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Identification methods in newborn C57BL/6 mice: a developmental and behavioural evaluation.
M J Castelhano-Carlos1, N Sousa, F Ohl
1Life and Health Science Research Institute, University of Minho, Braga, Portugal. mjoao@ecsaude.uminho.pt
Laboratory Animals
|October 27, 2009
Summary
Identifying newborn mice is crucial for research. Toe clipping and tattoo ink puncture are suitable methods with minimal impact on development, while transponder implantation is best for older mice.
Area of Science:
- Animal models in biomedical research
- Laboratory animal science
- Rodent welfare and identification
Background:
- Group-housing of rodents necessitates individual identification for research integrity.
- Limited data exists on the developmental and welfare impacts of identifying newborn mice.
- Standard identification methods for research animals require careful evaluation for early-life application.
Purpose of the Study:
- To assess the effects of three identification methods (toe clipping, tattoo ink, transponder implantation) on newborn C57BL/6J mice.
- To evaluate the long-term efficacy and welfare implications of these identification techniques.
- To determine the impact on somatic development, neurological reflexes, behavior, and stress indicators.
Main Methods:
- Newborn C57BL/6J mice (postnatal day 5) were subjected to toe clipping, toe tattoo ink puncture, or transponder implantation.
- Reactions to procedures were recorded; toe tissue was assessed for genotyping.
- Somatic and neurological development were monitored postnatally.
- Adult behavior and sensory-motor functions were evaluated using SHIRPA, Rotarod, and Elevated Plus Maze tests.
- Postmortem thymus and adrenal gland weights were analyzed as stress indicators.
Main Results:
- All methods provided effective long-term individual identification.
- Toe clipping elicited the least distress, followed by tattoo ink; transponder implantation was most distressing.
- Toe clipping provided sufficient tissue for genotyping.
- No significant consistent differences in postnatal development or adult behavior/sensory-motor function were observed.
- Organ weights did not indicate chronic stress related to any identification method.
Conclusions:
- Toe clipping is recommended for newborn mice requiring genotyping due to its minimal impact and suitability for genetic analysis.
- Toe tattoo ink puncture is a viable alternative for newborn identification.
- Transponder implantation should be reserved for older newborns or applied at weaning to minimize distress.
