Analgesic use, safety and pharmacokinetics of acetaminophen in equids: A structured scoping review

Despite its frequent use in equine clinical practice, scientific data on the use of acetaminophen in horses remain limited.

To map and critically appraise the available evidence on the analgesic use, safety and pharmacokinetics of acetaminophen in horses.

Structured scoping review.

A comprehensive search was performed in accordance with the PRISMA Extension for Scoping Reviews using the terms '(paracetamol OR acetaminophen) AND (pain OR safety OR toxicosis OR pharmacokinetics) AND (horse OR pony OR donkey OR mule)' across Web of Science, Scopus, and PubMed from database inception to 27 July 2025. Experimental and clinical studies, reviews and case reports evaluating acetaminophen in equids were eligible. Publications without acetaminophen information about analgesia, safety or pharmacokinetics in horses were excluded. Each article was screened and charted according to study design, level of evidence (LoE) (methodological robustness) and thematic domain by two evaluators.

Of the initial 45 articles, 27 met eligibility criteria. Ten studies were classified as LoE 1, six as LoE 2, seven as LoE 3, and four as LoE 5. Based on study design and thematic domain, the included publications comprised four categorised as 'case reports', seven as 'narrative reviews', one as 'prospective comparative studies', 11 as 'pharmacokinetics', and four as 'pharmacokinetics and concentration-effect relationship'.

Limited number of clinical studies and heterogeneity of available evidence.

This review highlights the growing but still limited evidence on acetaminophen use in horses. While pharmacokinetic data are robust, clinical trials remain scarce and underpowered. Acetaminophen appears promising as part of multimodal analgesia, yet its efficacy as a sole agent and long-term safety require further investigation before widespread clinical adoption.