Breeding - Pregnant Rats and their Litters
By LeAnn Boardman, Rattie Rascals
#1 – PLAN
There are usually many rats available for purchase and adoption in different
areas. Check into the demand for pet rats before breeding. Find out what
other breeders in your area are doing and specializing in. Are they having
any difficulty placing babies? If they specialize in a certain variety or
color, it could be in your best interest to choose to work with a different
variety or color. Maybe consider working with a color that would be
compatible with theirs. Have a back-up plan for homing babies.
Make sure you always have space to keep babies you cannot find homes for.
#2 – Preparations
If you still decide to breed, read and learn all you can about rat
genetics. Join local club(s) and get involved, which in turn will allow you
to network with breeders in your area. Purchase the best pedigreed rats in
the variety/colors you want to breed.
#3 – Marketing
Besides networking with other breeders it helps to find a way to advertise
your new rattery. A website is ideal. You will need to keep it up to date
with photos of your rats, babies available and give people an idea about
Female rats can get pregnant very young. It’s best never to keep males and
females together past the age of 6 weeks. Best breeding age should be based
on the size of the female: As long as the female is sufficiently grown, 4
months at the earliest with 6 – 7 being optimal. Females in good health and
body structure can be as bred as late as 10 months and later depending on
the genetic line. If you are not familiar with the line you are breeding,
it might be best to breed the doe earlier.
Male rats are generally good breeders at the
age of three months. However, unless you are completely aware of the
genetic ancestry of the male, it is best to not use him until you are fully
aware of what his health and temperament will be like as an adult.
Plan your breeding pairs to better your current generation and produce
offspring with desirability for placing in homes. This includes not only
colors and markings but also health and temperament. See “Selecting
a Mate Chart” for an idea on helping you
Placing them together:
There are two main ways to introduce males and females. One is “hand
breeding” which means the female is only introduced to a male on the day she
is in “heat.” The pair spends several hours together in a single cage.
The other way is placing the male and female together for an extended period
of time that insures she is with the male for one to two estrus cycles.
Since female rats cycle every 3-4 days, this could mean a period of 4-10
days or longer together, preferable not more than 14 days. Female rats can
conceive immediately after giving birth as they will go into estrus at that
Rats have a gestation of 21-23 days. We’ve typically experienced 23 days in
most of our females. Most of the time you will be able to tell the female
is indeed pregnant by 14 days into the gestation. It is nice to place the
expecting doe into a separate cage about 7-5 days away from the event. This
gives her time to become acquainted with her new surroundings.
Cage for birth & babies:
The cage the female will give birth in can be a wire cage, an aquarium or a
good size opaque plastic bin with mesh vents. The cage should be large
enough for the mother and growing, busy babies. Besides food and water you
can offer a nest box. However, this may make it difficult to check on the
mom rat and babies during birth.
Soft bedding should be used. We offer strips of newspaper and
newspaper on the floor. All our rats use a litterbox. It
is usually best to stay away from smaller wood chips as they may cut the
soft baby skin. Also, never use tissue paper as it will stick to the damp
newborns and can smother them. You can use torn paper towel strips. Cloth
as long as it does not have loose threads is also ok. Loose threads can
become wrapped around the babies causing lose of limbs or life.
Signs of labor:
Nest building – Some females begin nest building early but many do not
build nests until hours before birth. Some never build any nest. Nests
usually consist of piling all the bedding material into one area and then
making a divot to crawl up in.
Spotting of blood – If you see blood, expect the babies within hours.
Labor contractions – females may stretch out and their sides will
constrict. They will also try to reach their vulva to clean themselves of
This may or may not be witnessed. Many rat moms give birth at night.
The first sign will be some blood. Using white paper towels makes it easier
to see the blood. Labor can take anywhere from an hour to hours. If
nothing happens after 10 hours and there is blood on the bedding, it is best
to see a vet. Once a baby is born, the mom rat will clean it up and eat the
placenta. There should be a placenta with each newborn.
Not all rat moms are the same. Some like to
stay in one place, remain calm and relaxed through the entire birth
process. Others like to roam the cage and try to find a comfortable
During the birth:
It is best to allow the mom to be alone with her newborns unless there is a
problem. As long as the female is on her nest with the babies under her
there is no reason to disturb them for 24 hours. If you suspect problems
Scattered babies - One problem can be that the babies are scattered
about the cage rather than in a single nest. If the mom is still in labor
you can collect the pinkies and keep them gently warm or best yet, try
placing them in the nest area. If there was no nest made, try making one in
the area the doe favors and place them in that location.
Female not staying on nest - Sometimes a female will not feel attached
to the babies and stay in the nest and nurse the babies. You can verify
that the babies are being nursed by white milk bands across their tummies.
If the female is no longer in labor and staying away from the babies try
placing them together in a tight confined area. A small Kritter Keeper type
plastic carry cage works well. Basically this forces the doe to sit upon
the babies and they know what to do.
No milk – Several hours after the birth, if there
are no white milk bands on the babies the female may not be lactating.
Try the suggestion of placing them into a confined space to verify that the
doe is not lactating. Give them some time as her milk may still need
to come in. While she is with the babies it would be a good idea to
call around to find a foster mom or round up supplies to nurse the babies
yourself. This method is very difficult and many of the infants will
probably not survive.
After the birth:
Verify that there are no dead babies, if so, they may be removed. As long
as things have gone well you can let the mom and babies be for at least 24
hours. After 24 hours, check again to see that all the babies have milk
bands. Some may be fuller than others. Pull out any bloody paper towels
and/or bedding. Give the mom rat some fresh bedding materials.
Care and feeding of mom rat:
A good healthy diet is recommended before, during and after birth. Any
foods that you offer during gestation should not cause the mom or her
cagemates to become fat. During lactation extras can include a small amount
of dried quality kibble added to her regular food mix or you can offer her a
kitten milk replacer (KMR) step 2 mixture. Make this by taking a heaping
teaspoon of the powder mixed with warm water, cream of wheat cereal and rice
cereal for infants, this should be a thin gruel. This mix is also great for
the babies once the open their eyes. Thick oatmeal or rolled barley make
easy to eat first solid foods for babies.
After 24 hours the babies can be handled. Do be careful of the mom rat’s
attitude towards your hands. You may need to lure her off the nest to reach
them. At about three days you can even sex the babies. Before two weeks
and before the babies open their eyes they do not really need to be handled
everyday. Try to at least make your presence known to them by reaching in a
touching them. At two weeks their eyes will open. Allow them to smell your
hands. When they start to walk around really well between 2-3 weeks they
will like to eat the KMR mixture. You can even dip your fingers into it so
they can lick it off to learn what it is. The babies will be eating the
same foods as their mother so make sure they have easy access to the food
dish all day long and that the water is within their reach.
Between 4.5 - 6 weeks of age the babies can be weaned. Mom rat may have
started this process herself. You can give the mom rat breaks from them if
she seems stressed out from them following her around by placing in for
visits with her old cagemates. If the babies are less than 6 weeks of age
all the babies may stay together. After 6 weeks, separate the males from
the females. Ensure that all have plenty of food and water available to
them. You may, if you desire, to continue to offer the KMR mixture.