Results from lab tests confirm that the first of three dead bison found in the Yellowstone River did not die from malignant catarrhal fever (results on the other two bison are pending and expected within one to two weeks).

Officials say the exact cause of death could not be determined from tissue samples. However, there was no sign of disease.

The only evidence of abnormality on the carcass – visible to FWP Wildlife Veterinarian Jennifer Ramsey – was trauma to the animal’s pelvis.

Within the past two weeks, three dead bison were spotted in the Yellowstone River.

With two separate efforts, FWP crews were able to get tissue samples from each bison: the first near Emigrant, and the other two closer to Gardiner.

Ramsey also documented trauma to these other two bison in the form of broken ribs in one, and a fractured pelvis in the other. She believes these traumas were suffered before death.

Given the recent introduction of domestic sheep in the Gardiner area, FWP looked into the possibility of malignant catarrhal fever in these bison.

Malignant catarrhal fever is a viral disease which may be carried by domestic sheep without any symptoms, but can cause fatal infections in bison.