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Literature Searching: How to Find Animal Use Alternatives

The National Agricultural Library's Animal Welfare Information Center (AWIC) provides guidance on building and conducting a 3Rs (replacement, reduction, refinement of animal use) alternatives literature search. This page details instructions for finding 3Rs alternatives along with other resources to assist individuals working with animals in research, testing, and teaching. 

Why Consider 3Rs Alternatives?

The Animal Welfare Act (AWA) regulations require principal investigators (PIs)/scientists to consider alternatives to procedures that may cause more than momentary or slight pain or distress to the animals. They must provide a written narrative to their Institutional Animal Care and Use Committee (IACUC) that describes the methods and sources (e.g. the Animal Welfare Information Center) used to determine that alternatives were not available (9 C.F.R. § 2.31 (d)(ii)(2022)). Additionally, PIs/scientists must also provide written assurance that their activities do not unnecessarily duplicate previous experiments (9 C.F.R. § 2.31 (d)(iii)(2022)).

A thorough literature search can identify information to meet these requirements and provide PIs with current research related to their area of study.

Table of Contents

Planning a Search

Targeted literature searching provides better results and limits irrelevant citations. Below are steps on how to conduct an alternatives literature search. You’ll find guidance on creating targeted questions, selecting databases and other resources, finding keywords, understanding search syntax tools and when to use them, and how to combine keywords and search syntax together to create a productive search string.

This checklist provides an overview of the steps for conducting an alternative literature search. Use this checklist and linked resources to stay on track as you begin literature searching.

The Checklist
  1. Review the protocol and ask targeted questions to identify areas where 3Rs alternatives could be incorporated into the research
  2. Determine which databases and/or grey literature resources (websites, journals, books, conference proceedings, etc.) are appropriate for the specific research topic
  3. Identify keywords/search terms (including synonyms) for your search and develop search strings
  4. Conduct the search and review your search results for relevancy
  5. Edit and refine your search as needed
    • Refining a search is a trial-and-error process. Your first search string likely won't yield all the information you are looking for, and you may need to use multiple search strings to help yield the best results.
  6. Save your search strings in a document and use a citation manager (e.g., EndNote, Zotero, etc.) to organize and save your citations

Step 1: Identify Areas to Potentially Implement Alternatives

The first step to building a 3Rs alternatives search is reading the study’s protocol and asking targeted questions to address areas of the protocol where 3Rs alternatives can potentially be implemented. These questions will help identify search terms and connections between concepts and provide a roadmap for the search.

Questions to Help You Get Started
  1. Are the number and species of animal appropriate for this type of research? Could this research be conducted in a non-animal model?
  2. Is the study designed to promote non-bias results? 
  3. What makes your study unique? Does it duplicate previously published research?
  4. How are animals housed during the study and is it appropriate for this species? Are there improvements/enhancements to housing and/or handling that will improve animal well-being?

  5. What procedures performed on these animals might cause physical or emotional pain or distress? Are there refinements or alternatives to these procedures? Can anesthesia or analgesia be used to minimize or eliminate the pain and distress?  How will the animals be monitored/accessed for pain and distress?

  6. If drugs are used for anesthesia, analgesia, euthanasia, or any other purpose, is the drug and dosage appropriate for those animals?

  7. If necessary, are humane endpoints in place?

Step 2: Finding Databases and Grey Literature Resources

Your search will only find relevant results if you search resources that contain your research topic. Bibliographic databases specialize in journal coverage, subject areas, types of materials, and publication years. Knowing where to search is just as important as knowing how to construct a search strategy.

Finding Databases to Search

The databases you choose will depend on the topic areas you are searching. AWIC provides a list of  bibliographic databases below covering information on biomedical research, biological science, animal science, veterinary medicine, animal use alternatives, toxicology and more! To learn which databases are available to you, visit your institution’s library website or contact your institution’s librarians to help identify databases and literature search training opportunities.

Bibliographic Databases

Note: This list does not include the only databases that can be searched. Mention of commercial enterprises or brand names does not constitute endorsement or imply preference by the U.S. Department of Agriculture. 

AGRICOLA

USDA. Agricultural Research Service. National Agricultural Library (NAL).

AGRICOLA is the NAL catalog of agricultural and applied sciences from plants to animals to soil and crops. It holds one of the largest collections of veterinary and animal science information.

Years of coverage: 1970 - present
Subjects coverage: all aspects of agriculture and allied disciplines, including animal and veterinary sciences, animal use alternatives, entomology, plant sciences, forestry, aquaculture and fisheries, farming and farming systems, agricultural economics, extension and education, food and human nutrition, and earth and environmental sciences.
Content types: journal articles; bibliographies; monographs; symposia; meeting abstracts; conference proceedings; monographs in series; textbooks; newsletters; book chapters; technical reports; published theses; dissertations; reviews; patents; annual reports; guides; translated journals; teaching guides; curriculum materials; lesson plans; pamphlets; formularies; press releases; letters; editorials; research projects
Access: free online and by vendor


AGRIS

Food and Agriculture Organization of the United Nations (FAO).

AGRIS is a global public domain database with over 4 million bibliographical records on agricultural science and technology.

Years of coverage: 1975 - present
Content types: journal articles; unpublished scientific and technical reports; theses; conference papers; government publications
Access: free online


ALTBIB: Alternatives to Animal Testing

DHHS. National Toxicology Program.

This bibliography helps identify methods and procedures for the development, testing, application, and validation of alternatives to the use of vertebrates in biomedical research and toxicology testing. Contents are a subset of MEDLINE records.

Years of coverage: 1980 - present
Subjects coverage: animal use alternatives
Content types: journal articles
Access: free online


BIOSIS Previews

Thompson Reuters.

This database has information from more than 6,000 national and international journals, serials, and proceedings.

Years of coverage: 1926 - present
Subjects coverage: all aspects of the life sciences, including animal use alternatives, veterinary medicine, biomedicine, biochemistry, pharmacology, genetics, agriculture, biotechnology, botany, ecology, and environmental science 
Content types: books; monographs; conferences; symposia; meetings; journal articles; patents
Access: fee based


CAB Abstracts

CABI.

This international database has over 10.4 million records of the world's applied life sciences literature.

Years of coverage: 1972 - present
Subjects coverage: agriculture, forestry, human nutrition, the environment, animal science, animal health, animal production, veterinary medicine, molecular biology, genetics, biotechnology, breeding, taxonomy, and physiology.
Content types: scientific journals; books; monographs in series; textbooks; technical reports; published theses; symposia; conference proceedings; review journals; selected patents; annual reports; bibliographies and guides; and translated journals
Access: fee based


Current Research Information System (CRIS)

USDA. National Institute of Food and Agriculture.

Search the U.S. Department of Agriculture's (USDA) documentation and reporting system of ongoing and recently completed agricultural, food and nutrition, and forestry research. Projects are conducted or sponsored by USDA research agencies, state agricultural experiment stations, the state land-grant university system, other cooperating state institutions, and participants of USDA-administered grant programs.

Content types: reports
Access: free online


EMBASE

Elsevier.

This is a comprehensive international database on pharmacological and biomedical literature, similar to Medline. 

Years of coverage: 1947 - present
Subjects coverage: biomedical research
Content types: journal articles; conference proceedings; symposia; meetings; books
Access: fee based


PubMed/MEDLINE

DHHSNIH. National Library of Medicine.

PubMed has millions of references, primarily from MEDLINE.

Years of coverage: 1948 - present
Subjects coverage: biomedicine and health, including portions of the life sciences, behavioral sciences, chemical sciences, bioengineering as well as animal use alternatives 
Content types: journal articles; some online books
Access: free online and by vendor


Scopus

Elsevier.

Scopus is an abstract and citation database covering over 240 disciplines. 

Years of coverage: 1823 - present
Subjects coverage: social sciences, life sciences, and health sciences, including agriculture, animal use alternatives, biomedical research, and animal and veterinary science
Content types:  journal articles; trade publications; books
Access: fee based


Web of Science

Clarivate Analytics.

Web of Science is an international, multidisciplinary database that also provides access to citation databases including Science Citation Index® (SCI®). Cited reference searching allows you to track prior research, see who is citing your work, and follow new developments.

Years of coverage: 1900 - present
Subjects coverage: agriculture, biological sciences, animal use alternatives, medical and life sciences, engineering, physical and chemical sciences, anthropology, law, library sciences, and the humanities.
Content types:  journal articles; review papers; meeting abstracts; letters; editorials; conference proceedings
Access: fee based

Why Search Multiple Databases

Searching multiple databases provides the best results for your search because no one database is comprehensive enough to capture 100% of the information on a given topic. Not all databases cover the same topic areas or contain citations from the same sources. Therefore, it’s crucial to search more than one database to capture all relevant material. View the example below:

Image
A Venn Diagram illustrating how many articles on immunology and chickens are found in Zoological Record, Biological Abstracts, and BIOSIS Citation Index.

The diagram above illustrates the results of a search on Immunology AND Chickens. If you were only to search one database, Zoological Records for example,  you would have only received 12 of the ~1,400 citations available on these topics.

Finding Grey Literature 3Rs Resources

Bibliographic databases (Scopus, AGRICOLA, PubMed, etc.) are not the only way to find 3Rs information. Grey literature can also be a resource for 3Rs methods and technologies. Grey literature refers to any literature that has not been published through traditional/commercial publications such as theses/dissertations, conference abstracts, reports, or newsletters. AWIC provides a list of 3Rs organizations that publish grey literature on their website. 

Step 3-4: Developing a Search String

Developing a search string includes the combination of words/phrases (keywords) and the search syntax/logic that brings them together (e.g., Boolean Operators, quotation marks, parentheses, etc.).

These components are the cornerstone of any effective search because they lay the foundation for your results. Your search string will determine how relevant the results are to your topic.

Finding Your Keywords

Keywords (or “search terms”) are words and phrases used to express the main concepts and ideas you are searching for. As you are determining the main concepts for your search, be sure to include scientific keywords (e.g., metabolism, immunology, gene expression, etc.) as well as 3Rs keywords (e.g., animal welfare, animal use alternatives, 3Rs alternatives, etc.) relevant to your research. Also, include synonyms and spell out any acronyms/abbreviations (e.g., AWIC or “Animal Welfare Information Center”).

 Example:

 You are searching for environmental enrichment for hamsters—

 Some of your keywords are: “Environmental enrichment” and hamster.

 Additional synonymous keywords could include:

Hamster: hamster OR hamsters OR cricetinae OR <insert specific breed>

 Environmental enrichment: "environmental enrichment" OR “enriched housing” OR “nesting material” OR bedding OR cardboard OR tube OR wheel OR toy

The keywords you choose are important because they serve as the bridge between what you search and the content within the databases you are searching. The keywords you choose also help to determine the results you will get from your search. Adding synonyms and/or related terms to your search string is also crucial because authors don’t always use the same keywords, spellings, or phrases to refer to the same topic. For example, anesthesia and anaesthesia are the same word, but spelled differently. Another example would be if one author uses ‘cattle’ throughout his/her paper, whereas another author might solely use the term ‘dairy cow(s)’ or ‘bovine’, etc.

Where can you find synonymous or related terms for your keywords?

  • Within your protocol
  • AWIC's Examples of 3Rs Keywords
  • Animal Welfare Information Center webpages
  • National Agricultural Library Thesaurus
    • Try searching for "animal use alternatives" in the search box and explore the hierarchy of terms. Look through the list of "entry terms" to find related terms or synonyms.
  • 3Rs Organization websites 
  • PubMed's MeSH thesaurus 
    • Type a term or phrase into the search bar (e.g. animal use alternatives). Look through the list of "entry terms" to find related terms or synonyms that you can include when you’re searching in other databases. Note that there might not be a MeSH term for all of your terms and phrases.
  • Papers published on the topic or related topics
  • Wikipedia articles
    • For example, if your protocol involves the gastrointestinal tract, searching “gastrointestinal tract” in Wikipedia will give you an overview of the parts and functions of this body system which could help you identify synonyms and keywords.
  • A simple Google search on the topic(s)
Examples of 3Rs Keywords

Many people make the mistake of putting the term “alternatives” or "3Rs" in the strategy and expect to find “all” possible alternatives. Because alternatives is a complex concept involving refinement, reduction and replacement, the use of  “alternatives” as a search term is best used only in those areas of study where larger amounts of research have been conducted on alternatives, such as in toxicology or education. In other areas of research the term “alternatives” often retrieves results not related to the 3Rs. It's best to use examples of the 3Rs to find relevant search results. 

The terms as listed below are not comprehensive and should not all be included in a search for a given protocol. They are provided to spark ideas for potential refinement, reduction and replacement keywords and concepts that can be used to conduct literature searches for research and alternatives.

Terminology for Replacement Alternatives

  • Animal replacement, alternatives to animal testing, animal use alternatives, new approach methodologies (NAMs)
  • Non-animal model
  • Animal-free antibodies
  • Cadaver, carcass
  • Cell culture, cell line, cell assay
  • Computer aided instruction, computer assisted instruction
  • Computer (simulation or application)
  • Computational (method or model)
  • Digital imaging
  • In silico
  • In chemico
  • In vitro
  • Isolated (cell, tissue, organ)
  • Mannequin, manikin
  • Mathematical (biology or model or simulation)
  • Organ-on-a-chip, microfluidic device, microphysiological system
  • Organoid
  • Plastinate, plastination
  • Simulation, simulator, trainer
  • Software
  • Tissue culture, organ culture
  • Tissue engineering
  • Video (disc, display)
  • Virtual reality, augmented reality 
  • Zebrafish embryos

Terminology for Reduction Alternatives

  • Animal model 
  • Animal reduction, animal use alternatives, minimize, reduce
  • Animal study registries
  • Animal serves as its own control
  • Biomarker, biological marker
  • Computational (method or model), in silico
  • Data repositories, reuse data, data reuse
  • Experimental design, statistical design
  • Imaging, scanning (magnetic resonance imagery, positron emission tomography, bioluminescent scanning)
  • Microsampling
  • Monitoring device, telemetry
  • reusing, sharing, repurposing animals
  • Sample size, number of animals
  • Tissue banks, antibody banks

Terminology for Refinement Alternatives

  • Analgesic, analgesia, pain management
  • Anesthesia, anaethesia, anesthetic, anaesthetic 
  • Animal welfare, well-being, wellness, humane, colony management, animal care
  • Bedding, substrate, nesting material, nestlets
  • Behavior, behaviour, ethology
  • Blood draw, blood sampling, blood collection, venipuncture
  • Challenge method, inoculate, infection, administer
  • Environmental enrichment
  • Euthanasia, humane endpoint
  • Grimace scales, pain monitoring
  • Handling, tunnel handling, cup handling, restraint, rat tickling
  • Husbandry, housing, caging
  • Injection, phlebotomy
  • Noninvasive, less invasive, minimally invasive, non aversive, painless, low stress, stress-free
  • Positive reinforcement training, animal training
  • Refinement
  • Social housing, group housing, pair housing
  • Telemetry device, biotelemetry 

Search Logic & Syntax Tools

When searching, the keywords and synonyms you choose to express the main concepts are combined using search logic (AND, OR, NOT) and syntax tools (truncation, quotation marks, etc.) to help you find the most relevant results. In-depth explanations of search logic and syntax tools are provided below.

  • Boolean Operators - Use words such as AND, OR, NOT to expand or narrow a search.
    • AND finds information containing both terms, which narrows the search (Ex: (pig OR pigs OR porcine OR swine) AND ("immune response"))
    • OR finds information containing either one or both terms, which expands the search (Ex: (pig OR pigs OR porcine OR swine))
    • NOT finds information that does not contain a term, which narrows the search (Ex: (pig OR pigs OR porcine OR swine) NOT (guinea))
  • Parentheses - Used to combine synonymous terms within a search string and to encompass the search string itself.

Ex: (dog OR dogs OR canine) AND (pain OR discomfort OR distress)

  • Truncation - A symbol added to the end of the root of a word to search for all forms of a word (commonly an asterisk (*)).

Ex: behav*= behavior, behaviour, behaves, behave, behaving, behaved, etc.

**NOTE: Truncate words carefully. Beware of unintended results! Unwanted keywords can be eliminated using the Boolean Operator, NOT. 

Ex: buck* = buck, bucks, bucket, buckling, buckwheat, etc. 

  • Quotation Marks - Search for phrases using double quotation marks (i.e., "pair housing "). If double quotations are not used, words are automatically searched individually using the Boolean operator AND in many databases. Note that it is important to use straight quotation marks (i.e. " ") rather than curly quotation marks (i.e. “ ”) because your results can be effected in some databases. Learn how to change quotes settings for Microsoft Word

Ex (with double quotation marks): "animal welfare" OR "environmental enrichment"

Ex (without double quotation marks): animal AND welfare OR environmental AND enrichment

  • Proximity operators - Searches for one word or phrase within a certain distance of another word or phrase. Common proximity operators used are: N, Near/ or W/.  When using this tool, the words or phrases being searched can be found in any order within the search results (see example below).

 Ex: blood NEAR/3 collect* = blood collection, collection of arterial blood, collecting blood

*Notice the example search retrieves citations with phrases that have the terms ‘blood’ and ‘collect*’ presenting in various orders.

**NOTE: Proximity operators vary across databases, so check the ‘HELP’ section of the database you are searching or AWIC's database search operator reference guide for help). Some databases, such as PubMed, do not use proximity operators.

Creating a Search String

A well-constructed search string incorporates a combination of keywords, their synonyms, and search syntax (Boolean operators, parenthesis, truncation, etc.). When breaking down a protocol, use multiple search strings to individually encompass each targeted question you are asking.

Search String Example: 

(recover* OR assess* OR collect* OR analy* OR process* OR sampl* OR measur*) NEAR/5 (tissue* OR “tissue sample*” OR fluid* OR “fluid sample*” OR “blood sample*” OR “urine sample*”)

Step 5: Modifying a Search String

Modifying a Search String

Searching is a trial-and-error process. Search results are usually ranked by relevancy so assessing the first 100 or less results can give you a general feel if your search is on the right track. If you find that your original search string is bringing back a lot of irrelevant information, it might be time to modify your search string. Search strings may be modified in multiple ways and in multiple steps to get the most relevant results. Here are some quick ways to modify a search string:

  • Change the field you are searching in 
    • Ex: Limit the search field from title/abstract to just title 
  • Limit by Publication Year to decrease the number of citations you are receiving
    • Use with caution—applying this feature might cause you to exclude relevant information
  • Remove irrelevant search terms with a NOT statement
    • Ex: pig NOT guinea
  • Narrow the search by replacing general terms for terms specific to that disease, method, procedure, etc.
    • Ex: use Babesia, which is more specific than parasite

What indicators can you look for to help you know if you need to broaden or narrow your search string?

Indicators that you should broaden your search string:

  • You are getting 0 or very few results.
  • Your results are too specific.
  • The citations don’t involve the concepts you are looking for.

Indicators that you should narrow your search string:

  • Many of the citations are irrelevant.
  • The search string brings back an overwhelming number of results. Here are some ways to narrow your search:
    • Change the fields you’re searching (e.g., limit from title/abstract to just the title).
    • Limit by date (e.g., past 5 - 10 years).
    • Limit by language (e.g., only articles in English).
    • Sort the results by the highest-cited articles (keep in mind that newer articles won’t have been cited as much as older articles).
    • Limit by article type (review or systematic review articles usually give a more comprehensive overview of a topic).
    • Modify the search string. For example, if you did a search for gastrointestinal tract and really want to focus on the colon,  replace gastrointestinal tract terms with more specific terms for colon. 
    • Add another search concept. For example, if you did a search for elephant behavior, but only want information when they are housed in zoos, add terms for zoos to your search string. 

General Comments:

Remember: Protocols should be evaluated individually because no one search will be identical. Therefore, each time you write a new protocol for a study/experiment, a new alternatives literature search should be conducted. Also, remember that a perfect search strategy to retrieve every citation regarding reduction, refinement, and replacement does not exist. Many factors affect the literature search outcome—including, but not limited to, the databases used in the search, area of research, the species involved, procedures used, chemicals tested, experimental design, etc.

Step 6: Records and Citation Management

Keep a record of your keywords, search strings, databases searched, and publication years searched. This allows you to simply update your search when needed in the future, rather than regenerating a list of keywords and building new search strings every time.

You can also use citation management software (CMS) such as EndNote or Zotero to store, organize and utilize the relevant citations you find. CMS helps with generating reference lists, bibliographies, and footnotes. Contact your institution’s librarian to find out which citation managers are available to you. If you are a United States Department of Agriculture (USDA) employee and need assistance with using CMS, contact the National Agricultural Library.

3Rs Literature Search Examples

Additional Resources

Publication Guidelines

  • ARRIVE Guidelines

    National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs).

    "The ARRIVE guidelines (Animal Research: Reporting of In Vivo Experiments) are a checklist of recommendations to improve the reporting of research involving animals – maximizing the quality and reliability of published research, and enabling others to better scrutinize, evaluate and reproduce it."

  • Guidance for the Description of Animal Research in Scientific Publications

    Institute for Laboratory Animal Research (ILAR). Division on Earth and Life Studies. National Research Council. 

    This report "outlines the information that should be included in scientific papers regarding the animal studies to ensure that the study can be replicated. It urges journal editors to actively promote effective and ethical research by encouraging the provision of sufficient information."  

  • Gold Standard Publication Checklist for Animal Studies

    Central Animal Laboratory and 3R Research Centre.

    Systematic reviews "are not yet widely used nor undertaken in the field of animal experimentation, even though there is a lot to be gained from the process. Therefore, a gold standard publication checklist (GSPC) for animal studies is presented in this paper."

  • Improving Animal Research Reporting Standards (PDF | 194 KB)

    International Council for Laboratory Animal Science (ICLAS).

    ICLAS wrote this article "to harmonize animal research reporting guidelines to encourage improvements in the quality of science where laboratory animals are involved."

Frequently Asked Questions

What are search hedges? Are there 3Rs alternatives search hedges available?

Search hedges are pre-made, standardized search strings that can be used to identify relevant articles for a specific research topic or population. They can save time and ensure all relevant keywords, related terms, and synonyms are included. AWIC is currently building search hedges for 3Rs alternatives and common research animal species. AWIC plans to make them publicly available in 2022, so check back with us!

How/when do I know my alternatives literature search is comprehensive enough or when do I stop searching for 3Rs alternatives?

Literature searching is a trial-and-error process. If you have searched multiple databases (≥ 3), used multiple search strings, and included multiple keywords, related terms and synonymous terms within your search strings, then typically you can consider your alternatives literature search to be comprehensive enough, especially if you are finding relevant alternatives. Sometimes there are no current alternatives to a procedure, method, or technique so you may not find any literature.

As an Institutional Animal Care and Use Committee (IACUC) member, what red flags can I look for to know if a principal investigator’s alternatives literature search isn’t adequate?

To evaluate a principal investigator’s alternatives literature search, keep these red flags in mind:

  • Only 1 database was searched.
  • Only included terms related to the painful procedures without including any relevant 3Rs alternatives terms.
  • Only used the terms “alternatives”, “replacement", “refinement", and/or “reduction” without any other 3Rs alternatives terms specifically related to the protocol and/or procedure. Other 3Rs terms might include non-invasive (refinement), experimental design (reduction), or cell line (replacement).
  • Did not use multiple keywords/synonymous terms or multiple search strings within their search.
  • Keywords used are not relevant to the protocol.
  • Search syntax and tools were not used at all or not used correctly (e.g. wrong Boolean operators or incorrect placement in the search string, lack of quotation marks or parentheses).
  • Search did not cover an adequate time period (10-15 years).
I can’t find any relevant 3Rs alternatives information. Who can help me with my alternatives literature search?

Your institution’s librarians can help you with your alternatives literature search. Although they may not be subject matter experts, they are experts at finding information. You can also contact AWIC at awic@usda.gov. AWIC conducts alternatives literature searches for free, as well as provides training/guidance that will help you conduct the literature search yourself. If you wish to request an alternatives literature search, please fill out AWIC's request form.

Contact Us

If you have questions or need additional help literature searching, please contact AWIC at awic@usda.gov

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