Neuropathological changes associated with the neonatal maladjustment syndrome in the thoroughbred foal

A neuropathological investigation was carried out on the brains of 18 foals suffering from the neonatal maladjustment syndrome and results were compared with those obtained from the brains of nine foals dying from other causes. Necrosis of the cerebral cortex of an ischaemic nature was found in nine of the neonatal maladjustment foals, frequently accompanied by local haemorrhage. In three of this group of foals there was also necrosis in the diencephalon and brain stem. In the brains of the nine other affected foals there was haemorrhage in the cerebrum and sometimes in the brain stem and cerebellum; in four animals there was also brain swelling or oedema. In the control gorup, significant haemorrhage in the brain was the only finding in two foals, one premature and one stillborn apart from minimal ischaemic damage in the latter. The nature of the CNS damage in the neonatal maladjustment syndrome is considered in the light of recent experimental evidence. Although the cause is unknown it may be related to circulatory disturbances induced in the foal at the time of birth.