Summary Hypoxic ischaemic encephalopathy ( HIE ) has been described in foals for over 80 years. This condition has a diversity of names including ‘dummy foals', ‘wanderers', ‘barkers', neonatal encephalopathy, neonatal maladjustment syndrome ( NMS ) and perinatal asphyxia syndrome ( PAS ). The latter descriptive terms are all encompassing for a syndrome that has varying degrees of multi‐systemic effects rather than just neurological disease. While foals with PAS are commonly reported in the literature, the aetiology and underlying pathophysiology are still very poorly understood, with a majority of the information extrapolated from human and animal models. Currently, no antemortem test exists and diagnosis is made based on the history of the mare and foal as well as reliance on clinical signs. Recent studies have shown that neuroactive pregnanes may play a key role in the syndrome; however, further research is needed to clarify these findings. Another investigation compared neurobiomarkers for brain injury in both sick and normal neonatal foals. The mainstay of therapy for PAS is supportive treatment. Specific therapies such as antioxidants and neuroprotectants are used by some clinicians but little scientific evidence exists that proves the therapeutic protocols implemented improve overall outcome. Prevention of PAS in foals revolves around the health of the mare including, but not limited to, the prevention of placentitis or other illnesses and observation and/or intervention during parturition when necessary. More research is necessary to fully comprehend this syndrome, its diagnosis and treatment options.