Nausea: Current knowledge of mechanisms, measurement and clinical impact

- Mechanisms of nausea are complex and, unlike emesis, are not well defined.
- Methods of nausea measurement are subjective, liable to inter observer variability.
- Nausea is difficult to quantify in the veterinary clinic due to its subjective nature.
- Biomarkers would aid in more objective assessment of nausea.
- Anti-emetic treatments are less efficacious for the treatment of nausea than emesis.

Nausea is a subjective sensation, which often acts as a signal that emesis is imminent. It is a widespread problem that occurs as a clinical sign of disease or as an adverse effect of a drug therapy or surgical procedure. The mechanisms of nausea are complex and the neural pathways are currently poorly understood. This review summarises the current knowledge of nausea mechanisms, the available animal models for nausea research and the anti-nausea properties of commercially available anti-emetic drugs. The review also presents subjective assessment and scoring of nausea. A better understanding of the underlying mechanisms of nausea might reveal potential clinically useful biomarkers for objective measurement of nausea in species of veterinary interest.