In this episode of Tox Talk on Bovine Science with BCI, Dr. Brad White and Dr. Scott Fritz discuss a case where a group of cow-calf pairs was turned out onto pasture, and several adult cows died suddenly while calves remained unaffected, pointing away from infectious disease. With no lesions found on necropsy, the veterinarians focused on toxic causes, especially those affecting cardiac function, oxygen delivery, or neurotransmitters. Clues from rumen contents and a pasture walk led to the discovery of Japanese yew trimmings in a dump pile, a highly toxic plant that causes rapid cardiac death. The case highlights the importance of environmental investigation and recognizing toxic plant risks in grazing systems.