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An acute outbreak of equine dysautonomia (equine grass sickness) in a group of eight Przewalski's horses (Equus ferus [caballus] przewalskii)

Girling, S. J.; Fraser, M. A.; Richardson, D.; Harley, J.; Ireland, J. L.; Naylor, A.; Milne, E.


S. J. Girling

M. A. Fraser

D. Richardson

J. Harley

J. L. Ireland

A. Naylor

E. Milne


Equine grass sickness (EGS) is a neurodegenerative disease affecting grazing equids of which a single case of the chronic clinical presentation has previously been reported in a Przewalski's horse (Equus ferus [caballus] przewalskii). A group of 8 Przewalski's horses were moved to a new enclosure, recently vacated by a group of 4 Eastern kiang (Equus kiang holdereri) that showed no evidence of disease. After 23 days the first Przewalski's horse showed clinical signs of acute EGS including flank sweating, belly kicking, rapid loss of body condition, cessation of faecal passage, nasogastric reflux and mouthing water. It was subjected to euthanasia within 48 h due to lack of therapeutic response. Within 24 h of this first case developing clinical signs, a further 5 Przewalski's horses showed similar clinical signs of acute EGS and were subjected to euthanasia. Post mortem examinations confirmed acute EGS, with all animals demonstrating typical chromatolysis, cytoplasmic hypereosinophilia, cellular swelling, vacuolation, pyknosis and loss of nuclei in approximately 90% of neurones in the cranial cervical and cranial mesenteric ganglia and myenteric and submucosal plexi of the ileum. Two Przewalski's horses within the group showed no clinical signs of disease. No single pathogen was identified as the causal agent, but the epidemiological pattern of the outbreak was typical for that previously reported for acute EGS in domestic equids. All affected animals and the 2 surviving Przewalski's horses had low antibody titres to Clostridium botulinum type C. This is the first report of acute EGS in a herd of Przewalski's horses.

Journal Article Type Article
Acceptance Date Oct 29, 2015
Online Publication Date Oct 29, 2015
Publication Date 2017-07
Deposit Date Jan 5, 2016
Journal Equine Veterinary Education
Print ISSN 0957-7734
Electronic ISSN 2042-3292
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 29
Issue 7
Pages 358-361
Keywords Equine
Public URL
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