Perinatal mortality in lambs of ewes exposed to cultures of Diplodia maydis (= Stenocarpella maydis) during gestation. A study of the central-nervous-system lesions

Abstract

Previously published results of dosing trials, involving 82 ewes, revealed that 66% of the offspring of dams exposed to cultures of Diplodia maydis in the second trimester of pregnancy and 87% of lambs of ewes exposed in the third trimester, were born dead or died soon afterwards. Spongiform degeneration of myelin of varying degree was present in the brains of all the stillborn and non-viable lambs in these trials. Myelin lamellae were separated at the intraperiod line. The spongiform degeneration occurred throughout the central nervous system in severely affected animals, whereas in mildly affected lambs the lesions had a predilection for the white matter, particularly of the cerebellum and cerebrum. In 28 lambs the spongiform degeneration progressed to lytic necrosis, and hydrocephalus was recorded in two animals.