15. Housing and husbandry
What to write
Provide details of housing and husbandry conditions, including any environmental enrichment.
Explanation
The environment determines the health and wellbeing of the animals, and every aspect of it can potentially affect their behavioural and physiological responses, thereby affecting research outcomes1. Different studies may be sensitive to different environmental factors, and particular aspects of the environment necessary to report may depend on the type of study2. Examples of housing and husbandry conditions known to affect animal welfare and research outcomes are listed in Table 1; consider reporting these elements and any other housing and husbandry conditions likely to influence the study outcomes.
Environment, either deprived or enriched, can affect a wide range of physiological and behavioural responses3. Specific details to report include, but are not limited to, structural enrichment (e.g., elevated surfaces, dividers); resources for species-typical activities (e.g., nesting material, shelters, or gnawing sticks for rodents; plants or gravel for aquatic species); and toys or other tools used to stimulate exploration, exercise (e.g., running wheel), and novelty. If no environmental enrichment was provided, this should be clearly stated with justification. Similarly, scientific justification needs to be reported for withholding food and water4 and for singly housing animals5,6.
If space is an issue, relevant housing and husbandry details can be provided in the form of a link to the information in a public repository or as supplementary information.
| Information to report | Examples of effects on laboratory animals |
|---|---|
| Cage/tank/housing system (type and dimensions) | Affects behaviour7 and fear learning8. Tank colour affects stress in aquatic species9,10. |
| Food and water (type, composition, supplier, and access) | Affects body weight, tumour development, nephropathy severity11, and the threshold for developing parkinsonian symptoms12. Maternal diet affects offspring body weight13. |
| Bedding and nesting material | Affects behavioural responses to stress14 and pain15. |
| Temperature and humidity | Modifies tumour progression16. Regulates sexual differentiation in zebrafish17. |
| Sanitation (frequency of cage/tank water changes, material transferred, water quality) | Affects blood pressure, heart rate, behaviour18. Adds an additional source of variation19,20. |
| Social environment (group size and composition/stocking density) | Compromises animal welfare21. Induces aggressive behaviour22,23 and stress10. |
| Biosecurity (level) | The microbiological status of animals causes variation in systemic disease parameters24. |
| Lighting (type, schedule, and intensity) | Modifies immune and stress responses25. |
| Environmental enrichment | Reduces anxiety26,27, stress26,27, and abnormal repetitive behaviour28–30. Reduces susceptibility to epilepsy31 and osteoarthritis32 and modifies the pathology of neurological disorders33. Increases foraging behaviour in fish34. |
| Sex of the experimenter | Affects physiological stress and pain behaviour35. |
Examples
‘Breeding colonies were kept in individually ventilated cages (IVCs; Tecniplast, Italy) at a temperature of 20°C to 24°C, humidity of 50% to 60%, 60 air exchanges per hour in the cages, and a 12/12-hour light/dark cycle with the lights on at 5:30 AM. The maximum caging density was five mice from the same litter and sex starting from weaning. As bedding, spruce wood shavings (Lignocel FS-14; J. Rettenmaier und Soehne GmbH, Rosenberg, Germany) were provided. Mice were fed a standardized mouse diet (1314, Altromin, Germany) and provided drinking water ad libitum. All materials, including IVCs, lids, feeders, bottles, bedding, and water were autoclaved before use. Sentinel mice were negative for at least all Federation of laboratory animal science associations (FELASA)-relevant murine infectious agents… as diagnosed by our health monitoring laboratory, mfd Diagnostics GmbH, Wendelsheim, Germany’36.
‘Same sex litter mates were housed together in individually ventilated cages with two or four mice per cage. All mice were maintained on a regular diurnal lighting cycle (12:12 light:-dark) with ad libitum access to food (7012 Harlan Teklad LM-485 Mouse/Rat Sterilizable Diet) and water. Chopped corn cob was used as bedding. Environmental enrichment included nesting material (Nestlets, Ancare, Bellmore, NY, USA), PVC pipe, and shelter (Refuge XKA-2450-087, Ketchum Manufacturing Inc., Brockville, Ontario, Canada). Mice were housed under broken barrier-specific pathogen-free conditions in the Transgenic Mouse Core Facility of Cornell University, accredited by AAALAC (The Association for Assessment and Accreditation of Laboratory Animal Care International)’37.
Training
The UK EQUATOR Centre runs training on how to write using reporting guidelines.
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