Part 3. Principles, minimum standards and recommendations

This is Part 3 of the Code of Practice for the Housing and Care of Laboratory Mice, Rats, Guinea Pigs and Rabbits.

Mice and rats

The laboratory mouse and rat are derived from a largely nocturnal burrowing and climbing ancestor who favoured building nests for temperature regulation and reproduction. As such, they retain many of the traits of their wild counterparts, for example, grooming, exploratory activity, searching for food, burrowing, climbing and gnawing. Housing systems should aim to encompass these behavioural and physiological needs.

These animals have relatively poorly developed vision, but highly developed senses of smell and hearing. Rats, in particular, are very sensitive to ultrasound.

Laboratory rats and mice are very social animals, and as such, disruption to groups should be minimised. Young rats, in particular are very exploratory and active, and interact socially to an enormous degree.

Guinea pigs

Guinea pigs may appear nervous but are tame and can be handled easily. Vocalisation appears to play an important part in guinea pig social and sexual behaviour, and they often call for attention from animal care staff. They naturally thrive in family or weaner groups, and although male guinea pigs may fight, aggression between sexes is uncommon.

Guinea pigs can be housed for breeding in pairs or harems and the young are fully developed at birth. Weaning takes place at 2 to 3 weeks, but generally the young are eating solid food and water within a few days of birth.


Comparative studies of domesticated rabbits living in groups in large enclosures have shown that they retain a wide behavioural repertoire, similar to their wild ancestors.

There is increasing evidence to show that rabbits denied the freedom of natural behaviour and exercise can lose normal locomotor activity and suffer skeletal abnormalities. Within the practicalities of laboratory housing of rabbits, an environment adequate to allow performance of a wide behavioural repertoire should be provided.

The rabbit is a naturally gregarious species so attention should be paid to their social wellbeing. These requirements are preferably met by housing rabbits in pens.

Page last updated: 14 Jul 2020