title: Severe hyponatraemia in foals: clinical findings, primary diagnosis and outcome.
abstract: OBJECTIVE
  To evaluate severe hyponatraemia in foals presenting as medical emergencies to an intensive care unit (ICU) in order to determine the prevalence, clinical findings, primary diagnosis and outcome.
  
  
  METHODS
  Retrospective case study of records from Thoroughbred foals aged less than 3 months presenting to an ICU as medical emergencies in 2002-12; foals with severe hyponatraemia (serum sodium <122 mmol/L) on admission laboratory data were identified. Data retrieved included signalment, clinical findings, laboratory results, primary diagnosis, treatment and outcome.
  
  
  RESULTS
  Severe hyponatraemia was identified in 69/1718 Thoroughbred foals (4%) presenting to the ICU during the study period. Of the 69 foals, 11 (15.9%) presented with neurological signs attributable to hyponatraemic encephalopathy and 7 of these foals had seizures; other neurological signs included obtundation, ataxia and apparent blindness. The three most common primary diagnoses of the 69 foals with severe hyponatraemia were renal disease (18/69, 26.1%), enterocolitis (16/69, 23.2%) and uroperitoneum (15/69, 21.7%). Treatment was directed at the primary disease and correction of the hyponatraemia. A total of 50 of the 69 foals (72.5%) with severe hyponatraemia survived to hospital discharge and 38 of them (76%) survived at least 12 months following discharge.
  
  
  CONCLUSIONS
  The prevalence of severe hyponatraemia in this study population was 4%. The majority of foals with severe hyponatraemia did not demonstrate direct clinical manifestations as a result of the low serum sodium concentration. The outcome of foals with severe hyponatraemia was mostly favourable.
authors.affiliation: Clovelly Intensive Care Unit, Scone Equine Hospital, 106 Liverpool Street, Scone, New South Wales 2337, Australia. Niamh.Collins@sconeequine.com.au.
authors.forename: N M
authors.initials: NM
authors.lastname: Collins
authors.affiliation: Clovelly Intensive Care Unit, Scone Equine Hospital, 106 Liverpool Street, Scone, New South Wales 2337, Australia.
authors.forename: J E
authors.initials: JE
authors.lastname: Axon
authors.affiliation: Equine Specialist Consulting, Scone, NSW, Australia.
authors.forename: J B
authors.initials: JB
authors.lastname: Carrick
authors.affiliation: Clovelly Intensive Care Unit, Scone Equine Hospital, 106 Liverpool Street, Scone, New South Wales 2337, Australia.
authors.forename: C M
authors.initials: CM
authors.lastname: Russell
authors.affiliation: Connelly Intensive Care Unit, University of Pennsylvania, New Bolton Center, PA, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Palmer
mesh_terms: D000208:Acute Disease; D000818:Animals; D001927:Brain Diseases / Q000209:etiology / Q000662:veterinary; D005260:Female; D006734:Horse Diseases / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy; D006736:Horses; D007010:Hyponatremia / Q000175:diagnosis / Q000473:pathology / Q000628:therapy / Q000662:veterinary*; D008297:Male; D012189:Retrospective Studies; D016896:Treatment Outcome
keywords: critical care; foals; hyponatraemia; hyponatraemic encephalopathy