None of the three bison found in the Yellowstone River downstream from Gardiner, Montana last month died from malignant catarrhal fever. Lab results regarding the second and third bison tested echo the results of the first bison tested. In all three cases, the tissues show no sign of disease and game officials say the exact cause of death cannot be determined. However, Montana Fish Wildlife and Parks Wildlife Veterinarian Jennifer Ramsey says all three bison showed visible signs of trauma. Ramsey says she believes this trauma – including fractured pelvises on two bison and crushed ribs on a third – occurred before death and could have resulted from the animals being swept into rocks during high water or other blunt force trauma. Every year, animal carcasses wash downstream from Yellowstone National Park into Montana.