times a day, supplemented by less and less milk. Hatsu’s nursing visits got shorter, and she started doing something that I had read about but hadn’t seen in person: she would correct the puppies. Not aggressively, but firmly. If a puppy bit her too hard, she’d give a low growl and turn away. If they were too rough, she’d stand up and leave the box. The puppies learned, fast, that there are consequences for biting too hard.
This is one of the most underrated parts of puppy development. The lessons a puppy learns about bite inhibition from their mother and siblings during weeks four through eight are extremely difficult to replicate later. It’s a major reason why responsible breeders insist on keeping puppies until eight weeks minimum. A puppy that leaves at six weeks misses these lessons, and that puppy almost always grows up with a worse sense of how hard is too hard. I’ve watched it happen with people who took puppies too young from other litters.
The puppies also start to explore beyond the whelping box. Mine couldn’t yet jump out, but they could climb to the edge and survey the territory. They started using a designated corner for elimination instead of going wherever they were, which is the first sign of an instinct that you’ll later use for potty training.
Week 6: solid food, first vaccines, first humans
At six weeks, the puppies in my litter were fully weaned. Hatsu still let them nurse occasionally, but it was less about milk and more about comfort. Their primary food source was now mush and increasingly less mushy puppy food.
This is when the first round of vaccines and the first deworming happen. I worked with my vet on the exact schedule, which varies slightly by country and by breed, but generally the first shots cover distemper, parvovirus, and parainfluenza, and the first deworming addresses common parasites. The vet also did a basic check on each puppy: heart, lungs, palate, hips, eyes, ears, and the general look of them. All six checked out healthy, which is not always the case in a litter.
This is also when I started having visitors. Carefully. Not strangers off the street, but people I trusted, who washed their hands, took their shoes off, and sat quietly while the puppies decided whether to approach. Not every puppy approached every visitor. That’s important data. The bold ones came up immediately. The cautious ones watched from a distance and then decided, on their own, when to come closer. I never forced an interaction, and I never let a visitor pick up a puppy who hadn’t chosen to come over.
If you’re getting a puppy from a breeder, this is the week and the next one where you should be asking what kind of socialization the breeder is doing. A good breeder will tell you in detail. A bad breeder will say “they meet plenty of people” and not be able to elaborate.
Week 7: the critical socialization window opens wide
If there’s one week in a puppy’s development that matters more than any other for the rest of their life, it’s somewhere between weeks seven and twelve. The biology of this window is fascinating: a puppy’s brain produces higher levels of certain neurotransmitters that make them naturally curious and accepting of new experiences. After about week fourteen, they become more cautious by default. Anything they didn’t get to experience positively before the window closes will be harder to introduce later.
This is the period where puppies should be meeting many different kinds of people. Tall people, short people, children, elderly people, people with beards, people wearing hats, people in wheelchairs, people with different skin tones, people walking with canes. They should be hearing different sounds at low, gradually increasing volumes: vacuum cleaners, washing machines, thunder recordings, traffic, fireworks. They should be walking on different surfaces: tile, wood, carpet, grass, sand, metal grates. They should be touched in all the ways they’ll be touched later in life: paws handled, ears looked into, mouth opened gently, tail lifted.
This sounds like a lot, and it is. The breeder Pat Hastings popularised what she calls the 100/100/100 regimen: 100 people, 100 dogs, 100 different experiences, all before the puppy turns four months old. It’s an ambitious target, but the principle behind it is sound. The more variety a puppy experiences during this window, the more resilient and confident they’ll be as an adult.
There’s a real tension here that you need to know about. The critical socialization window opens before vaccinations are complete, which doesn’t finish until around week sixteen. The temptation is to keep the puppy at home until they’re fully vaccinated. The problem with that is the window will already be closing by then. The American Veterinary Society of Animal Behavior put out an official statement on this years ago, and the position is clear: the behavioural risks of inadequate socialization outweigh the disease risks, provided you socialize thoughtfully. That means controlled environments, vaccinated and known dogs, not dog parks. It means carrying the puppy in public if you’re nervous. It means puppy classes after the first round of shots (with a one-week wait for immunity).
I’ll go into much more detail on how to do this safely in the socializing your puppy guide. For now, the key point is that the work has to start in week seven, with the breeder doing the initial heavy lifting and the new owner taking over the moment the puppy comes home.
Week 8: the day they leave
Eight weeks is the standard age at which a puppy goes to a new home, and there are good reasons for it. By week eight, a puppy is physically independent: weaned, mobile, drinking water, eliminating on their own. They’ve had their first vaccines and their first lessons in bite inhibition from their siblings. They’re ready, biologically, to bond with new humans.
But there’s a catch. Weeks eight through ten coincide with what’s called the first fear period. During this time, anything traumatic that happens to a puppy can leave a lifelong imprint. A bad car ride. A frightening encounter with another dog. A loud noise at close range. This isn’t theoretical. Studies on canine behavioural development consistently show that puppies traumatised during the first fear period are more likely to develop adult anxieties and phobias.
This is why I always tell families picking up a puppy: the first week is not about training, not about discipline, not about meeting everyone you know. It’s about a calm, gentle, positive introduction to their new life. Visitors stay away. Loud noises are managed. Car rides are short. The puppy goes from a known environment to a new one, and everything they experience in that transition should be neutral or positive.
When Hatsu’s six puppies left, they went to six different homes between days 56 and 60. I drove some of them myself. The handover I’ll always remember was the puppy who later got named Bruno, going to a family in Madrid. They lived a thirty-minute drive away, and I’d told the family to make the car ride as calm as possible. They put a t-shirt that smelled like their own home in the carrier with him. He slept the whole way. They sent me a photo that night of him asleep on a bed they’d made up for him near their own.
Five years later, Bruno still sleeps in that same spot, his family tells me.
What happens after week 8
Once a puppy goes to a new home, the standard development continues but the responsibility shifts. Weeks nine through twelve are heavy learning weeks: the puppy is settling in, starting potty training, meeting more of the world, getting more vaccines. The critical socialization window is still wide open through week twelve and starting to narrow through week sixteen.
Around week sixteen, vaccinations are typically complete and the puppy can safely visit anywhere, including dog parks (though I’d argue dog parks are a bad idea before six months for entirely different reasons). The first set of adult teeth begins to come in around month four or five, replacing the baby teeth, and you’ll find tiny teeth around the house for weeks.
The juvenile stage, roughly weeks twelve through twenty-four, is when adolescence starts. The puppy is no longer a baby. They’re a teenager. They will test boundaries, ignore commands they previously followed, and forget basic training overnight. This is normal. It does not mean your puppy is broken. It means they have a brain that’s developing.
By the end of the first year, a small breed like a dachshund is mostly adult-sized. Larger breeds like Labradors and Goldens keep growing through eighteen months. Giant breeds keep developing past their second birthday. Mental maturity lags behind physical maturity in every breed. Most dogs aren’t really mentally adult until somewhere around age two.
How development varies by breed size
The order of milestones is consistent across all breeds. The timing isn’t quite. Small breeds like dachshunds, Yorkshires, and miniature poodles tend to walk slightly later than the textbook timeline suggests, sometimes by a day or two. Giant breeds like Great Danes or Mastiffs grow much more slowly proportionally and stay puppy-mentally for longer. A two-year-old Great Dane is still a teenager. A two-year-old dachshund is a fully formed adult.
In Hatsu’s litter, all six puppies hit the standard milestones within a day or two of each other. The bigger puppies in the litter walked first by a day. The smallest, my Luna, was always a day behind on physical milestones but caught up by week six and overtook the others in personality development. She was the first to bark, the first to play, and the first to climb out of the whelping box.
Warning signs: when to call the vet
Most puppies develop on schedule without intervention. When something is wrong, it usually shows in the first three weeks, and it shows clearly. A puppy who isn’t gaining weight, who feels cold to the touch even with their mother nearby, who refuses to nurse, or who cries continuously for long stretches is telling you something. Puppies who haven’t opened their eyes by day sixteen need to be seen. Puppies who can’t stand by week three need to be seen. Puppies who are visibly smaller than their littermates and not catching up need to be seen.
The earlier you catch a problem, the better the outcome. Puppy mortality is real and it usually happens in the first two weeks. Don’t wait to see if things improve. With newborn puppies, hours matter.
What I’d tell my younger self
If I could go back to the first weekend of Hatsu’s whelping, the only thing I’d change is being calmer. The puppies were fine. Hatsu knew what she was doing. The biology had been refined over thousands of years to work without my supervision. My job was to provide a safe, warm, quiet environment and to call the vet if something looked wrong. That was it.
The thing I got right, almost by accident, was starting socialization early. Not formal socialization, but the small handling and exposure that happens when a breeder is in the room with the puppies every day from week one. Studies on early neurological stimulation back this up: puppies who are gently handled from birth are more confident, more resilient, and easier to train as adults. The five minutes a day I spent picking up each puppy, looking them over, putting them down again, probably mattered more than I realised at the time.
If you’re raising a litter, do that. If you’re choosing a breeder, ask them whether they do that. The answer tells you everything you need to know about the kind of dog you’re about to bring home.
Where to read next
If you’ve just read this and you’re about to bring a puppy home, I’d point you to the bringing a puppy home checklist for the practical setup, and to the socializing your puppy guide for the most important work of the first months. If you’re choosing a breed and considering a dachshund, my complete wire-haired dachshund guide has ten years of personal experience with the breed and what to expect.
