Blood and Cerebrospinal Fluid α‐Tocopherol and Selenium Concentrations in Neonatal Foals with Neuroaxonal Dystrophy

Background Equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy ( NAD / EDM ) is a neurodegenerative disorder affecting genetically predisposed foals maintained on α‐tocopherol (α‐ TP )‐deficient diet. Objective Intramuscular α‐ TP and selenium ( S e) administration at 4 days of age would have no significant effect on serum or cerebrospinal fluid ( CSF ) α‐ TP in healthy foals. Serum and CSF α‐ TP , but not Se, would be significantly decreased in NAD / EDM ‐affected foals during first year of life. Animals Fourteen Quarter horse foals; 10 healthy foals supplemented with 0.02 mL/kg injectable α‐ TP and S e (n = 5) or saline (n = 5) at 4 days of age and 4 unsupplemented NAD / EDM ‐affected foals. Methods Complete neurologic examinations were performed, blood and CSF were collected before (4 days of age) and after supplementation at 10, 30, 60, 120, 180, 240, and 360 days of age. Additional blood collections occurred at 90, 150, 210, and 300 days. At 540 days, NAD / EDM ‐affected foals and 1 unsupplemented healthy foal were euthanized and necropsies performed. Results Significant decreases in blood, CSF α‐ TP and S e found in the first year of life in all foals, with most significant changes in serum α‐ TP from 4–150 days. Dam α‐ TP and S e significantly influenced blood concentrations in foals. Injection of α‐ TP and S e did not significantly increase CSF S e, blood or CSF α‐ TP in healthy foals. NAD / EDM ‐affected foals had significantly lower CSF α‐ TP through 120 days. Conclusions and Clinical Importance Injection of α‐ TP and S e at 4 days of age does not significantly increase blood or CSF α‐ TP . Despite all 14 foals remaining deficient in α‐ TP , only the 4 genetically predisposed foals developed NAD / EDM .