Equine Neonatal Maladjustment Syndrome Study Guide

Overview and Clinical Importance

Neonatal Maladjustment Syndrome (NMS), also known as hypoxic ischemic encephalopathy (HIE), perinatal asphyxia syndrome (PAS), or colloquially as "dummy foal syndrome," is one of the most common noninfectious neurological disorders affecting neonatal foals. This syndrome affects approximately 1-5% of all equine births and represents a significant topic on the NAVLE examination.

Affected foals exhibit behavioral abnormalities and neurologic deficits that are not attributable to infectious, toxic, congenital, or metabolic causes. The historical terminology of "barkers," "wanderers," "convulsants," and "dummy foals" reflects the clinical presentation spectrum observed in these patients.

Pathophysiology

Traditional Hypoxic-Ischemic Theory

The traditional understanding centers on hypoxia and ischemia occurring during the perinatal period. Decreased oxygen delivery to the fetal brain results in a cascade of cellular injury.