Rodent Shelter

Background

Rodents undergo surgical procedures in studies investigating disease mechanisms, the efficacy and safety of new treatments and to enable monitoring of physiological parameters such as heart rate and blood pressure. Post-operative care is critical to minimise pain and distress and aid recovery. This includes providing analgesia, a source of warmth and shelter, palatable food and close regular observations of animal behaviour and vital signs.

Following surgery, most rodents are returned to their social groups as soon as they are sufficiently recovered. In some circumstances it can be necessary to single house animals for a short period of time to mitigate against damage to sutures, wounds and implants by cage mates. When rodents are singly housed directly after surgery, enrichment items are often removed to avoid injuries and enable better monitoring. The post-operative housing environment is important as it can influence recovery in mice [1] and may induce stress. For example, a change in bedding material can affect post-surgery blood pressure [2, 3].

Rodents have a large surface area to body weight ratio, which means they lose body heat rapidly and are susceptible to hypothermia. Following anaesthesia and surgical procedures, their ability to regulate their body temperature is reduced. Providing thermal support during this time is critical to mitigate against the risk of hypothermia and aid the animal’s recovery [4-8]. Warmth is often provided by externally powered heat pads placed under the cage. However, these cannot be used for cages kept in racks (e.g. individually ventilated cages and large rat cages such as high houses or double decker cages). There is a need for an easy-to-use solution for providing shelter and warmth in any cage type for post-operative care.  

3Rs benefits

Annually at AstraZeneca, over 200 rodents undergo surgical procedures and require post-operative care. The development of a small, easy-to-use, warming shelter would improve post-operative recovery, monitoring and pain management, as well as scientific outcomes. Improved recovery could also enable:

• A reduction in rodent use, especially for advanced surgical models, where extra animals are added due to the uncertainty around post-operative recovery.
   
• Returning animals to their social groups more quickly, minimising the time spent singly-housed.

The shelter would have broad applicability across the bioscience sector where surgical animals are used including academia, contract research organisations and the pharmaceutical industry. It could also be used for non-surgical models such as cold sensitive strains (e.g. BTBR ob/ob mice and nude mice) and for mice required to be single housed for specific measurements such as food intake or in cases of male mice incompatibility. Additionally, the shelter could be used by veterinary clinics in the care of small animal pets, where there is increasing demand for veterinary care and surgical intervention.

References

1. Pham TM et al. (2010). Housing environment influences the need for pain relief during post-operative recovery in mice. Physiol Behav 99(5):663-8. doi: 10.1016/j.physbeh.2010.01.038
    
2. Baran WS (2010). Post-surgical environmental enrichment in rodents, Enrichment Record enrichmentrecord.com 
    
3. Terreros D (2010). Effect of bedding type on blood pressure lean Zucker rat. El Paso
    
4. Institute for Laboratory Animal Research (2011). Guide for the care and use of laboratory animals, 
   8th ed. Washington (DC): National Academies Press.
    
5. Tashiro M et al. (2020). Duration of thermal support for preventing hypothermia induced by anesthesia with medetomidine-midazolam-butorphanol in mice. J Vet Med Sci 82(12):1757-62. doi: 10.1292%2Fjvms.20-0256
    
6. Beale CN et al. (2018). Use of Air-activated Thermal Devices during Recovery after Surgery in Mice. J Am Assoc Lab Anim Sci 57(4):392-400. doi: 10.30802%2FAALAS-JAALAS-17-000077
    

7. Caro AC (2013). Comparison of thermoregulatory devices used during anesthesia of C57BL/6 mice and correlations between body temperature and physiologic parameters. J Am Assoc Lab Anim Sci 52(5):577-83. PMID: 24041214

8. Bagis H (2004) Exposure to warmer postoperative temperatures reduces hypothermia caused by anaesthesia and significantly increases the implantation rate of transferred embryos in the mouse. Lab Anim 38(1):50-4. doi: 10.1258/00236770460734399

9. Weary DM (2009) Board-invited review: Using behavior to predict and identify ill health in animals. J Anim Sci 87(2):770-7. doi: 10.2527/jas.2008-1297

Assessment information

Review Panel membership

A team at NestLab, led by Mr Alonso Sanchez Maltese, have developed a modular, in-cage recovery shelter for laboratory mice and rats that provides controlled warmth and non-invasive welfare monitoring following surgery.

Post-operative care is critical to a rodent's recovery and to minimising pain and distress. Following surgery, animals are often housed singly and enrichment is removed to protect wounds and implants, while rodents remain susceptible to hypothermia during recovery.

NestLab worked with the Challenge Sponsors, AstraZeneca and the University of Gothenburg, who provided end-user input and hosted the in vivo pilot studies. By combining thermal control and non-invasive sensing the shelter is able to support animals recovering from surgery without the need for additional handling. Designed around standard cage formats and routine husbandry, the Nestlab shelter for mice was tested in a laboratory setting so that it could be adopted without changes to existing racks or workflows. It is made from a durable, red-tinted transparent material that withstands repeated use and decontamination. Recovering animals can be observed without opening the cage, while the tint gives the animals a dimmer, more sheltered interior. The collaboration with the Sponsors is continuing, with further testing planned to build on the pilot study findings, including larger housing for rats.

By helping to prevent surgery-related hypothermia and reducing the handling needed to monitor recovering animals, the NestLab shelter refines post-operative care, improving the welfare of rodents during recovery while supporting more reproducible data.

For more information about NestLab and how to access the technology, visit the NestLab website.

NestLab: A modular in-cage recovery shelter for rodents

The NestLab shelter provides controlled warmth and non-invasive welfare monitoring for post-operative recovery. It is wireless and fits standard rodent cages without rack modifications.

The shelter is offered as a range of nodes which can be combined to suit users needs:

• The Essential Node provides warmth only, for comfort and recovery in everyday housing.
• The Advanced Node enables non-invasive welfare monitoring throughout recovery, including non-contact infrared surface-temperature tracking, occupancy monitoring and an on-device display, holding a set in-shelter target temperature (range: 20 to 40°C).
• A separate Monitoring Dashboard gives control and reporting across multiple units, via an encrypted Bluetooth mesh.

The same shelter adapts across three modes, post-operative, recovery and general housing, so animals can be supported from surgery through to routine housing. The NestLab shelter is autonomous, with a 48 hour battery and full recharge in 1.5 hours. It is lab-ready, with tip-over auto-shutoff safety mechanism, flame-retardant construction, CE and UKCA marking, and can be decontaminated using a dishwasher, hydrogen-peroxide or alcohol-wipe.

Challenge Sponsors AstraZeneca and the University of Gothenburg worked with the team to ensure the NestLab shelter met end-user requirements by conducting pilot studies with mice to test prototypes. Larger housing for rats is also available and underdoing testing.

Access the technology

For more information about NestLab and how to access the technology, visit the NestLab website.