Placentitis remains one of the leading causes of late-term pregnancy loss, premature delivery, and neonatal disease in horses, yet early diagnosis and effective intervention remain significant clinical challenges. Our research program seeks to improve the understanding, diagnosis, and management of placental disease by integrating immunology, molecular biology, and clinical research. We have investigated the inflammatory and transcriptomic changes that occur within the infected placenta, identifying key immune pathways, cytokines, and molecular regulators involved in disease progression and placental dysfunction. Building on these discoveries, our laboratory has developed and validated maternal blood biomarker panels—including inflammatory cytokines, endocrine markers, and acute phase proteins—to facilitate earlier, minimally invasive detection of placentitis before the onset of clinical signs. Our work spans both experimentally induced and naturally occurring ascending and nocardioform placentitis, incorporating large-scale longitudinal studies involving more than 1,000 mares to evaluate disease progression, treatment response, and pregnancy outcome. More recently, our research has expanded to investigate how placental inflammation influences fetal immune development and long-term offspring health, using equine placentitis as both a clinically relevant disease model for the horse and a valuable translational model for maternal–fetal inflammatory disorders and preterm birth in human medicine.