Dogs go through different developmental stages in their lives. Being aware of these can help (potential) dog owners to better understand and support the development of their four-legged friends.  

  • Prenatal phase: duration of pregnancy (approx. 60-63 days)
  • Neonatal stage: 1st & 2nd week of life
  • Transitional phase: 3rd week of life
  • Socialization phase: 4th - 12th (or 14th) week of life
  • Juvenile phase: 12th (or 14th) week of life - sexual maturity 
  • The Onset of puberty: male approx. 5 - 7 months of age; female approx. 7 - 11 months of age. 
  • Maturity phase (1.5 - 3 years of age)
  • Ageing: starts approx. from the 7th year of life

Each of these phases is characterized by physical, hormonal and behavioural changes and fundamentally prepares the dog for the following stages in his life. Already in the first eight weeks, puppies show about 80% of the entire behavioural repertoire of an adult dog. The duration of each phase can vary depending on the individual dog and its breed.  


Prenatal phase 

In the mother’s womb, mainly the hereditary dispositions are determined. The future behaviour of the young animals is thus already shaped before birth. Research has shown that female dogs who were growing between two males in the mother’s uterus later showed a more masculine appearance as well as male courtship behaviour (Sachser and Kaiser 1996). The reason for this is an increased testosterone level, which is passed on to the unborn via the placenta. Hormones, therefore, play an important role in the development of the embryos during pregnancy. It is all the more important that the mother is in a safe and calm environment, as particular stress hormones can have a considerable impact on the unborn puppies. Puppies of highly stressed mothers are often born lighter, smaller, and more nervous. Other possible factors influencing the young animals in the mother’s womb are nutrition, (either sufficient or a lack thereof) exercise, and the administration of medication. Nevertheless, the development of behaviour is not exclusively determined by hereditary factors. Environmental factors like experiences are just as important. "Behaviour is 100% innate and 100% learned." (Nikolaas Tinbergen). The genetic make-up of the puppy is primarily an offer to the environment. However, behavioural patterns develop later depending on environmental influences. That's where the breeders come in first and dog owners later. 


Neonatal phase  


"He, who grows up only in paradise, can survive only in paradise." (Barbara Schönig) 

The puppies are born blind and deaf and spend most of their time sleeping or resting. Excretion of faeces and urine is stimulated mainly by the mother's licking. The puppies can perceive touch, smell, taste, and pain as well as warm and cold temperatures. They are already exposed to initial stress at this time, which can be triggered by hunger, cold, or pain. They use vocalisation to draw attention to themselves. The mother almost always responds to this kind of cry for help, but only during the first 12 days of life. Characteristic of this phase is the puppies' slow crawling movements while searching for something, which enables them to find the mother’s milk. Their motor skills develop from the front legs to the back legs. Puppies must go through this process without external help, as mild stress is essential for the proper development of their organism. Breeders should therefore not simply place puppies against the mother's belly but rather give them the chance to do this on their own. Mild stress favours and promotes the development of the puppies' immune system, motor skills, thermoregulation and adaptability.   


Transitional phase 

As the transition phase begins, the puppies' eyes and ears slowly open and milk teeth begin to erupt. Towards the end of the 3rd week of life, puppies manage their first controlled movements and can poo and urinate on their own. This is the optimal time to get the puppy adapted to different surfaces. Learning to be house-trained is made much easier, for example by setting up crates with a natural surface. At the end of this phase, the puppies can process visual and auditory stimuli and consciously perceive their environment for the first time, such as their mother and siblings. Everything that can be reached is deliberately checked by smelling, licking, or nibbling. In addition, the puppies show pronounced vocalisation during stress, for example when they are alone in an unknown place.  


Socialisation phase 

This phase forms the basis for the dog's future behaviour. The puppy's brain is fully independent here. The nerve cells that have been laid down are effectively linked together, based on what the puppy has experienced. Connections that haven’t been used are being undone. The more different environmental influences a puppy gets to experience, the more connections are made in the brain. And the more connections are made, the easier it is for them to learn and the better they can adapt to their environment. Nevertheless, it is important not to flood a puppy with new influences, otherwise, they will not be able to rest. Phases where the puppy feels active should be used to your advantage, but moments of rest are important.  

During this phase, socialisation and repetition are one of the most important things. Through socialisation, the puppy becomes used to its living environment and learns how to deal with it.  Dogs are social creatures. This means that contact with other living creatures and those from their own species is vital for them. Nevertheless, it’s important to know which living beings are included in this. In addition to people and other dogs, it’s necessary to introduce them to other pets which belong to the family or who are living in the same house, such as cats, rabbits, horses, etc… there is a lot to be learned when in contact with other dogs. Although social gestures are innate, a puppy must first learn how to recognise and correctly filter them. To do this, dogs of different breeds and ages should be introduced to them from early on. Same with people, it is an advantage to meet different ages and sexes. Through habituation, the puppy gets used to its non-living environment such as different surfaces, traffic, vehicles or other objects. The puppy builds some kind of reference system through the quality and quantity of the environmental influences experienced during this time, which is valid for a lifetime. In the brain, all these experiences are stored and classified as normal or harmless. New stimuli can thus be classified in the reference range or compared with it. It may form a poor reference system if there is a lack of corresponding environmental experiences. Such dogs often react with fear to everyday things. Dogs then experience damage due to deprivation, which can be irreversible. It is therefore important to familiarise a puppy with the stimuli it will encounter in everyday life.  

Puppies are often particularly curious and active up to the 8th week of their life. Between the 3rd and 5th week of life, puppies are largely free of fear due to physiological processes and exploratory behaviour that is predominant. However, from the 8th week of life, there is a shift and fearful behaviour can come to the surface. This is usually the time when a puppy moves in with us. As (potential) dog owners, we should be aware of this problem and allow the puppy plenty of time and peace to settle in. We also shouldn’t leave him/her alone during this time, as it must get used to its new home first. It is up to us to prepare the puppy as best as possible for its life. It is important to establish rules here because these give the puppy orientation and security. In any case, we can playfully teach what is allowed and what is not and thus already create the basis for a harmonious life. Nevertheless, long rest periods are necessary in order to process and memorise what has been learned. 


Juvenile phase 

The juvenile phase is often referred to as the adolescence phase. Socializing and getting used to the living and non-living environment should be continued during this time. Social skills must be practiced and consolidated so that the dog is not lost later. Young dogs try to find their place in the family more and more and like to question previously established rules and boundaries. They do not do this to annoy us, but rather to find out where they belong and whom they can trust. Consistent but kind parenting is, in my opinion, essential. Studies at the University of Bristol have shown that dogs strive to form quality relationships with confident peers. So, if we set appropriate boundaries for our young dog, we are at the same time giving him a place of safety, orientation, and security. In this process, tone and inner attitude play the music. People who shout or get angry primarily show insecurity. Our dog can only trust us if we set appropriate boundaries and always remain calm and reliable. Everyone gets angry sometimes, that's clear. But if we are aware from the beginning of what our dog needs in this orientation phase, we are already on our path to success.  

Physiological processes also take place during the adolescence phase. From the 4th month, puppies begin to teeth. To prevent them from destroying our furniture, I can offer my young dog an alternative to chewing. The change of teeth is often paired with pain or discomfort and chewing can help with this, much like it does with human babies.  In addition, the young dog's skeleton (cartilaginous primordial skeleton) is being remodelled into a permanent, bony skeleton through complex histological transformation. However, skeletal growth is not fully completed until 16 - 18 months of age.  


The onset of puberty 

Puberty is a great challenge for many dog owners. Our wannabe adult dogs want to push limits and frequently react stubbornly or even somewhat rude. In males, puberty begins with the urine marking behaviour, i.e., lifting the leg. In females, it begins with the first heat. This is often accompanied by a "sensitive phase". From about 8-month, young dogs often go through another anxious phase, which is actually a total disaster for us. Things that were previously taken for granted suddenly seem scary and previously learned behaviour suddenly seems completely forgotten. But who can blame them? Just think back to puberty. The hormones go crazy and the brain once again overturns all previously established connections. This is where our leadership skills come into play. We should never be discouraged if our dog suddenly questions or ignores our rules and opinions. We should simply stay on the ball and approach the matter with a lot of patience and loving consistency. Previously learned behaviours are by no means forgotten forever, just pushed into the back corner for a moment.  


Maturity stage 

Even if the young dog appears quite grown-up, physical and mental maturity is not yet complete. So, in this phase our dogs mature step by step into adulthood.  



After the seventh year of life, the first signs of ageing start to appear in a dog. However, this varies from individual to individual, especially due to the great diversity of breeds. It is important to understand that dogs always remain capable of learning. But with age, the ability to learn slows down. Of course, physical, mental complaints or limitations can occur with increasing age. Nevertheless, go ahead and do all the things with your dog that give you pleasure and quality of life, regardless of age! 


In summary, 

puppies learn continuously and quickly until they are adults. The transitions between the individual phases are fluid. It is important to get to know your puppy first, just as it gets to know us humans. Based on this, you can think about how to approach those individual stages of development with him. What does my puppy need? Is he more curious or shy? Can I slow him down in his exploratory urge or does he need the necessary push to enter new situations?  As always in life, it's all about balance. Overload can be a potential danger, but so can overprotection. Try to show your puppy your world and introduce him to the environment at your own pace. As Goethe so beautifully said, "Children should get two things from their parents: roots and wings."  

Why shouldn’t our dogs get that too?