Feeder Mice

Question
Recently I've taken an interest in getting a pet mouse, and so far I have all the materials. Well... Except for the food and the mouse. Since I'm paying for the entire thing myself (minus the cage, my parents paid 5 bucks for a 2'x1' wire cage) I need everything to be as cheap as possible. I went to the pet store closest to my house to look at prices, and they only had feeder mice. They are only $1.50 each so I was wondering if I can keep feeder mice as pets and how to tell if they are girls or boys.

PS - Do you think my cage would be big enough for 2 mice?

Answer
Hi Emily,

Yes, you absolutely can keep feeder mice as pets!  There is no difference between feeder mice and fancy mice except coat color.  They are the same species and frequently bred and raised the same (unless you are purchasing from a responsible breeder, who may be able to supply friendlier mice of a specific coat type, thanks to having the time to handle each pup by hand).  My first pet mice were feeders and they were wonderful!

You will be able to determine their gender by looking underneath their tails.  Females have little to no fur between their urogenital opening (where they pee) and their anus, so it looks kind of like a semicolon ; very close together.  A male mouse has a larger furred space between his urogenital opening and anus where the testicles are housed, so it will look like he has a pouch in between the two.  When lifted upward by the tail his testicles may disappear temporarily into his body, so the best way to see them is when he is perched on something like a food bowl.  In a mature male, the difference should be very obvious once you know what to look for!  Check out these links for pictures:
http://www.fancymice.info/sexing.htm
http://www.fancymice.info/sexingcait.htm

If males and females are housed together, there is a high possibility the females may become pregnant.  This could present a problem for your cage situation, as male offspring won't be able to live with mom or other females as of 4-5 weeks old.  If they are kept separated, then a small group of females (3-4) will be happiest together.  Otherwise, you may elect to get a male.  Boy mice are best kept alone as pets, since males tend to fight with each other and may even kill each other as they reach sexual maturity.  I tend to find that although they may produce a stronger smell than females, boy mice are a little more friendly with their owners, though every mouse is an individual and won't all behave the same.

The last thing I would caution is to be sure your new pet(s) cannot squeeze their head through the bars.  If their head can fit through, the rest of their body can, and then you may have a mouse on the run!  The bars are spaced differently for mice than for say rats or hamsters, so I just wanted to make sure you knew what to check for.

Congratulations on your new pet or pets, and welcome to the world of mice!  :)
-Tam