• Decide upon the characteristics of the animals that are essential for the study and for reporting.
  • Avoid generation of surplus animals.


There are three broad areas which need to be considered when planning animal studies:

  1. The suitability of the species or strain as a model of the target organism
  2. The ethical issues surrounding their use: ‘choosing the right animal for the right reason’. The large increase in use of genetically altered lines has created increasing concern about the suitability of these animals as models of human conditions.
  3. Characterisation of the animals. Items to be considered, in collaboration with the supplier, include:
    • Species, strain, line and phenotype (with an explanation of any genetic modifications)
    • Age, developmental stage, sex and weight
    • Stage of oestrous cycle and any previous breeding history
    • Any necessary pre-treatment (e.g. castration or ovariectomy) and those responsible for this
    • Name and address of the supplier/breeder, or, if wild-caught, the place, time and method of capture and transport
    • Health status (e.g. germ-free, gnotobiotic, SPF, conventional, vaccination status)
    • Re-use of animals, which should be justified and which may be regulated by national legislation
    • Any plans for release or re-homing, which may be regulated by national legislation
    • Breeding and colony management

Sharing animal tissue

Collaboration with other internal or external laboratories should be considered, to reduce the number of animals needed. Here are some resources:

Recommendations from an expert working group on the sharing and archiving of material from genetically altered mice.

Part of the planning process should be to evaluate whether human tissue can be used instead of animal material.

Steps should be taken to avoid surplus animals, such as those in breeding programmes which prove to be too old, those which respond poorly to treatment (for example by showing a weak immune response) or which are otherwise unsuitable for re-use, re-homing or release.

Information on a large number of textbooks that describe the species and strains used in animal research is available in the TextBase database on this site. Examples include The Laboratory Mouse, The Laboratory Rat and The Laboratory Fish.

More resources

This page was updated on 16 April 2021

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