Pathological changes in aborted fetuses and placental tissue in cows with neosporosis

Abstract

The failure to obtain offspring due to abortion causes considerable damage to the dairy industry worldwide, costing millions of US dollars. Neospora caninum, a protozoan parasite of the Apicomplexa class, is the causative agent of neosporosis, a disease that leads to abortions or the birth of weak offspring in cows. Therefore, addressing this issue is crucial. The purpose of this study is to describe the pathological changes in aborted fetuses and placental tissue in cows with neosporosis. Macroscopic examination of fetal and placental parts was performed through pathological dissection. The gestation age (days) was determined using the formula: 68 + 2.25×CRL (cm) and/or from historical data. DNA of N. caninum was detected by polymerase chain reaction in all fetuses and/or fetal parts of placentas described in the study. It was found that the majority of abortions occurred at 4-5 months of gestation. External examination revealed isolated instances of skin hyperemia and haemorrhages throughout the body. Some fetuses were mummified. Autolysis of the fetus and placental parts was observed in most cases. Placentitis and oedema of the placental tissue were also noted in some cases. Internal examination of fetuses revealed changes in the brain, skeletal muscles, heart, lungs, liver, spleen, and kidneys, in addition to characteristic autolysis. These changes, including grey foci in the brain with a light grey centre, white foci, and multiple white streaks in skeletal muscles and the tongue, can be attributed to typical pathological changes in aborted fetuses with neosporosis. These changes are rare but can impact the determination of the cause of abortion, narrowing down the factors responsible