Literature Searching: How to Find Animal Use Alternatives

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 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.

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.

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:

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. 

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)

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 - Use to combine synonymous terms within a search string and to enclose 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*”)

Running a Search String

After you create your search string, enter it into the databases you selected in step 2. This will provide you with an initial set of results to review. Search results are usually ranked by relevancy so assessing the first 100 or less citations can give you a good idea if your search is on the right track or not. If most of the results are relevant, then your search is complete. However, most search strings need some modifications to return the most relevant citations. Ways to modify a search string are discussed in the next step. 

Search Hedges

In addition to generating your own keywords and search strings, you can use search hedges if they are available. Search hedges are pre-made, standardized search strings that can be used to identify relevant articles for a specific research topic. They can save time and ensure all relevant keywords, related terms, and synonyms are included. 

AWIC developed search hedges for various laboratory animal species as well as other 3Rs topics. AWIC plans to post hedges for 3Rs alternatives methods such as environmental enrichments, social housing, abnormal behavior, and other topics in 2024. 

Modifying a Search String

Searching is a trial-and-error process. 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.

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.

Search hedges are pre-made, standardized search strings that can be used to identify relevant articles for a specific research topic or population. The hedges below can be downloaded and used for free.

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