ALAT ALAT Species-Specific Care and Experimental Models Questions and Answers 4 — Questions and Answers
Question 1: Which of the following best describes the normal estrous cycle length in female rats?
- 4-5 days (Correct answer)
- 7-10 days
- 14-16 days
- 21-28 days
Correct answer: 4-5 days
Female rats have a short estrous cycle of approximately 4-5 days, cycling through proestrus, estrus, metestrus, and diestrus.
Question 2: A rabbit is observed pressing its abdomen against the cage floor and grinding its teeth. These signs most likely indicate:
- Normal resting behavior
- GI pain or discomfort (Correct answer)
- Reproductive readiness
- Thermoregulatory behavior
Correct answer: GI pain or discomfort
Teeth grinding (bruxism) and hunched posture with abdominal pressing are classic signs of gastrointestinal pain in rabbits.
Question 3: Which species is considered an obligate nasal breather and is particularly susceptible to upper respiratory infections that can quickly become life-threatening?
- Guinea pig (Correct answer)
- Hamster
- Gerbil
- Mouse
Correct answer: Guinea pig
Guinea pigs are obligate nasal breathers, making upper respiratory infections especially dangerous as they cannot compensate by breathing through their mouths.
Question 4: In a xenograft tumor model, which type of mouse is most commonly used as the host?
- C57BL/6 immunocompetent mice
- Athymic nude mice or SCID mice (Correct answer)
- BALB/c mice
- DBA/2 mice
Correct answer: Athymic nude mice or SCID mice
Xenograft models require immunodeficient hosts such as athymic nude or SCID mice so that human tumor cells are not rejected.
Question 5: What is the primary reason gerbils are used in cerebral ischemia research?
- They lack a complete Circle of Willis, making unilateral carotid ligation effective (Correct answer)
- They have an exceptionally large hippocampus
- Their blood-brain barrier is highly permeable
- They are resistant to anesthesia complications
Correct answer: They lack a complete Circle of Willis, making unilateral carotid ligation effective
Gerbils naturally lack posterior communicating arteries completing the Circle of Willis, so ligating one carotid artery reliably produces unilateral brain ischemia.
Question 6: A technician notices that a group of newly received hamsters are sleeping in a pile and feel cold to the touch despite a room temperature of 65°F (18°C). The most likely explanation is:
- They are experiencing heat stress
- They have entered torpor due to low ambient temperature (Correct answer)
- They are exhibiting normal social grooming
- They are suffering from a viral infection
Correct answer: They have entered torpor due to low ambient temperature
Hamsters can enter torpor (a hibernation-like state) when ambient temperatures drop below approximately 65°F (18°C), reducing their body temperature and metabolic rate.
Question 7: Which of the following is a key anatomical difference between cats and most other laboratory animal species that affects drug dosing and metabolism?
- Cats lack a functional liver
- Cats are deficient in glucuronyl transferase and cannot glucuronidate many compounds (Correct answer)
- Cats have an unusually high glomerular filtration rate
- Cats cannot metabolize proteins
Correct answer: Cats are deficient in glucuronyl transferase and cannot glucuronidate many compounds
Cats have a deficiency in hepatic glucuronyl transferase, making them unable to efficiently glucuronidate many drugs, leading to toxicity at doses safe for other species.
ALAT ALAT Species-Specific Care and Experimental Models Questions and Answers 4
Which of the following best describes the normal estrous cycle length in female rats?