Equine grass sickness is a devastating neurological disease of grazing horses with very high mortality. Understanding risk factors informs prevention where possible.
Equine grass sickness causes some of the most severe and rapid welfare deterioration in equine medicine. The complete failure of gut motility creates overwhelming discomfort as ileus develops; dysphagia prevents swallowing; and the autonomic dysfunction produces patches of sweating and muscle tremors that indicate profound physiological distress. Acute and subacute cases deteriorate rapidly to a point where humane euthanasia is overwhelmingly indicated on welfare grounds. The decision to euthanize should be made promptly when prognosis is hopeless rather than prolonging suffering through continued treatment. For chronic cases, the intensive nursing care required — multiple daily feedings, specialist nutritional management, physiotherapy — represents a significant burden on horse and owner, and quality of life assessment must be ongoing throughout the recovery process.