Animal research: Reporting in vivo experiments: The ARRIVE guidelines



 ItemRecommendation (Kilkenny et al., 2010)
TITLE 1Provide as accurate and concise a description of the content of the article as possible.
ABSTRACT 2Provide an accurate summary of the background, research objectives, including details of the species or strain of animal used, key methods, principal findings and conclusions of the study.
Background 3a. Include sufficient scientific background (including relevant references to previous work) to understand the motivation and context for the study, and explain the experimental approach and rationale.
b. Explain how and why the animal species and model being used can address the scientific objectives and, where appropriate, the study's relevance to human biology.
Objectives 4Clearly describe the primary and any secondary objectives of the study, or specific hypotheses being tested.
Ethical statement 5Indicate the nature of the ethical review permissions, relevant licences (e.g. Animal [Scientific Procedures] Act 1986), and national or institutional guidelines for the care and use of animals, that cover the research.
Study design 6For each experiment, give brief details of the study design including:
 a. The number of experimental and control groups.
 b. Any steps taken to minimise the effects of subjective bias when allocating animals to treatment (e.g. randomisation procedure) and when assessing results (e.g. if done, describe who was blinded and when).
 c. The experimental unit (e.g. a single animal, group or cage of animals).
 A time-line diagram or flow chart can be useful to illustrate how complex study designs were carried out.
Experimental procedures 7For each experiment and each experimental group, including controls, provide precise details of all procedures carried out. For example:
 a. How (e.g. drug formulation and dose, site and route of administration, anaesthesia and analgesia used [including monitoring], surgical procedure, method of euthanasia). Provide details of any specialist equipment used, including supplier(s).
 b. When (e.g. time of day).
 c. Where (e.g. home cage, laboratory, water maze).
 d. Why (e.g. rationale for choice of specific anaesthetic, route of administration, drug dose used).
Experimental animals 8a. Provide details of the animals used, including species, strain, sex, developmental stage (e.g. mean or median age plus age range) and weight (e.g. mean or median weight plus weight range).
b. Provide further relevant information such as the source of animals, international strain nomenclature, genetic modification status (e.g. knock-out or transgenic), genotype, health/immune status, drug or test naïve, previous procedures, etc.
Housing and husbandry 9Provide details of:
 a. Housing (type of facility e.g. specific pathogen free [SPF]; type of cage or housing; bedding material; number of cage companions; tank shape and material etc. for fish).
 b. Husbandry conditions (e.g. breeding programme, light/dark cycle, temperature, quality of water etc for fish, type of food, access to food and water, environmental enrichment).
 c. Welfare-related assessments and interventions that were carried out prior to, during, or after the experiment.
Sample size10a. Specify the total number of animals used in each experiment, and the number of animals in each experimental group.
b. Explain how the number of animals was arrived at. Provide details of any sample size calculation used.
c. Indicate the number of independent replications of each experiment, if relevant.
Allocating animals to experimental groups11a. Give full details of how animals were allocated to experimental groups, including randomisation or matching if done.
b. Describe the order in which the animals in the different experimental groups were treated and assessed.
Experimental outcomes12Clearly define the primary and secondary experimental outcomes assessed (e.g. cell death, molecular markers, behavioural changes).
Statistical methods13a. Provide details of the statistical methods used for each analysis.
b. Specify the unit of analysis for each dataset (e.g. single animal, group of animals, single neuron).
c. Describe any methods used to assess whether the data met the assumptions of the statistical approach.
Baseline data14For each experimental group, report relevant characteristics and health status of animals (e.g. weight, microbiological status, and drug or test naïve) prior to treatment or testing.
(This information can often be tabulated).
Numbers analysed15a. Report the number of animals in each group included in each analysis. Report absolute numbers (e.g. 10/20, not 50%) (Schulz et al., 2010).
b. If any animals or data were not included in the analysis, explain why.
Outcomes and estimation16Report the results for each analysis carried out, with a measure of precision (e.g. standard error or confidence interval).
Adverse events17a. Give details of all important adverse events in each experimental group.
b. Describe any modifications to the experimental protocols made to reduce adverse events.
Interpretation/scientific implications18a. Interpret the results, taking into account the study objectives and hypotheses, current theory and other relevant studies in the literature.
b. Comment on the study limitations including any potential sources of bias, any limitations of the animal model, and the imprecision associated with the results (Schulz et al., 2010).
c. Describe any implications of your experimental methods or findings for the replacement, refinement or reduction (the 3Rs) of the use of animals in research.
Generalisability/ translation19Comment on whether, and how, the findings of this study are likely to translate to other species or systems, including any relevance to human biology.
Funding20List all funding sources (including grant number) and the role of the funder(s) in the study.


The NC3Rs gratefully acknowledges the expertise and advice that all the contributors have given to developing the guidelines. We would particularly like to acknowledge the contribution of the NC3Rs Reporting Guidelines Working Group-– Professor Doug Altman, Centre for Statistics in Medicine, University of Oxford UK, Professor David Balding, Department of Epidemiology & Public Health, Imperial College, London UK, Professor William Browne, Department of Clinical Veterinary Science, University of Bristol UK, Professor Innes Cuthill, School of Biological Sciences, University of Bristol UK, Dr Colin Dunn, Editor Laboratory Animals (Royal Society of Medicine press), Dr Michael Emerson, National Heart and Lung Institute, Imperial College, London UK, Dr Stella Hurtley, Senior Editor Science, Professor Ian McGrath, Editor-in-Chief British Journal of Pharmacology (Wiley Blackwell Publishers) and Dr Clare Stanford, Department of Psychopharmacology, University College, London UK. We would also like to thank NC3Rs grant holders, the Medical Research Council, Biotechnology and Biological Sciences Research Council (BBSRC), Wellcome Trust, Parkinson's Disease Society, British Heart Foundation and their grant holders and funding committee members who provided feedback on the guidelines; and Kathryn Chapman and Vicky Robinson (both NC3Rs) for their help with the manuscript.

-Please note: that the working group members who contributed to these guidelines were advising in their personal capacity and their input does not necessarily represent the policy of the organisations they are associated with.


The reporting guidelines project was funded by the National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs).

These guidelines are excerpted (as permitted under the Creative Commons Attribution License [CCAL], with the knowledge and approval of PLoS Biology and the authors) from Kilkenny C, Browne WJ, Cuthill IC, Emerson M, Altman DG. Animal research: reporting in vivo experiments: ARRIVE guidelines. PLoS Biol 2010; 8(6): e1000412. doi: 10.1371/journal.pbio.1000412.

These guidelines are licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this license, visit or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA.