Journal of Veterinary Internal Medicine (May 2024)

Equine neuroaxonal dystrophy/degenerative myeloencephalopathy in Gypsy Vanner horses

  • Alexis Powers,
  • Simon F. Peek,
  • Steve Reed,
  • Callum G. Donnelly,
  • Stacey Tinkler,
  • David Gasper,
  • Kevin D. Woolard,
  • Carrie J. Finno

DOI
https://doi.org/10.1111/jvim.17062
Journal volume & issue
Vol. 38, no. 3
pp. 1792 – 1798

Abstract

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Abstract Background Equine neuroaxonal dystrophy/degenerative myeloencephalopathy (eNAD/EDM) is a neurodegenerative disease that primarily affects young, genetically predisposed horses that are deficient in vitamin E. Equine NAD/EDM has not previously been documented in Gypsy Vanner horses (GVs). Objectives To evaluate: (1) the clinical phenotype, blood vitamin E concentrations before and after supplementation and pedigree in a cohort of GV horses with a high prevalence of neurologic disease suspicious for eNAD/EDM and (2) to confirm eNAD/EDM in GVs through postmortem evaluation. Animals Twenty‐six GVs from 1 farm in California and 2 cases from the Midwestern U.S. Methods Prospective observational study on Californian horses; all 26 GVs underwent neurologic examination. Pre‐supplementation blood vitamin E concentration was assessed in 17‐ GVs. Twenty‐three were supplemented orally with 10 IU/kg of liquid RRR‐alpha‐tocopherol once daily for 28 days. Vitamin E concentration was measured in 23 GVs after supplementation, of which 15 (65%) had pre‐supplementation measurements. Two clinically affected GVs from California and the 2 Midwestern cases had necropsy confirmation of eNAD/EDM. Results Pre‐supplementation blood vitamin E concentration was ≤2.0 μg/mL in 16/17 (94%) of GVs from California. Post‐supplementation concentration varied, with a median of 3.39 μg/mL (range, 1.23‐13.87 μg/mL), but only 12/23 (52%) were normal (≥3.0 μg/mL). Normalization of vitamin E was significantly associated with increasing age (P = .02). Euthanized horses (n = 4) had eNAD/EDM confirmed at necropsy. Conclusions and Clinical Importance GVs could have a genetic predisposition to eNAD/EDM. Vitamin E supplementation should be considered and monitored in young GVs.

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