What is grass sickness?
Prof Chris Proudman FRCVS 28 June, 2006 Equine grass sickness (EGS) is a disease of the nerves that co-ordinate intestinal movement and peristalsis. More specifically, scientists think the disease is caused by toxins released from the bacteria Clostridium botulinum that damage these and other nerves throughout the horse’s body. The signs of disease shown by horses with EGS reflect this damage to the nervous system: • Damage to nerves of the intestine causes normal gut motility to cease. This leads to distension of small intestine and impaction of large intestine with food material. • Nerve damage and release of adrenalin-like substances causes an increase in heart rate. • Damage to nerves that cause sweating causes intermittent “patchy” sweating, often on the neck and flanks. • Damage to the nerves controlling saliva production can cause profuse salivation. Grass sickness occurs in two different forms. The sudden-onset (acute) form of the disease is characterised by signs of colic. In
