Dog's pregnancy progress

On the day of mating, the sperm, which are viable in the female reproductive tract for around a week, migrate upwards through the cervix and the uterine cavity.

The sperm only reach their full fertilisation capacity after the 5 to 8 hour journey through the uterus.

Then the exciting development of the fertilised eggs into small puppies begins.

The eggs fertilised in the fallopian tube ampoule migrate from the fallopian tube to the uterus. The fertilisation of an egg takes about 20 minutes until the sperm has penetrated the protective egg membrane.

The egg cells now divide daily and develop into so-called morula (mulberry germs).

The lining of the uterus is prepared for implantation of the fertilised eggs.

On the 8th day, the mulberry germs develop into blastocysts, from now on referred to as "embryos". In these blastocysts, the placenta is already created by the so-called trophectoderm cells.

The embryos reach the uterus between the eighth and 15th day after fertilisation.

On day 13-15, the blastocyst hatches from the protective layer (zona pellucida) in order to continue growing and to enable contact (implantation) with the mother.

The dividing embryos initially lie freely in the uterus for approx. 5 to 7 days. Then they are evenly distributed in the uterine horns (so-called implantation chambers).

The uterine horns are two tube-like extensions of the uterus in which the puppies spend the majority of their pregnancy.

By the way, the brain is already present on the 16th day.

Between the 18th and 20th day, they implant in the uterus and the placenta begins to form.

The hormone balance and metabolism of the female dog now adjust to the changed requirements and her behaviour can also change. She often sleeps more, eats more or not at all and nausea may occur. In addition, the dog now behaves very clingy. As a rule, this reluctance to eat is only short-lived.

Each embryo now also has its permanent place in the uterus. The head has begun to develop and tiny buds form, which eventually become the front legs (day 22).The buds of the hind legs develop a day later, as do the first signs of the eyes.The embryo begins to tilt its head forwards and curls up into the classic foetal position.The internal organs form during this time.The foetal circulation has developed and the heart beats.

At 25 days, the embryos are about the size of a walnut. The ears are formed on the 26th day, the eye cover and tactile hairs are formed on the 27th day. Legs, paws and toes (still webbed at this stage) are clearly recognisable. In their current state, the foetuses are at very high risk of defects.

Placenta formation is completed around the 28th day. If the foetal membranes die before this day, they are usually resorbed inconspicuously. At the end of this embryonic period, all the important organ systems in the dog are roughly formed, the final body shape is already recognisable in its basic features and the faces take shape. The nerve cords in the spinal cord are formed.

From this point onwards, it is no longer called an embryo, but a foetus.

The heartbeat of the embryos/foetuses can be felt by experienced people.Particularly between the 24th and 28th day of pregnancy, the 1 to 2 cm large ampullae can be felt as spherical bulges by experienced obstetricians.

The bitch's protein intake is now increased by appropriate feeding and strenuous activities such as sport and visits are now avoided.

The baby blue shimmering cover over the eyes helps protect the developing eyes.

Pregnancy can be confirmed by ultrasound from day 29. By this time, the ovaries are large enough to usually be clearly visible, but still too small to determine the number of ovaries. The bitch may be secreting thick, clear to milky mucus, which is usually a sure sign of pregnancy.

Swelling of the bitch's vulva is also noticeable. The bitch's teats begin to erect and turn pink. She will stop lifting her legs as her weight increases.
as her weight increases and the puppies turn. There may also be an increased need to sleep.

The foetus undergoes another exciting and delicate development on day 31/32. This is when the umbilical hernia occurs, which is when the intestines are temporarily pushed out of the body cavity to help it grow faster.

The uterus initially shows ovoid amniotic sacs, which "flow together" around the 33rd to 35th day and grow into tubes. The uterus folds, as the space required by the puppies is enormous.

Caution! The organogenesis (organ formation) of the puppies is completed around the 35th day. Until then, the puppies are extremely sensitive to external influences such as medication (e.g. worming treatments!), vaccinations, X-rays, vitamin deficiency and oversupply, overheating (e.g. in the car) and environmental pollutants (e.g. fertilisers in puddles), as the foetus is directly connected to the mother through the umbilical vein and artery.

Particular attention should therefore be paid to negative influences on the bitch during this period, as otherwise malformations or foetal death may occur!

On the 35th day, the eyes and ears are fully developed and the fingers are separated.

The eyelids are now formed and the fingers are fully separated and spread. Whiskers and claws begin to develop, as do the shape of the palm and the eyebrows. Skin pigmentation and coat colour also begin to develop and are completed by the 52nd day. The foetuses now look like dogs and the male sex can be determined (day 35). They are now fairly resistant to disturbances in development. The foetuses weigh approx. 6 grams and are approx. 45 mm long. The bitch is familiarised with the puppy box. Meals should be divided into 3-4 smaller portions. The bitch's nipples become darker in colour and enlarge. Good musculature is important for a smooth birth, so the bitch should continue to have sufficient exercise. However, extreme exertion such as jogging with the bitch, cycling, swimming in cold water etc. should be avoided. The bitch may become a little lazier on walks and no longer enjoy playing with other dogs. She protects her flanks and no longer lets strange dogs get close to her.

The heartbeat can no longer be used as a diagnostic method due to the increasing fluid in the uterus. On the 40th day, the intestines are moved back into the body cavity.

The picture shows a Chihuahua puppy.

The last third of the pregnancy has begun. The foetuses are now growing very quickly. Three quarters of the foetuses' growth occurs in this last trimester.

If the bitch is carrying an average or large litter, the uterine horns will fold, drastically changing their outer lines. This change is not visible when there are only two to three puppies.

Calcification begins in the previously cartilaginous bones of the foetuses. The puppies can now be easily felt under the abdominal wall, but are difficult to count. The hair on the female dog's belly is falling out. The bitch should now not play rough games with other dogs or jump.

The number and size of the puppies can be determined by x-ray.

The picture shows a small bullmastiff.

The foetus hangs from the umbilical cord like a space traveller in space and moves freely in the amniotic fluid-filled bladder. So it is fantastically stable.

His coat is still sparse, but the final pigmentation is already complete. The auricles are fully developed and the typical features - such as the Mastiff's wrinkled face - can be recognised long before birth. The foetuses are already panting in the womb, which protects them from overheating even before birth, as they lack sweat glands.

You slowly notice an increase in the size of the female dog, a thickened mammary gland and an increased appetite. The belly enlarges and her total weight can increase by 20 to 30 % during the gestation period.

From this point, the puppies can be born safely, the lungs and other important vital functions are developed ready for birth.

Eyelids and auditory canals are still closed. The last four days in the uterus serve to develop the characteristics more strongly, the puppies gain a lot of weight again and are already sensitive to touch and will enjoy it if you regularly stroke the bitch's belly.

The bitch is less hungry, which is caused by the lack of space in her belly. She spends much more time grooming herself. The teats continue to swell and the first milk may be produced.

The female dog becomes more restless and looks for a suitable place to whelp. The movement of the puppies in the womb is easily recognisable if you carefully place the flat of your hand on the dog's belly. She must be completely relaxed for this.

The bitch becomes restless and begins to show nest-building behaviour. She looks for a suitable place to litter, digs burrows, scratches around everywhere, pants. A white vaginal fluid may be secreted.

Signs of the impending birth:

• One day before the birth, hip bones become recognisable because the fruit settles. The ligaments of the uterus give way, the puppies are prepared for birth and brought into position
• many bitches refuse to feed
• when the body temperature drops by 1.5 to 2°C, the puppies are born within the next 6 to 24 hours.
• the dog formates and seeks the whelping box 
• the dog increases restlessness and is panting significantly more, uncertain expression/absence, is digging new whelping burrows in the garden or under bushes
  constantly runs in and out... empties bladder and bowels, lies down again... runs off again...
  if you look closely you can already recognise the contractions
• the dog is licking the vulva and mucous excretions, swallows frequently, is tremblingwhimpering; duration approx. 6 to 12 hours

Most puppies are born between the 60th and 65th day. The vet should be consulted on the 66th day at the latest to check the possibility of a disorder.

Now I understand that birth and the creation of new life is often referred to as a miracle. It is always a miracle that everything happens in such a way that in most cases viable puppies are born with everything in place. Just imagine if the intestines were not reabsorbed into the body...

The age of a litter is often 3-4 days apart because the eggs were not all ready for fertilisation at the same time, so this time often explains the slightly different development in birth weight and, for example, the time of eye opening.