Equine Grass Sickness (EGS) is often a fatal neurologic disease affecting primarily young grazing horses. It was first reported in Scotland and now has occurred in most of Northern European countries and in South America. Horses with the more severe forms of this disease experience colic, difficulty swallowing, reflux of stomach contents, excessive salivation, a high heart rate, impacted intestines, muscle tremors and patchy sweating. Horses with the less severe form experience sudden and extreme weight loss, drying of the nasal membranes and difficulty in swallowing. Only the mild cases receive intensive care survive.
However, the Veterinary Medicines Directorate has approved a pilot trial of a grass sickness vaccine where the University of Edinburgh will include 100 horses and ponies, enrolled by their owners. This pilot study is in preparation for a full vaccine trial which is likely to start in 2013 or 2014 depending upon sufficient funding where 1,000 horses and ponies will be involved. It is hoped that these vaccine trials will mark a breakthrough in the prevention of this devastating disease.