Puppy Development From Newborn to One Week Old

Puppy development from a puppy at one week to four weeks and then onto the four to six month and older puppy stage of their lives can be a long and very confusing time for both pet parents and puppy owners. At the one week and four weeks stages the puppy is physically and mentally so different from what it will be as a one year old, that there is no way to communicate or even get together what is to come in terms of the future.

However, at one week, a puppy’s brain is at least a third of it’s full size. It is the size of a new born baby’s brain, so there is a large amount of growth and change occurring.

At this stage, the puppy’s brain is just being developed and is forming new nerve connections, making them able to process information.

The developing puppy brain is in constant communication with the outside world, and in order to form this communication it must rely on senses that are also being developed, so the developing puppy is able to interpret, understand and react to the world around them.


A newborn puppy’s senses are just developing and the puppy is not being able to interact with the world around it. Their senses are only able to form in response to stimuli they are experiencing.

A newborn puppy is completely dependent on their mother for life, but this is not the case for a puppy that is being cared for in a home.

The puppy is also very vulnerable, because of their lack of senses, and their body being completely new, their skin is in a delicate state. To protect themselves from the elements, a newborn puppy has its hair, the puppy’s first line of protection, developed, however the puppy does not yet have a waterproof coat like an adult.

A newborn puppy also has a developing bladder and digestive system. The puppy is experiencing its first bowel movement and is only able to digest about 1/3 of what a puppy of one year eats. A mother will eat the first bowel movement to help with digestion, as well as drinking her puppies urine.

The digestive system does not yet have a fully developed gastrointestinal tract, which is why this stage is known as “the milk stool”. A puppy drinks mothers milk during this time and they are unable to digest food. A puppies stomach acid has not yet been developed.

At birth, a puppy has an average body temperature of 96 degrees Fahrenheit and is constantly sucking to stimulate the release of milk from the mother’s mammary glands. The sucking reflex will also help with their first bowel movement as well as stimulate blood flow through the heart.

One Week

At a puppy’s one week, the puppy is beginning to physically develop and is starting to look like a young adult, however their internal development has barely begun. It is the first time the puppy has really separated itself from its mother, and started on its own, and is very dependent on the mother’s love, but this is also a time when the puppy will be at its most vulnerable. At this stage, they are experiencing hunger, and the puppy’s new eyes can only see in black and white, the first thing the puppy will do when it is hungry is find the mother’s nipple, and begin to suckle.

At this stage of development, the puppy is not being able to control its body. It still has not developed it’s limbs and it is beginning to control the tail, the puppy can only move on all fours or it will not develop properly.

Puppy’s limbs are not yet developed, the puppy only has four tiny limbs in the front of the puppy’s body and is tail in the back, but both are underdeveloped. The puppy’s brain is also very tiny and their brain has only begun to grow, the puppy’s brain only weighs a quarter of the weight of a full grown puppy.

At this stage, the puppy is still very vulnerable and should not be pet or handled too much because it could harm or confuse the puppy. It is also important to remember that their eyesight is not fully developed, so direct stimulating light should be avoided.