ALAT Animal Identification Techniques — Questions and Answers
Question 1: Which permanent identification method involves creating a unique pattern of holes or cuts in a rodent's ear?
- Subcutaneous microchip implant
- Ear notching or punching (Correct answer)
- Tail tattooing
- Toe clipping
Correct answer: Ear notching or punching
Ear notching or punching creates a pattern of holes/notches that uniquely identifies individual animals or litters. It is one of the most common permanent ID methods for laboratory rodents and can encode numbers using position on left vs. right ear.
Question 2: What is the most reliable method for sexing neonatal mice when external genitalia are not yet differentiated?
- Coat color at birth
- Body weight comparison
- Anogenital distance (Correct answer)
- Presence of nipples
Correct answer: Anogenital distance
Anogenital distance (the space between the anus and the genital papilla) is the most reliable indicator in neonates: males have approximately twice the anogenital distance of females. Nipples and coat color are not reliable sex indicators in newborn mice.
Question 3: Which identification technology uses a radio-frequency device implanted subcutaneously that emits a unique number when scanned?
- Ear tag
- Transponder (microchip) (Correct answer)
- Tattoo ink
- Paint mark
Correct answer: Transponder (microchip)
A transponder (microchip) is a radio-frequency identification (RFID) device implanted under the skin. It is read electronically by a handheld scanner, provides permanent non-visible identification, and does not alter the animal's external appearance.
Question 4: In the standard AALAS mouse ear-notch numbering system, notch positions in the RIGHT ear represent which values?
- Hundreds (100, 200, 400, 800)
- Tens (10, 20, 40, 80)
- Single digits (1, 2, 4, 8) (Correct answer)
- Half-digits (0.5, 1, 2, 4)
Correct answer: Single digits (1, 2, 4, 8)
In the standard system, right-ear notch positions represent single-digit values (1, 2, 4, 8) and left-ear positions represent tens (10, 20, 40, 80). Combining positions allows identification of individuals up to number 159.
Question 5: Which of the following is a TEMPORARY animal identification method?
- Subcutaneous microchip
- Ear tattooing
- Fur clipping or marking (Correct answer)
- Ear punching
Correct answer: Fur clipping or marking
Fur clipping or marking with non-toxic dye is temporary because fur regrows, eliminating the mark. Permanent methods include ear tattooing, ear notching, and microchip implantation. Temporary marks are only appropriate for short-term studies.
Question 6: A technician receives a shipment of adult rats and must confirm their sex before housing. Which external feature is most useful?
- Ear size and shape
- Anogenital distance and presence of a scrotal sac in males (Correct answer)
- Body weight alone
- Coat texture
Correct answer: Anogenital distance and presence of a scrotal sac in males
In adult rats, sex is confirmed by anogenital distance (longer in males) and, in mature males, by the visible scrotal sac. Body weight can overlap between sexes of different ages, and ear or coat features are not sexually dimorphic features used for sex determination.
ALAT Animal Identification Techniques
Which permanent identification method involves creating a unique pattern of holes or cuts in a rodent's ear?