Transcript Mouse cage change criteria

Mouse cage change criteria
Goals:
Provide healthy environment
Reduce animal stress
Minimize care costs
Minimize odors
Special Considerations
• Microisolator cage tops hold in waste
gases and moisture
• Small amounts of bedding dry outexcessively deep bedding stays damp
• Moisture from the water bottle is as bad as
moisture from urine
More biology than you expected
• Ammonia (NH3) is the gas of most
concern- it irritates eyes, damages lungs.
• Urine, NOT feces, is the source of
ammonia
• FRESH urine contains no ammonia
• Over time, bacteria convert the urea in
urine to ammonia
• The urine needs to be wet for this to
happen
Mouse behavior
• How do mice feel about a new, clean
cage?
Mouse poop is not the problem
• Mice like feces
• It is normal for mice to EAT feces
Movie
Urine is the problem
• Wet urine is the problem
• Water (from the water bottle) is also a
problem if it rehydrates dried urine
When do you need to change the
cage?
• When more than 25% of the bedding, as
viewed from the bottom, is wet
• When the bedding, as viewed from the
top, is wet (don’t count a fresh drip from
bottle)
• If you see any mold on the bedding or food
Five mice in a cage
3 days
7 days
M4 D7
M5 D5
M1 D10
M1 D12