fancy and deer mice

Question
I have fancy mice (females only) One day upon entering my room I saw a deer mouse jump up and squeeze out of the cage ( aquarium with mesh lid ) If it is a male deer mouse, is it possible for him to impregnate my females? I'm kind of worried because I have 4 females and I have no idea how long he has been getting in there.

Answer
Hi Sharon,

Deer mice can mate with fancy mice, but since their gestation period is 21 days you only have to wait three weeks to find out.  They should have much rounder bellies around 2 weeks if they did get prego, so provide extra feed and nesting material for just in case.

The bigger risk in my opinion is parasites.  Keep an eye on your girls to make sure no one starts sneezing or itching, and clean the cage out thoroughly.  To keep their friend out in the future, you can attach wire with 1/4 inch or smaller openings to the lid, or use clamps (available in the reptile section) to keep the lid on tight enough that no mice can squeeze out the sides.

Best of luck!
-Tam