Investigating the Risk of Equine Motor Neuron Disease in a Brazilian Stable and Successful Intervention

Abstract

We carried out an investigation to identify the factors that predispose to the risk of equine motor neuron disease (EMND) and evaluated the long-term impact of an intervention. Data on several biomarkers, including antioxidants (α-tocopherols, β-carotenes, glutathione peroxidase (GSHPx)), and superoxide dismutase (SOD1), neurofilaments, and other putative risk factors hypothesized to associate with the likelihood of EMND were collected. The data were analyzed for their significance of association with the condition. The EMND outbreak started in 1991 and continued until 1998. A total of 69 EMND cases and 64 control horses met the inclusion criteria and were enrolled in the study. Most cases (74%) occurred in 1996 and 1997. Horses afflicted with EMND had significantly lower plasma levels of vitamin E than control horses (0.381 vs. 1.148 μg/mL). There were no significant differences in the levels of vitamin A, β-carotenes, GSHPx, or the activities of SOD1 between EMND cases and control horses. Horses afflicted with EMND had significantly higher serum levels of phosphorylated neurofilament heavy than controls (2.85 vs. 0.27 ng/mL). The probability of EMND diagnosis increased above 50% when the serum levels of phosphorylated neurofilament heavy increased beyond 2.54 ng/mL. Mixed and Brazilian breeds had a significantly higher risk of EMND in comparison to Standardbred horse among the study population. In 1997, there was a change in the diet where better quality green hay was used. The incidence of EMND dropped to 0 in 1 year after intervention and remained at that level for the past 20 years.