abortion in dairy cattle due to neospora caninum: diagnostic challenges

Neosporosis, caused by the obligate intracellular protozoan, namely n. caninum, is a major factor in bovine fetus abortions, posing a threat to the dairy industry s economy. infected guards and free-roaming dogs near or within dairy farms can introduce infectious oocysts to cows feed and water. both horizontal and vertical transmission of n. caninum in cattle can result in mid- to late-term abortion due to infection of the placenta and fetus or in the birth of unthrifty neonates with neurologic symptoms. a meta-analysis reports 24.2% prevalence in cattle and 19.9% in dogs in diverse provinces of iran. the disease affects domestic animals and canines, impacting human health and the economy, so each report provides valuable insights into its status in different areas. detecting neospora caninum in bovine abortion is difficult؛ hence, a comprehensive approach with various diagnostic methods is essential for accurate detection in such cases. postmortem examination of four approximately 5-6 month old aborted holstein friesian fetuses revealed the accumulation of serosanguinous fluid in the body cavities, particularly the thorax. the samples from several tissues are taken for further investigations. in histopathology findings, the placenta showed scattered lymphocytes within the intercotilodonary region with eroded trophoblasts and multifocal trophoblast necrosis. the liver and lungs had mononuclear cells (lymphocytes) infiltrating within the hepatic portal areas and interstitial tissues, respectively. the heart notably showed nonsuppurative lymphocytic myocarditis. the brain represented multifocal areas of necrosis surrounded by mononuclear inflammatory cells and severe multifocal gliosis. pcr testing was negative for bvd but positive for neospora caninum. the diagnosis was abortion due to neospora caninum. after further inquiries with the breeder, we discovered that dogs and possibly other canids have access to cows stored feeds. our recommendation aligns with enhancing farm biosecurity by improving enclosures through fencing.