ALAT Animal Husbandry and Environment 4 — Questions and Answers
Question 1: What is the recommended relative humidity range for most laboratory rodent housing facilities?
- 20–30%
- 30–70% (Correct answer)
- 70–90%
- 10–20%
Correct answer: 30–70%
The Guide for the Care and Use of Laboratory Animals recommends maintaining relative humidity between 30–70% for most rodent species.
Question 2: Which type of bedding material is considered most appropriate for laboratory mice to reduce ammonia buildup?
- Cedar shavings
- Corncob bedding
- Hardwood chip bedding (Correct answer)
- Newspaper
Correct answer: Hardwood chip bedding
Hardwood chip bedding (such as aspen) is preferred because it is absorbent, low in aromatic compounds, and helps control ammonia levels.
Question 3: A technician notices that group-housed male mice are showing increased aggression and wounding. Which environmental modification is the FIRST recommended intervention?
- Increase photoperiod to 16 hours of light
- Provide environmental enrichment such as huts or shelters (Correct answer)
- Lower the ambient temperature by 5°C
- Switch from static to individually ventilated caging
Correct answer: Provide environmental enrichment such as huts or shelters
Adding enrichment items like shelters gives subordinate animals refuges and often reduces aggression-related wounding in group-housed males.
Question 4: How often should water bottles and sipper tubes be changed or sanitized as a minimum standard in rodent facilities?
- Daily
- Every 2 weeks
- At least weekly (Correct answer)
- Monthly
Correct answer: At least weekly
Water bottles and sipper tubes should be sanitized at least weekly to prevent microbial contamination and biofilm formation.
Question 5: What is 'ringtail' in laboratory rats, and what environmental factor primarily causes it?
- A fungal infection caused by high humidity
- Annular constriction of the tail caused by low humidity (Correct answer)
- Tail necrosis from cage bite wounds
- A genetic condition unrelated to environment
Correct answer: Annular constriction of the tail caused by low humidity
Ringtail is annular constriction and necrosis of the tail caused by low relative humidity, most commonly seen in neonatal rats.
Question 6: Which lighting schedule is most commonly used to regulate circadian rhythms in standard laboratory rodent colonies?
- Continuous bright light
- 12 hours light / 12 hours dark (Correct answer)
- 16 hours light / 8 hours dark
- Continuous darkness
Correct answer: 12 hours light / 12 hours dark
A 12:12 light/dark cycle is the standard photoperiod used in most rodent facilities to maintain normal circadian rhythms and reproductive cycling.
Question 7: When performing a cage change for immunocompromised mice housed in individually ventilated cages (IVCs), where should the procedure be performed?
- In the hallway outside the animal room
- Inside a biosafety cabinet or laminar flow hood (Correct answer)
- In the main corridor of the facility
- Directly on the rack without any enclosure
Correct answer: Inside a biosafety cabinet or laminar flow hood
Cage changes for immunocompromised animals must be performed inside a biosafety cabinet or laminar flow hood to protect the animals from environmental pathogens.
ALAT Animal Husbandry and Environment 4
What is the recommended relative humidity range for most laboratory rodent housing facilities?