Equine grass sickness

Research output: Contribution to journalLiterature reviewpeer-review


Equine grass sickness (EGS; equine dysautonomia) is a polyneuronopathy affecting both the central and the peripheral nervous systems of horses. As the name implies, EGS almost exclusively affects grazing horses, resulting in the development of a characteristic array of clinical signs, most of which can be attributed to neuronal degeneration in the autonomic and enteric nervous systems. Varying disease severities occur, largely determined by the extent of neuronal degeneration in the myenteric and submucous plexuses of the enteric nervous system. Extensive neuronal degeneration, as seen in acute and subacute forms of EGS, results in intestinal dysmotility, the severity of which is incompatible with survival. In comparison, a proportion of chronic forms of EGS, characterised by less severe neuronal degeneration, will survive. Despite extensive research efforts since EGS was first reported over 100 years ago, the precise aetiology remains elusive. This article reviews much of the scientific literature on EGS, covering epidemiology, pathology, diagnosis, treatment and aetiological hypotheses.
Original languageEnglish
Pages (from-to)545-553
JournalEquine Veterinary Journal
Issue number5
Early online date28 Feb 2014
Publication statusE-pub ahead of print - 28 Feb 2014


  • horse
  • grass sickness
  • dysautonomia
  • Clostridium botulinum
  • Key-Gaskell
  • Fusarium


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