A puppy’s journey: from a single cell to a 12-week-old puppy

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See the incredible development of a puppy inside its mother’s womb, and the remarkable changes it undergoes in its first few weeks of life.

The gestation period for dogs is only around 9 weeks, but in that time the most incredible transformation occurs. And that’s before it even takes its first breath as a newborn puppy. Come and learn about the remarkable journey of a puppy, from its mother’s womb to the big wide world.

Puppy in the mother's womb.


Week 1-2: from cell to foetus

Woohoo! Today my egg is fertilised in the fallopian tube and I can start my big journey. Together with my future brothers and sisters, I leave for the womb. We distribute ourselves nicely, so that no one is alone, and nestle up tight in the soft uterine wall. I divide from 4 to 64 cells and immediately get a head and spine!

puppy's growth in the womb

Week 3-4: as big as a hazelnut!

At the 19th day, I hide even better within the uterine wall. Unfortunately, this can make mummy feel a bit sick, but it won’t last too long. In week four, my head grows, I get eyes and my first vertebrae. I am now growing very fast and I have almost tripled in size. Did you know that I am already about 15mm?

That's as big as a hazelnut! I also get my organs. If mummy’s owners want to see us for the first time, the vet can help them to do this with his ultrasound.

puppy's growth in the womb

Week 5-6: I’m a boy!

I look more and more like a real puppy, with teeth, toes, nails and whiskers. I can take good care of myself because my own organs are already completely finished. I get my skin colour. Mummy is finding it a bit difficult, because she has become much heavier and we are very busy down here in our little swimming pool. Most excitingly, we are now becoming a boy or a girl. And guess what? I’m a boy! I was lucky to get a good spot in the womb. Because I am in the middle, where the most food comes, I become the strongest in the group. After week six I weigh about 6 grams and I am 45mm.

Fully Growth of puppy in the womb

Week 7-9: Preparing for the outside world

Mummy’s owners can now see me very clearly with ultrasound, because my skeleton is already finished. They can also feel me when I try to give a little kick. Mummy is almost bald on her stomach, so that I can easily find where to drink from. The last few weeks are pretty hard for her, but I'm almost there! I put all my energy into growing, growing and growing some more. Eating becomes more difficult for her, because we take up so much space. A more concentrated diet can be a solution. From day 57 (beginning of week nine) I can safely come out, although I’ll usually wait until 60 to 63 days. I cannot wait to play!

New born puppy


Newborn to 2 weeks: Sleep and grow!

Well, hello world! Except, I can’t see anything yet. Or hear. We are all blind, deaf and toothless for the first week or two, and unable to regulate our own body temperature. My brothers, sisters and I depend on mummy and each other for warmth, and we huddle together in a big cosy pile.

It’s been a busy few weeks of growing, so I spend 90 percent of my time sleeping! All the energy I do have is used for growing, and my weight has already doubled in the first 10 days.

I can’t support my own weight yet but I can just about crawl about using my front legs.

Puppy outside the world

Week 2 to 4: I can see! And hear! And walk! And talk!

There have been lots of changes in my second week of life. My ears and eyes have both opened, giving me a whole new sense of the world around me. Mummy looks as lovely as I knew she would and so do all my little fluffy brothers and sisters. We are all starting to chat a bit more now with little yelps, whines, and barks. Oh, and very excitingly, by week three, I took my first wobbly walk!

This is a time of rapid physical and sensory development for us puppies, and we are starting to play with each other and even cheekily trying food from mummy’s bowl. I’m starting to control my toilet needs a bit better and moving away from where we sleep when I need to go.

fully developed puppy with children's

Week 4 to 12: Time to get social!

I’m told that week three to about week 10 is an important socialisation period and I will form attachments that I will remember the rest of my life!

Mummy’s milk started to slow down at around four weeks and now I’m eating lots more solid food. By the time I am six-week-old puppy, all my baby teeth are in, which really helps with eating.

At weeks six to eight, I am at a really important period to learn to accept others as a part of the family. By the time I am a ten-week-old puppy (and they say this happens from about week eight to 12), I find I am a little scared of meeting new people, and I appreciate it when my owners are very careful with socialisation during this period.

Staying with my brothers and sisters and my mummy at this stage is helping me to learn all sorts of useful things: bite inhibition, how to understand and react to normal canine communication, and my place in doggy society.

Now I am a twelve-week-old puppy, and I am ready to meet my owners and move into a cosy house of my own! How exciting!

You’ve got a new puppy, now what are you going to call it? Read our guide to naming a new dog.

Want to know more?

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Guide to insuring your dog

Four week's free pet insurance from Petplan

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Date of review December 2020

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