The Three R's

information that demonstrates the principl​​​es in Section 1.1, and must balance whether the potential 

effects on the wellbeing of the animals involved is justified by the potential benefits.

throughout the animal’s lifetime, including acquisition, transport, breeding, housing, husbandry, 

use of the animal in a project, and provisions for the animal at the conclusion of their use.​

1.31 Institutions, AECs, and people involved in any aspect of the care and use of animals for scientific 

purposes must be ​​aware of and accept their responsibilities (see Section 2), and act in accordance 

with the Code.

1.18 Methods that replace or partially replace the use of animals must be investigated, considered and, 

where applicable, implemented.

including existing databas​​​es, must be examined. Replacement techniques that must be considered 

include the use of epidemiological data; physical and chemical analysis; computer, mathematical 

and inanimate synthetic models; simulations; in vitro systems; non-sentient organisms; cadavers; 

and clinical cases.

a project. Where relevant and applicable, the outcome of this review must be implemented in 

current projects and taken into account in planning future projects.

1.21 The number​ of animals used in a project must be the minimum necessary to achieve the proposed 

aim(s) and to satisfy good statistical design. The use of too few animals may invalidate the 

experimental result and result in wastage of animals.

 1.22 The number of animals used may be reduced by the appropriate re-use of individual animals. 

The benefits of reusing animals must be balanced against any adverse effects on their wellbeing, 

taking into account the lifetime experience of the individual animal. Re-use of animals requires 

particular justification and specific AEC approval.

 1.23 Activities involving the use of animals must not be repeated within a project or between projects 

unless such repetition is essential for the purpose or design of the project (e.g. sound experimental 

design, statistical analysis, corroboration by the same or another investigator).

 1.24 Reducing the number of animals used should not result in greater harm, including pain and 

distress, to the animals used.

 1.25 All possible steps must be taken to reduce factors that are not part of the experimental design of 

the project and are known to contribute to variability of experimental results, including the use 

of animals of known genetic, biological and behavioural background. Reduction of experimental 

variables may result in reduced animal use.

 1.26 Where practicable, tissue and other biological material from animals being killed must be shared 

among investigators or deposited in a tissue bank for subsequent distribution.

 1.27 Breeding of animals must be managed to avoid or minimise the production of excess animals. 

A new line of animal should not be generated if a similar suitable animal line is available to the 

investigator. When a new animal line is generated, the colony should be made available as a 

source for other investigators as appropriate.

1.28 Steps must be taken at all times to support and safeguard animal wellbeing. The effectiveness of 

strategies for suppo​​rting and safeguarding animal wellbeing must be kept under review during the 

lifetime of activities, including projects. Where relevant and applicable, the outcome of this review 

must be implemented in current activities and taken into account in planning future activities, 

including projects.

must be compatible with supporting and safeguarding animal wellbeing. Animals must not be held 

for prolonged periods as part of an approved project before their use without AEC approval.