The Path to Puppies
From Pregnancy to Parturition
Melissa Hoernis
Terms

Pregnancy: The state
of carrying developing
embryos or fetuses in
the female body

Parturition: The
process of giving birth
to offspring
Female Reproductive Tract of Dogs
Ovary:
Place where the ova is made and
released from
Suspensory
ligament
Ovary
Oviduct: Connects the ovary to the uterus
Uterus:
Oviduct
Place that holds the growing fetuses
Cervix: Acts as a barrier to keep bacteria
from getting to the growing fetuses
Pelvic canal: The birth canal (the way the
fetuses get to the outside world)
Uterine horn
Uterine body
Cervix
Pelvic Canal
Conception: formation of an embryo
◦ An embryo is formed when the egg becomes
fertilized and starts growing from one single
cell into thousands then millions.
What about the GENES!
Genes hold the information to build and maintain an
organism's cells and pass traits to offspring
DNA

This is what is in the nucleus of a cell and is the
blueprints for the entire body
Chromosome
Gene
DNA
Number of Chromosomes

Each cell in a dog has 39 PAIRS of
chromosomes for a total of 78!
39 pairs = 78 total
Each gamete (egg/ sperm) has HALF the
genetic information needed
39 chromosomes
from the mother
39 chromosomes
from the father
78 chromosomes total
So when they combine the genetic
information is made complete!
A quick course in EMBRYOLOGY

The egg is fertilized and then
starts dividing and multiplying
EXPONENTIALLY
Then this clump of cells starts to change and
form different types of tissues that then form
organs then organ systems. This is called
differentiation.
Cell- smallest unit
Tissue- groups of cells with same general function and
texture (example: Muscle)
Organ- two or more types of tissues that combine to serve
a specific function (example: Stomach)
Organ system- several organs that work together to serve a
specific function (example: Digestive system)
Development of the embryo

What is an embryo?
An embryo is what we call the puppy from
the point when the egg is fertilized until the
body is fully developed (just miniature).
Growth of the fetus

What is a fetus?
Once the embryo is fully developed it still
needs time to grow while it is in the
mother’s womb. The fetus is what we call
the puppy once it is fully developed but still
growing.
Guess the species of each embryo!
How about now?
OKAY… How about now?
Fish Salamander Tortoise Chicken
Pig
Cow
Rabbit Human
The Placenta

The Placenta is a temporary organ
formed in the uterine wall of the mother
that is connected to the fetus via the
umbilical cord.
The Placenta

Purpose:
◦ Nutrients
 The fetus needs food to grow
◦ Gas exchange
 The fetus cannot breath but it’s body still needs
oxygen to work so the mother provides oxygen
◦ Waste elimination
Gestation Length
The length of time from
conception until birth
Let’s COMPARE
63 Days
335 Days
63 Days
270 Days
625 Days
Pregnancy

What are some signs that the female is
pregnant? (can you guess any)
◦ Weight gain (doesn’t start until week 4)
◦ Increased appetite (again not until week 4 and some
have decreased appetite at times)
◦ Nesting behavior
◦ Drop in temperature
Tools veterinarians use to diagnose
pregnancy

Radiographs
◦ Fetal skeletons seen by day 42
◦ Best way to find out how many there are

Ultrasound
◦ Beating hearts by day 25

Measurement of certain hormones
Parturition- the birthing
process
There is a
hormone
cascade and
feedback system!
It all starts with FETAL STRESS!
Positive feedback loop:
The hypothalamus (a
part of the brain) sends
a signal by way of the
hormone oxytocin to
the uterus causing
contractions. The
pressure of the fetus
on the cervix sends a
signal back to the brain
which then stimulates
the release of more
oxytocin.
Uterus
Mother’s brain
Complications

What happens if the mother cannot give
birth (puppies are too big, mother is too
tired)
◦ The veterinarian must perform a c-section
Nursing
It is extremely important for newborn
puppies to drink milk from their mother
 Not only does it provide a source of food
that is easy to digest but it also gives the
newborns immunity! (basically they are
protected from certain diseases)

Key things to monitor
in a newborn puppy




Weight gain: you want to know they are EATING (1
gram per pound of adult weight per day)
Temperature: puppies can become cold very easily
and cannot shiver until 6 days old (keep
environment at 86°F)
Mother has to help them urinate and defecate
Look for body defects
(cleft palate)
Fun facts and owner education
Open eyes from days 10-15
 Open ears from days 15-17
 Wean puppies at 3-4 weeks
 Socialization period is 4-12 weeks of age

Let’s put it all together!
Day 78 Day 84
Day 1
Day 63 Day 73
Day 91
Gestation length
Conception
Embryo
Fetus
Body fully
developed
Wean
Birth Eyes open
Ears open
Start
Socialization
In Summary…
The puppy is conceived and gets half the
genetic information from the mother and half
from the father
 The embryo develops into a fetus that grows
in the womb.
 During the birthing process there are many
hormones that are part a positive feedback
loop that ultimately cause contractions.
 Newborn puppies must be monitored closely
to ensure they are eating, gaining weight and
maintaining a proper body temperature.
