At Country Style Dachshunds, this week began with our beloved Twiggy and the handsome Harley having their first and second dates. Although unseen, exciting changes have already begun.
Twiggy has ovulated and fertilization has occurred. The fertilised egg, now called an ovum, begins dividing. On day 6, each ovum divides into a two celled embryo. Day 7 and the embryos divide again and begin the journey down the fallopian tube towards the uterus.
Twiggy has finished her season and the four celled embryos are busy dividing. Eight celled embryos become sixteen celled embryos and by day 10 the embryo, now called a morula, has thirty-two cells. Day 11 and the sixty-four celled morula becomes a blastocyst.
Our gorgeous babies are approaching an important stage, and yet still look nothing like puppies. The blastocysts float freely within the uterine horns and they have grown from just a 1/4mm to 2mm across. The blastocysts space out evenly among the uterine horns and on day 19 they implant. The placenta begins to form.
This week, their hearts spring into action. Development of the brain and spinal cord begins and the head and neck bend forward. Limb buds begin to grow. The embryos’ retinas now have pigmentation. They have more than doubled in size at 5mm and, towards the end of this week, will have almost tripled in size again at 14mm. Twiggy has begun to gain weight, her ribs are wider and her stomach is lower. Mammary changes are more apparent.
This is an important week, even though the gender of the puppies was decided when the eggs were fertilized in week 1, as their male and female characteristics can now be differentiated.
From day 29, the embryos’ toes begin to form and facial features are more defined. Their nipples and whisker buds are now visible. Their umbilical cords form and the embryos are around 18mm long. Our puppies are becoming more recognisable and the pigmentation in the eyes, nose and skin has started to develop.
Twiggy is slowing down and resting more. She has a noticeable bump and is needier and cuddlier than normal. Her food preferences are changing: she is now choosing cooked chicken over raw chicken mince! By the end of this week, the embryos have nearly doubled in size again.
Our puppies, now much more puppy like, have closed their eyelids. They will not re-open now until around 6 to 10 days after birth. Internal organs and external body parts have all formed. The ears have developed both inside and out and are now sealed. They will be completely deaf for the first 10 to 14 days of their lives.
The foetuses have their toenails and skin pigmentation. Towards the end of this week they are approaching over 45mm long. Ossification, the formation of bone, is complete.
Growth of the foetuses continues. Our puppies get lots of practice for the outside world by kicking, stretching, and swallowing. Movements can now be felt, which is always an exciting time.
Twiggy is gaining more weight. Her stomach is much lower. She is preferring to exercise in the garden and stay close to home, rather than do long walks though the farm and surrounding Dorset countryside. Her food intake is increasing and as the puppies take up more room, she is eating smaller meals more frequently throughout the day.
Our puppies will now continue to grow and get stronger. Twiggy will shed most of the hair on her stomach, which will make it easier to see the foetuses move through the skin. Around day 55 the foetuses begin to grow their beautiful coats. At the end of this week, on day 57, our puppies are now viable on the outside. Although they are nearly ready, their lungs are still underdeveloped, it will be much safer for them to wait for another week.
The foetuses now fully resemble the miniature dachshunds they will grow to be. Their coats will fill out and their lungs will fully mature. As the week goes on, they will start to run out of room and turn to face the right way for delivery.
Twiggy’s belly will drop even lower as the babies nearest her rib cage move down. Twiggy will spend more time in her whelping box and begin nesting in preparation. Her milk will come in and progesterone levels will lower. Roughly 24 hours before labour, Twiggy’s temperature will drop from around 38 degrees centigrade to between 36.9 and 36.0 degrees centigrade. This is caused by reduced progesterone, which triggers the first stage of labour to begin.
Above: left a chart showing the development of puppies in the womb, right a cross section of a uterus showing a litter of ten puppies in their amniotic sacks.
Some photos in this blog were sourced from the National Geographic documentary “Animals In The Womb”, which is well worth a watch.
It follows the gestational development of a litter of Golden Retrievers, a Bottle Nosed Dolphin, and an Asian Elephant.
We hope you are looking forward to the arrival of Twiggy’s puppies as much as we are!