Weaning mice

Remove weaning-age mice (usually 21 days) from the parent cage. Separate the pups by sex. Mark the parent cage with a separation card; mark the weaned cages with separation stickers

Before you start Check the problem log to see if you expect to have any separations Check the room for green OC cards

Before you start Check your watch!! What time is it? If you don’t have a watch, check the time on your pager

Why are you checking the time? So you can fill out the Special Services Log when you are done. DatePrincipal Investigator’s Name Types of Service Cage Separation (# of cages) Types of Service Other Services Number of Hours Performed By (Print Name) Initials

Before you start Double-check the OC card –Is it a supervisor check? –Double-check that the weaning due date is correct- look at the weaning date calendar.

Weaning mice Remove weaning-age mice (usually 21 days) from the parent cage. Separate the pups by sex. Complete the necessary paperwork

Can you tell sex by color?

Can you tell sex from how they’re dressed?

We determine the sex of mice by examining the genitals

For pups, the ano-genital distance is used to determine sex. It isn’t so easy to sex pups Male Female

The ano-genital distance is longer in males than in females

Female pups have a shorter anogenital distance Female pups have nipples (which may not be visible if the pups are furry)

What sex is this pup? Male Female l l

Sex pups 2 at a time If they look the same, try again until you get one that looks different. The one with the longer anogenital distance is the male. The other is the female. Keep one pup of known sex, and use it to compare against the rest of the pups.

What sex is this pup? Female Male

What sex is this pup? Female Male

Male Female

Female Male l l

Weaning set-up Parent cage Male pup cage Female pup cage Even if you have more than 10 pups, start by separating the pups by sex into two cages.

Put some food on the floor for the pups

Housing pups 5 females per cage 4 males per cage Recheck the sex Put pellets of food on the cage floor Complete the green separation cards and stickers House the separated cages on the separation shelf

Separation cards The white sticker (with the separation number) goes on the green card. Write the date and the number of new cages created on the white sticker

Write the separation number on –The white cage card –Each of the green separation stickers

Put the separated cages on the separation shelf

Before you finish Update the census Initial the ‘addressed’ column in the problem log Fill out the Special Services Log.

Update the census Write the number of new cages created in the plus (+) column of the census.

Initial the ‘addressed’ column in the problem log

Fill out the Special Services Log. Fill out the Log. Put the number of new cages created in the separation column. Look at your watch to determine the time to complete the separation. The whole time (including paperwork) counts.

The end