For the Health of It
10 • Walking On
Consequences of Vitamin E Deficiency Reprinted with permission from Volume 30 , Issue Number 1 of Equine Disease Quarterly
Vitamin E is an essential nutrient for horses . This antioxidant helps maintain normal neurological function by limiting the damage caused by oxidative stress and free radicals . The best source of vitamin E is fresh green grass . Horses that graze on lush green pastures often have adequate access to vitamin E . However , many stabled horses are not maintained on pasture . Vitamin E levels decrease and eventually are lost as soon as grass is harvested , so even the highest-quality hay will not meet vitamin E requirements . Some horses maintained on diets deficient in vitamin E can experience significant health consequences .
Vitamin E helps a horse ’ s muscles and nerves function properly . A dietary deficiency can lead to three specific diseases : ( 1 ) equine neuroaxonal dystrophy / equine degenerative myeloencephalopathy ( eNAD / EDM ), ( 2 ) equine motor neuron disease ( EMND ) and ( 3 ) vitamin E deficient myopathy ( VEM ). These diseases are typically diagnosed based on clinical signs , exclusion of other disorders , and low concentrations of vitamin E in the blood .
Equine neuroaxonal dystrophy / equine degenetive myeloencephalopathy occurs in young animals and has a genetic predisposition . Affected horses may stand with forelimbs too far apart ( or too close together ), have difficulty navigating curbs or hills , or lack coordination while walking and making tight turns . Signs of the disease can vary , some horses show mild performance issues , while others are severely debilitated . Although the exact cause of the degeneration is unknown , a specific interaction between genetics and nutrition during the first few years of life is required for this disease to manifest .
Researchers in the Finno Laboratory are working to develop a genetic test for eNAD / EDM . Until one is available , the recommendation is to provide vitamin E supplementation to horses that do not have regular access to pasture , especially pregnant mares and newborn foals . This may not eliminate the disease , but it appears that less severe neurological signs may develop if foals receive supplementation during the early stages of life .
Equine motor neuron disease typically occurs in older horses that have been vitamin E deficient for more than 18 months . The disease affects lower motor neurons , which are nerves that supply the direct neurological input into all muscles . In their absence , the associated muscles atrophy , resulting in the clinical signs of weakness and weight loss characteristic of this disease . Affected horses may carry their heads low and lie down for longer periods . Research from Cornell University has shown that approximately 40 % of horses affected by EMND improve with vitamin E supplementation , 40 % stabilize but remain disfigured , and 20 % progress in disease severity .
Vitamin E deficient myopathy is typically found