Background: Equine grass sickness (EGS), also known as equine dysautonomia, is a commonly fatal disease of grazing horses. It has been reported predominantly in Northern Europe and South America, and the UK has the highest prevalence of the disease worldwide. It is a multisystemic neuropathy resulting in neuronal degeneration and loss, particularly from the autonomic and enteric nervous systems. The severity of clinical signs varies, but is proportional to the extent of neuronal damage. Due to the widespread and highly fatal nature of the disease, EGS has received much attention in the veterinary literature in recent years. Research has concentrated particularly on identifying the cause, improving antemortem diagnostic accuracy, prognostic indicators and the development and trial of a potential vaccine. Aim of the article: This article provides a clinical update on EGS, including recent advances in the identification of a causal agent, diagnostics, prognostic indicators and potential avenues for prophylaxis.