ALAT Animal Health and Biology 2 — Questions and Answers
Question 1: What is the normal respiratory rate range for an adult mouse?
- 10-30 breaths/min
- 60-220 breaths/min (Correct answer)
- 200-400 breaths/min
- 500-700 breaths/min
Correct answer: 60-220 breaths/min
Adult mice have a normal respiratory rate of approximately 60-220 breaths per minute due to their high metabolic rate.
Respiratory rates in laboratory animals are inversely correlated with body size. Mice have high surface-area-to-volume ratios requiring rapid gas exchange. A rate of 60-220 breaths per minute is normal for adult mice at rest. Deviations can indicate respiratory disease, pain, or environmental stress.
Question 2: Which clinical sign in a rat most strongly suggests dehydration?
- Chromodacryorrhea
- Skin tenting over the scruff (Correct answer)
- Barbering of cage mates
- Bruxism
Correct answer: Skin tenting over the scruff
Skin tenting (decreased skin turgor) is a classic clinical sign of dehydration. When the skin is pulled and released, it remains elevated or returns slowly in dehydrated animals.
Skin turgor testing is standard for assessing hydration status in laboratory animals. In a well-hydrated rat, skin pulled over the scruff snaps back immediately. In dehydrated animals, the skin remains tented. Chromodacryorrhea indicates stress, barbering is behavioral, and bruxism indicates contentment in rats.
Question 3: What is the primary function of the cecum in rabbits?
- Bile storage and secretion
- Fermentation of fibrous plant material (Correct answer)
- Absorption of fat-soluble vitamins
- Production of reproductive hormones
Correct answer: Fermentation of fibrous plant material
The rabbit cecum is a large fermentation chamber where symbiotic microorganisms break down cellulose and other fibrous plant materials.
Rabbits are hindgut fermenters with a cecum that can hold up to 40% of their total GI contents. The cecum contains diverse microbes that ferment cellulose and produce volatile fatty acids and B vitamins. This process also produces cecotropes that rabbits reingest for nutrients.
Question 4: Which blood collection site is most commonly used for routine sampling in mice?
- Jugular vein
- Submandibular vein (Correct answer)
- Femoral artery
- Tail artery
Correct answer: Submandibular vein
The submandibular (facial) vein is the most commonly used site for routine blood collection in mice, allowing quick sampling with minimal restraint.
Submandibular blood collection has become the standard routine method for mice because it is quick, requires minimal restraint, yields adequate volumes, and causes minimal distress. The technique involves using a lancet to puncture the submandibular vein behind the mandible.
Question 5: What does a hunched posture in a laboratory rodent typically indicate?
- Normal resting behavior
- Dominance display
- Pain or discomfort (Correct answer)
- Preparation for mating
Correct answer: Pain or discomfort
A hunched posture in rodents is a well-recognized indicator of pain or discomfort and is a key component used in grimace scales for pain assessment.
Hunched posture is one of the most reliable behavioral indicators of pain in laboratory rodents, included in validated tools such as the Mouse Grimace Scale and Rat Grimace Scale. Other pain indicators include piloerection, orbital tightening, and reduced activity.
Question 6: What is the average gestation period for a guinea pig?
- 21 days
- 31 days
- 59-72 days (Correct answer)
- 112 days
Correct answer: 59-72 days
Guinea pigs have a relatively long gestation period of 59-72 days compared to other laboratory rodents, resulting in precocial offspring born fully furred with open eyes.
The guinea pig gestation of 59-72 days is notably longer than mice (19-21 days) or rats (21-23 days). This allows for greater fetal development, producing precocial young capable of eating solid food within days. Dystocia is a concern in females first bred after 7-8 months of age.
ALAT Animal Health and Biology 2
What is the normal respiratory rate range for an adult mouse?