This study describes the acute poisoning of four 3-month-old Franconia geese (Anser anser) by oleander plants (Nerium oleander). After the accidental ingestion of oleander clippings, the geese exhibited a rapid onset of severe symptoms, leading to mortality within 15–90 min. Necropsy revealed cardiac and renal lesions. Specifically, interstitial edema, red blood cell infiltration, and myofibril loss were observed in the cardiac muscle, and tubular epithelial degeneration, interstitial edema, and hemorrhages were evident in the kidneys. Oleandrin, a glycoside with cardiac effects, was detected in the liver, kidneys, heart, brain, and muscles. The clinical implications underscore the urgency of veterinary intervention upon oleander ingestion, and the specific findings contribute valuable insights into the pathological effects of acute oleander poisoning in geese, aiding veterinarians in prompt diagnosis and treatment.