Abstract: Background: Phosphorylated neurofilament-heavy (pNF-H), a biomarker of axonal injury and degeneration, has been proposed to assist in the diagnosis of equine neurologic disease. Previous publications suggest limited utility for neonatal hypoxic-ischemic encephalopathy and equine acute grass sickness, but increased concentrations of neurofilaments seem to occur in equine protozoal myeloencephalitis (EPM), equine motor neuron disease (EMND) and cervical vertebral stenotic myelopathy (CVSM). Recently, a pNF-H ELISA became commercially available and widely utilized, particularly for horses with suspected neurodegenerative diseases including equine neuroaxonal dystrophy/degenerative myeloencephalopathy (eNAD/EDM). However, the aid of this biomarker in the diagnosis of equine neurological diseases is uncertain.
Hypothesis/Objectives: To evaluate the clinical utility of pNF-H results in horses with neurologic disease.
Animals: 178 neurologic cases recruited from three hospitals.
Methods: This retrospective study includes horses that underwent a complete neurological evaluation. Serum and cerebrospinal fluid samples were submitted for pNF-H ELISA analysis. Postmortem diagnosis was included when available.
Results: Most neurologic horses did not have increased [pNF-H]; 15 (8%) had increased serum concentrations (>1 ng/mL) and 38 (21%) had increased cerebrospinal fluid (CSF) concentrations (>3 ng/mL; Table 1). Postmortem confirmation of diagnosis was available for 65 horses and the most common diagnosis was eNAD/EDM.
Conclusions and clinical importance: The pNF-H testing is perceived to have a low sensitivity for any specific neurologic disease but cases with increased serum pNF-H concentration have a likely diagnosis of eNAD/EDM. Further investigations need to be done on its utility for prognosis, monitoring of progression and response to treatment in equine neurologic diseases.
