Neurodegeneration in equine grass sickness is not attributable to niacin deficiency

B C McGorum, R C Jago, E Cillan-Garcia, R S Pirie, J A Keen, R J M Reardon, P Y Saffu, N. J. Miller

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

BACKGROUND: The aetiology of equine grass sickness (EGS) is currently unknown. We hypothesised that acute deficiency of niacin (vitamin B3), which has a key role in neural homeostasis, may contribute to neurodegeneration in EGS. Niacin deficiency could potentially result from ingestion of niacin antagonists produced by pasture mycotoxigenic fungi.

OBJECTIVES: 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.

STUDY DESIGN: 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 inter-group difference in the NAD:NADP ratio, the main index of functional niacin status (control median 2.1, interquartile range 1.8-2.6; EGS 2.1, 1.9-2.6). EGS horses had significantly higher (median value increased by 25%) concentrations of NADP. There were no inter-group differences in blood concentrations of vitamins B1, B2 and B6.

MAIN LIMITATIONS: Interpretation of data was limited by 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. This article is protected by copyright. All rights reserved.

Original languageEnglish
Pages (from-to)445-447
JournalEquine Veterinary Journal
Issue number4
Early online date16 Aug 2016
Publication statusPublished - Jul 2017

Keywords / Materials (for Non-textual outputs)

  • horse
  • grass sickness
  • dysautonomia
  • B vitamins
  • niacin
  • nicotinic acid


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