Emesis in Rodents: Present or Absent? A Critical Review of the Evidence and Implications for the Use of Rodents in Biomedical Research
by
, and
Gustavo Alcantara De Sousa
1,
Masahiro Nemoto
2,
John A. Rudd
3,
Gareth J. Sanger
4 and
Paul L. R. Andrews
5,* 1
Faculty of Veterinary Medicine, Universidade Nove de Julho, Memorial Campus, São Paulo 01156-050, Brazil
2
Department of Pharmacology, Japanese Red Cross Hokkaido College of Nursing, Kitami 090-0011, Japan
3
School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
4
Blizard Institute, Faculty of Medicine and Dentistry, Queen Mary University of London, London E1 4NS, UK
5
Institute of Medical and Biomedical Education, City St George’s, University of London, Tooting Campus, London SW17 0RE, UK
*
Author to whom correspondence should be addressed.
Biology 2026, 15(1), 35; https://doi.org/10.3390/biology15010035
Submission received: 5 October 2025
/
Revised: 16 December 2025
/
Accepted: 17 December 2025
/
Published: 25 December 2025
Simple Summary
The ability to vomit is an important component of the body’s defensive systems to limit the effects of toxins ingested with food. However, in a notable exception amongst mammals, it is widely reported that rodents (e.g., rats and mice) and lagomorphs (e.g., rabbits) are unable to vomit. This review addresses the validity of this assumption in the light of both historical and recent evidence of behaviours that are apparently analogous to retching and/or vomiting in selected rodent species. The evidence is critically evaluated based on a detailed examination of anatomical, functional and experimental factors. We conclude that whilst there is some limited published evidence for retching, the ability to vomit is not proven. The reasons for this are discussed and include: (i) anatomical constraints in the region of the gastro-oesophageal junction which would impede the bulk ejection of gastric contents during vomiting (especially semi-solids); (ii) neural control of the diaphragm and lower oesophageal sphincter; (iii) possible differences between species with a well-defined vomiting response and those without, in the brainstem pathways coordinating the activity of the muscles involved in retching and vomiting. These conclusions need to be tested experimentally. The wider implications for rodent biology and evolution are discussed.
Abstract
Vomiting, a key defence against accidentally ingested toxins, is widely present in mammals. Notably, rodents (e.g., rats, mice) are generally assumed to be unable to vomit, as commonly reported over the last ~100 years, but they are used extensively for biological and particularly biomedical research. However, three recent mouse papers reported ‘emetic-like’ responses induced by substances that are emetics in humans. Therefore, we critically re-examined the literature underpinning this longstanding view, integrating the recent and largely overlooked historical evidence challenging this consensus. We reappraise the ability of rodents to retch and vomit, concluding that whilst there is some published evidence for retching, the ability to vomit is unproven and for a range of physiological and anatomical reasons (e.g., organisation of the gastroesophageal anti-reflux barrier), it would be problematic. Experimentally testable hypotheses to explain the conflicting findings are proposed, together with criteria that should be fulfilled to define a behaviour as retching or vomiting in rodents. A detailed comparison is made of the physiological and anatomical differences between rodents and species known to vomit. We consider the significance of our conclusions for biomedical research, particularly in relation to the digestive tract and central nervous system, and the wider implications for rodent biology.
Keywords:
digestive tract; emetic; oesophageal sphincter; mouse; nausea; rat; retching; rodent; vomiting
