Fellow, Large Animal Neurology New Bolton Center, University of Pennsylvania School of Veterinary Medicine West Chester, Pennsylvania, United States
Background - Three commonly diagnosed equine neurologic conditions in North American horses are cervical vertebral stenotic myelopathy (CVSM), equine protozoal myeloencephalitis (EPM) and equine degenerative myeloencephalopathy (EDM)/equine neuroaxonal dystrophy (eNAD), which are often clinically indistinguishable. EDM/eNAD is a diagnosis of exclusion with no confirmatory antemortem biomarkers. Cell-free DNA (cfDNA) has been associated with neurodegeneration in other species, though no studies have examined its utility in equine cerebrospinal fluid (CSF).
Hypothesis/Objectives – The objectives were to determine if equine CSF cfDNA concentrations are detectable and differ significantly between healthy control horses and those with common neurologic diagnoses, and if cfDNA is a candidate biomarker for EDM/eNAD. We hypothesized that cfDNA concentrations would be quantifiable and significantly higher in horses with EDM/eNAD compared with healthy controls and other disease states.
Animals – 45 client-owned horses with confirmed diagnoses
Methods – Case-controlled study design. Fluorometry was used to determine biobanked CSF cfDNA concentrations from four groups (neurologically normal, CVSM, EPM and EDM/eNAD) which were compared using ANOVA and Kruskal-Wallis statistics.
Results – There were no significant differences in CSF [cfDNA] (median, IQR) between horses with EDM/eNAD (25.65 ng/mL, 18.28-30.38), CVSM (23.95 ng/mL, 17.84-37.81) or EPM (34.90 ng/mL, 29.84-37.61) and neurologically normal controls (34.95 ng/mL, 15.85-45.9), nor between disease groups (P>0.05)(Figure 1).
Conclusions and clinical importance – This study is the first to evaluate cfDNA in equine CSF. Although cfDNA is a burgeoning research area, these data do not support its candidacy as a biomarker for equine neurodegenerative disease where further efforts are needed.
