Synthesised evidence

Evidence syntheses are designed to support clinical decision-making by summarising the available evidence on a clinical topic following a formal search and appraisal of the primary research by a qualified third party.

These can save the practitioner a huge amount of time and effort as the work has already been done for you (though you should check that the information is up-to-date, and that the methodology described seems sound).

For busy practitioners, a quick search of synthesised evidence should be the first port of call. If there is a high quality, up-to-date synthesis of evidence already published, there may be no need to do your own detailed searches.

With an ever-increasing number of publications in the veterinary sciences, it is challenging if not impossible for busy clinicians to keep up with the literature. Reviews summarising the outcomes of various studies are therefore a very efficient method for obtaining the clinical “bottom line” about what works well and what doesn’t. ‘There are different types of evidence synthesis; the three main types referred to in this tutorial are evidence summaries, systematic reviews with or without meta-analyses, and practice guidelines.


Most GPs in human medicine actually use systematic reviews and evidence summaries and guidelines to answer their clinical questions, and don’t do many searches of the primary literature themselves, if any. For example, in the UK they may rely on Nice Evidence Search

Evidence syntheses are an area of new development for the veterinary profession, and we expect these ‘secondary evidence sources’ to grow and expand as EBVM takes off, but some of the best sources for now are:

Online collections of evidence summaries

  • Veterinary Evidence RCVS Knowledge, the charity partner of the Royal College of Veterinary Surgeons (RCVS) in the UK, makes resources available via its open access online portal, including a collection of Knowledge Summaries.
  • BestBETs for Vets The Centre for Evidence-based Veterinary Medicine at Nottingham University, UK offers a freely accessible database of Best Evidence Topics (BETS).
  • Banfield Applied Research and Knowledge (BARK) In the USA, the research division of Banfield, one of the largest privately owned practices, is actively generating information to support EBVM by conducting population-based research on the medical records from their animal hospitals. BARK data is shared in different formats, including Critically Appraised Topics (CATs) and journal articles.
  • Equine Veterinary Journal: Clinical Evidence in Equine Practice online collection lists systematic reviews and critically appraised topics.
  • Zoonoses and Public Health Special issue: systematic reviews and meta-analysis in animal agriculture and veterinary medicine.

Evidence summaries published in journals

Some veterinary journals now feature regular evidence summaries. Examples include:

  • Veterinary Record: Clinical Decision-Making Starting in April 2015 the Veterinary Record has started a new section called Clinical Decision-Making which will include evidence syntheses such as BestBETs and CATs.
  • The quarterly Banfield Journal includes practical clinical articles on the diagnosis and treatment of medical conditions, plus an evidence-based veterinary medicine feature to enhance practitioners’ clinical decision-making.

Systematic Reviews

Systematic reviews are considered the “gold standard” of evidence. If you can find a recent systematic review that answers your specific question this will be a great help, as someone else has already spent the time doing the appraisal work for you.


The Cochrane Collaboration and the Cochrane Database of Systematic Reviews provide the gold standard for high quality systematic reviews in human medicine, and there is now a will in the veterinary community to try and build something comparable. In these early days of EBVM, a direct comparator of Cochrane does not exist for veterinary medicine, but the VetSRev database (see below) has been up and running since 2013.
  • The VetSRev database is a freely accessible online database of citations for systematic reviews relevant to veterinary medicine and science. Produced by the Centre for Evidence-based Veterinary Medicine at the University of Nottingham, UK, it aims to disseminate information about existing systematic reviews to the veterinary community. You may be surprised by the number that already exist, and the number published each year is growing exponentially, so the coverage should get better all the time.
Identifying systematic reviews via the CAB abstracts literature database
The publisher of the CAB Abstracts database also offers the following advice for identifying systematic reviews via CAB abstracts: “The “Evidence based research” facet is now available under Refine Results and is designed to filter your search results to systematic reviews and meta-analyses. Apply this filter after you search to view only results drawn from evidence based literature”. (CABI web pages, 2015)

Practice guidelines

The evidence-based approach can be used to create practical clinical guidelines – systematically developed statements that assist practitioners with clinical decision-making on a specific topic. Veterinary practices can adopt the EBVM methodology to produce their own guidelines. An EBVM approach can help improve the quality and thus the efficiency and effectiveness of a veterinary practice. Some examples include:

  • Practice guidelines for treatment of canine atopic dermatitis by De Boer (2013), which he presented at the 1st International EBVM Network conference.
  • The RECOVER guidelines on veterinary CPR, the first evidence-based recommendations to resuscitate dogs and cats in cardiac arrest, produced by the American College of Veterinary Emergency and Critical Care and the Veterinary Emergency and Critical Care Society.