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Animal Alternatives Searching

This guide was designed to aid researchers completing literature searches for animal alternatives as part of the protocol submission and review of NYU's University Animal Welfare Committee (UAWC).

The Research Question

Most searches benefit from defining a question prior to developing a search strategy. Typical questions asked in a search for alternatives may be:

  • what has already been done in this area? 
  • what models have been used? Are better models available?
  • what are the best methods/procedures?
  • alternative consideration for potential pain and distress?

A more specific question may be something like: 

Are there less painful or distressful alternatives to the procedures being employed in the research on the effects of L-fucose or arachidonic acid in the establishment of acute (trauma-induced) osteomyelitis caused by S. aureus in rats?

Defining the question(s) precisely can help you to begin identifying keywords and synonyms.

Structuring a Search

Boolean Operators

Venn diagrams demonstrating use of AND, OR, and NOT.

Note: most databases and search engines assume AND if no operator is used between terms.


To find results containing all terms or concepts. Narrows results. primates AND enrichment


To find results containing any of the terms. Used for combining synonyms or similar concepts. Broadens results. mouse OR murine OR mus musculus


Used to exclude a term from all results. Narrows results, but can often exclude relevant articles. Use with caution. animal models NOT primates

Use parentheses to link sets of similar concepts or synonyms:

(eye OR ocular OR cornea) AND toxicity testing AND (alternatives OR biological assay OR in vitro OR ex vivo OR culture)


Can be used to include all forms of a word in a search without having to type each one out. For example, in PubMed:

  • therap*  will return results with therapy, therapies, therapeutic, therapeutics... etc.
  • reduc*   will return reduce, reduces, reduction... etc.

Most databases use the asterisk (*) for truncation, but not all. If you are unsure, you can usually find the appropriate symbol under Help.

Keywords & Subject Headings


  • When you search Google and often when you search databases, you are generally using keywords. A search engine or database will look for exact matches to your keywords in the content available (title, abstract, authors, subject headings, and, sometimes, full text). 
  • To be comprehensive, you need to think about what words authors might use to describe their own work and search ALL of them: mouse vs. mice vs. mus musculus; heart attack vs. myocardial infarction.
  • Using keywords is often the best choice if you are searching for very specific terms or terms that are new (a brand new technique, for example).

Subject Headings:

  • Subject headings are standardized terms assigned to articles in a database by indexing experts based on the article's content. They are standardized so that, no matter what synonyms authors used to describe their work in the title or abstract, a consistent term will always be assigned to articles that are about the same subject.
  • For example, in PubMed, there is a subject heading "Manikins", which returns articles that might otherwise only be found searching keywords like: mannequin, simulator, hands-on teaching aid, virtual educational technologies, SimMan 3G, simulated patient, HFHS, etc. In this case, searching keywords would result in many irrelevant results related to other simulation techniques and other topics, while potentially missing many relevant articles that did not happen to include the keywords searched.
  • Finding the appropriate subject headings in a database can help you to discover broader or narrower terms that may be helpful to improve your search. For example, a broader subject heading than "Mice" is "Murinae" and includes both mice and rats. There are also many narrower subject headings than "Mice" that represent inbred and mutant strains and knockouts.