Care of Captive Rodents - how to find the Gender of your
Have you decided to breed your pet Multimamate Mice? Want to
clear out some of your young Kangaroo Rats but the buyer
only needs females? Don't know how to find out the gender of
your Dalmatian Cavies to choose a breeding pair?
Here are some tips:
What to look for, and where, will depend on the age of your
a. Is the animal younger than three weeks old?
b. Older than three weeks but not yet ready for breeding?
c. Breeding mature, i.e. breeding age? (Breeding age in
rodents can begin as quickly as six weeks after birth!)
a. How to Determine the Gendere of Rodents Younger than Three
The best time to find the gender of rodents that are under three weeks old
is when the babies are fuzzies and at or near the eye-
opening stage. At that age males will not have nipples
showing through the fur on their bellies, but females will.
But if you wait until the fuzzies are fully three weeks old
both genders will probably have belly hair and your chore will
be much harder or impossible.
b. How to Determine the Gender of Rodents Over Three Weeks Old
But Not Yet Breeding Mature
Once young rodents are three or more weeks of age the males
and females look almost the same, the males haven't yet
developed the external genitalia that is prominent on adult
males (testicles and penis) and the nipples of the female
also have not become clearly visible. At this point the best
way to determine the animal's gender is to compare two animals
of different genders. Trial and error will be necessary.
When you look at the genitalia of two animals at this age
level and of opposite genders, both with appear to have
male organs, but males will have about twice as much distance
between the real organ and the rear end just under the tail,
that space being the place from which the testicles will
later expand. The organ-like protuberance on the female
rodent is actually the external urethra through which the
c. How to Determine the Gender of Rodents that are
Mature enough for Breeding
Once they are breeding mature, the reproductive organs of rodents
of both genders have fully developed and it is easy to
determine the gender simply by looking.
Tips on how to check the Gender of various Rodent Species
Below are a few suggested ways to safely hold your rodent so
that you can determine its gender:
1. Just Look...Simply watch the animal as it runs around.
Can you see a scrotal sac? If one is obvious, your animal is
male. See nipples? It's a female.
Not so easy with your rodent? Try this next:
2. Use the tail...If your pet rodent is one that can be
picked up by the tail, such as a rat or common mouse, grasp
the tail as near as possible to the body and lift up, making
sure that the animal's feet are still supported by your hand
or another secure surface. Try to look quickly so as to
distress the animal as little as possible, and don't use
this method on rodents with fragile tails such as Degus or
3. Cup in the Hand...Grasp the rodent with your thumb at the
base of the tail on the animal's back and use the rest of
your hand to cup the rodent into your palm, lying on its
back so that you can see the genitals. Your rodent
(probably) will be patient enough to give you time for a
fast look without biting.
4. Mouse in the Glass...Simply scoop up your small rodent
into an empty and clean glass or wide-mouth jar, cover the
jar with a book or your hand, and look all you want. This
method should work for any small rodent even if it is shy,
easily stressed, inclined to bite, or if it is a species
with fragile tails.