Histomorphological studies of the perinatal pig: the unaffected pig

In an attempt to further elucidate the causes of perinatal mortality in pigs, a histomorphological study of organs from normal 0.4 to 60 h old euthanized piglets and from perinatal dead/euthanized pigs belonging to different mortality groups was performed. The heart, lung, liver, kidney, spleen, thymus, pancreas, thyroid and adrenal glands were studied; all sections were examined without previous knowledge of the cause of death. Different observations in the organs were judged according to a scale of 1 to 4 where 1 = none or significant and 4 = a high degree of specific organ characteristics. The percentage of the group examined that scored 3–4 was calculated for each organ characteristic, and with the help of covariance analysis adjusted for the linear effect of total body weight (at the time of death), age, gestation length, and litter size (all pigs born, alive or dead). This first report describes the observations for the euthanized normal animals.     

Blood serum characteristics of newborn pigs: comparison of unaffected pigs with pigs belonging to five mortality groups.

The blood serum levels of glucose, hemoglobin, insulin, cortisol, albumin, alpha-fetoprotein, alpha 2-macroglobulin f and s, alpha 2-antitrypsin inhibitor and alpha 1-protease inhibitor were determined at birth in 5 clinically and morphologically identified mortality groups of pigs. These were compared with the levels observed in unaffected, apparently normal newborn unsuckled pigs. The blood serum profile of the pigs in the stillborn intra partum, weak, splayleg and trauma groups, respectively, as well as that of clinically normal splayleg littermates, differed significantly from that of the unaffected pigs. This was especially true for the levels of hemoglobin and the two macroglobulins. The importance of placental insufficiency causing chronic episodes of hypoxia which ultimately lead to a disturbance in organ development in the etiology of the mortality groups is discussed.     

Lesions in the central nervous system associated with perinatal lamb mortality

OBJECTIVE: To identify and describe the occurrence of neurological lesions that could have an effect on lamb mortality. PROCEDURE: The central nervous system was investigated macroscopically (n = 92) and microscopically (n = 72) in lambs dying in the perinatal period during 3 years in flocks of adult Corriedale ewes. The central nervous system was removed intact and samples of cerebral cortex, basal ganglia, thalamus, hippocampus, mesencephalon, cerebellar cortex, medulla oblongata, and cervical spinal cord were scored microscopically for the severity of neuronal dead, cytotoxic and perivascular oedema, and haemorrhage. RESULTS: Neurologic findings between birth and 6 days included haemorrhages in meninges, brain congestion and oedema, neuronal ischemic necrosis, intraparenchymal haemorrhages in medulla oblongata and cervical spinal cord, parasagittal cerebral necrosis, and periventricular leukomalacia. No significant lesions were found in anteparturient deaths or in those aged between 7 and 16 days. Oedema was more severe in the brain than in other regions of the central nervous system. Ischaemic neurons first appeared 24 hours post partum, increased linearly in number between 48 hours and 5 days post partum, and had a laminar distribution in the cerebral cortex, indicating a hypoxic-ischemic encephalopathy. Haemorrhages were most severe in the gray matter of medulla oblongata and cervical spinal cord, suggesting trauma due to instability of atlantoaxialis joint. CONCLUSION: Lesions in the central nervous system can explain most deaths at birth and within 6 days of birth. The lesions were hypoxic-ischemic and appeared to be related to birth injury.