Animal Welfare and Ethics

Murinova, as the equipment provider, does not itself carry out any animal procedures, and does not supply Passive Transponder Tags or implantation syringes; the information in this chapter on the tags and their implantation is relayed from the tag suppliers’ documentation. All procedures described below must be performed under a protocol approved by the Animal Ethics Committee (AEC) at the researcher’s own institution. This chapter explains how Trumouse embodies respect for animal welfare in its design and use, and may serve as a reference when researchers prepare an AEC application.

We place respect for animal welfare first. Trumouse’s identification and tracking methods are designed around minimizing pain, minimizing disturbance and preserving natural behavior, consistent with the 3Rs (Replacement, Reduction, Refinement). The following describes this from four perspectives: the implant, the implantation procedure, environmental enrichment, and site hygiene.

The Implant: Passive and Biocompatible

• The system relies on an implanted, battery-free Passive Transponder Tag for individual identification. The tag has no battery; it returns its ID when energized by the LF Reader Module’s 134.2 kHz magnetic field, in accordance with ISO 11784/11785, FDX-B.
• The tag is encapsulated in biocompatible glass and does not affect the animal’s behavior or body weight after implantation.
• The ISO 11784/11785, FDX-B tag used by this system is based on the same technical standard as the identity microchips implanted in pet cats and dogs worldwide — a technology with decades of use and a well-established record of long-term subcutaneous implantation safety.

Implantation: Minimally Invasive and Aseptic

• Implantation is comparable to a subcutaneous injection: it takes seconds, requires no incision or suturing, and the implant site typically heals within 2 to 3 days.
• We recommend performing all implantations under anesthesia. In practice, mice aged 3 weeks or older can generally also be implanted while awake and properly restrained without problems. Whether to use anesthesia, and the analgesia regimen, are decided by the researcher under the protocol approved by the institution’s AEC. See Implantation Guidance for the procedure.
• Both recommended tags are available pre-loaded in single-use implanters (see Recommended Tags); open the packaging only immediately before implantation.
• Implantation follows aseptic technique: the fur at the inter-scapular injection site is wetted with 70% ethanol to reduce hair introduction into the subcutaneous space; used needles are disposed of as sharps according to regulations.
• Researchers need not perform the implantation themselves: several laboratory-animal suppliers (for example, The Jackson Laboratory) offer microchip implantation services compliant with ISO 11784/11785, FDX-B, and some strains ship already carrying a compatible subcutaneous tag, so the animals can be identified on arrival — removing the need for local implantation and the associated restraint stress.
• Once implanted, all subsequent identification is entirely non-contact. There is no need to repeatedly handle the animals for identification purposes throughout the study, which fundamentally reduces stress.

Environmental Enrichment: Preserving Group Housing and Natural Behavior

• Non-contact identification makes group housing possible: individuals of the same strain that look almost identical can be told apart without ear tags, collars or dye marks, thereby supporting social enrichment.
• No external attachment is worn on the animal, avoiding the tissue injury caused by mice biting or scratching at external markers, and not disturbing their grooming and social behavior.
• Identification and tracking are performed passively within the animal’s home environment, without interrupting the use of nesting material and enrichment items or disrupting the established social structure.
• Because no repeated handling is needed for identification, social dynamics remain stable, which facilitates longitudinal behavioral studies.

Site Cleaning and Equipment Maintenance

• For how often and how to clean the arena, and how to transfer the mice during cleaning, see Cleaning; routine hygiene should follow the standard operating procedures (SOPs) of the institution.
• The Trumouse Reader Array (the floor reading platform) is itself splash-resistant to a degree and can be cleaned routinely by wiping with a damp cloth or disinfectant; the acrylic enclosure walls around it can be removed for more thorough cleaning.
• The system includes built-in environmental sensors that continuously log and monitor temperature, humidity, noise, light, carbon dioxide (CO₂), ammonia (NH₃) and total volatile organic compounds (TVOC), with fans ensuring good ventilation; the system raises an automatic alert whenever any reading is abnormal (per-channel specifications are given in Environmental Monitoring), helping to maintain the animals’ living environment.