title: Neurodegeneration in equine grass sickness is not attributable to niacin deficiency.
abstract: BACKGROUND
  The aetiology of equine grass sickness (EGS) is currently unknown. We hypothesised that an acute deficiency of niacin (vitamin B3), which plays a key role in neural homeostasis, may contribute to neurodegeneration in EGS. Niacin deficiency can potentially result from ingestion of niacin antagonists produced by pasture mycotoxigenic fungi.
  
  
  OBJECTIVE
  To compare the niacin status of EGS and control grazing horses. A secondary objective was to compare blood concentrations of vitamins B1, B2 and B6 in EGS and control grazing horses to determine if the status of these vitamins was altered in EGS.
  
  
  METHODS
  Case-control study.
  
  
  METHODS
  Indices of niacin status, namely the erythrocyte nicotinamide adenine dinucleotide:nicotinamide adenine dinucleotide phosphate ratio (NAD:NADP ratio) and erythrocyte concentrations of NAD and NADP, were compared in blood collected from EGS and healthy control grazing horses. Blood concentrations of vitamins B1, B2 and B6 were also compared.
  
  
  RESULTS
  There was no significant intergroup difference in the NAD:NADP ratio, the main index of functional niacin status (control group: median 2.1, interquartile range [IQR] 1.8-2.6; EGS group: median 2.1, IQR 1.9-2.6). EGS horses had significantly higher (median value increased by 25%) concentrations of NADP. There were no intergroup differences in blood concentrations of vitamins B1, B2 and B6.
  
  
  CONCLUSIONS
  The interpretation of data was limited by the lack of previously defined equine reference ranges for many of the analytes. Sample size was low.
  
  
  CONCLUSIONS
  Niacin deficiency does not contribute to EGS neurodegeneration.
authors.affiliation: Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, UK.
authors.forename: B C
authors.initials: BC
authors.lastname: McGorum
authors.affiliation: Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, UK.
authors.forename: R C
authors.initials: RC
authors.lastname: Jago
authors.affiliation: Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, UK.
authors.forename: E
authors.initials: E
authors.lastname: Cillan-Garcia
authors.affiliation: Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, UK.
authors.forename: R S
authors.initials: RS
authors.lastname: Pirie
authors.affiliation: Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, UK.
authors.forename: J A
authors.initials: JA
authors.lastname: Keen
authors.affiliation: Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, UK.
authors.forename: R J M
authors.initials: RJM
authors.lastname: Reardon
authors.affiliation: Biolab Medical Unit, London, UK.
authors.forename: P Y
authors.initials: PY
authors.lastname: Saffu
authors.affiliation: Biolab Medical Unit, London, UK.
authors.forename: N J
authors.initials: NJ
authors.lastname: Miller
mesh_terms: D000818:Animals; D001342:Autonomic Nervous System Diseases / Q000209:etiology / Q000662:veterinary*; D016022:Case-Control Studies; D006734:Horse Diseases / Q000209:etiology*; D006736:Horses; D009525:Niacin / Q000172:deficiency*; D006109:Poaceae
chemical_list: D009525:Niacin
keywords: B vitamins; dysautonomia; grass sickness; horse; niacin; nicotinic acid