Weaning miceWeaning miceWeaning miceWeaning mice

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 startCheck 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.

Date PrincipalInvestigator’s Name

Types of ServiceCage Separation (# of cages)

Types ofServiceOther 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 It isn’t so easy to sex pupspups

Male

Female

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

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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

Male Female

Female Male

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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 cardsThe 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.

Boston University Medical Campus Laboratory Animal Science Center

Special Services Log

Room No. Year: Date Principal

Investigator’s Name

Types of Service Cage Separation (list the number of new cages created only)

Types of Service Other Services

Number of Hours

Performed By (Print Name)

Initials

8/11 Smith 3 35 min

Shomer NS

The end