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.