Montana agency rules out fever in 1 bison death

BOZEMAN (AP) — Montana wildlife officials said Tuesday they have ruled out a disease transmitted by sheep as the cause of death of a bison found in the Yellowstone River.

Fish, Wildlife and Parks veterinarians reached the conclusion while investigating whether the introduction of sheep on land north of Yellowstone National Park had resulted in the spread of catarrhal fever to three dead bison.

Sheep can carry the fever without showing any symptoms, but it can be fatal if transmitted to bison. The Gallatin Wildlife Association had called for the investigation to protect against a possible outbreak.

In mid-April, a rancher introduced about 30 sheep to his property that borders Yellowstone River near Gardiner. The dead bison were found downstream earlier this month in or near the river.

The cause of death could not be determined in the first bison found near Emigrant, but lab results indicated there was no sign of disease, FWP Veterinarian Jennifer Ramsey said.

She said there was evidence of trauma to the bison's pelvis, and the animal probably suffered from hemorrhaging before it died.

The other two animals sustained similar injuries, she said, resulting in broken ribs and punctured lungs in one and a broken pelvis in the other.

Results of lab tests on those two bison will be released within two weeks.

Ramsey speculated the bison were standing in the river when they were swept away in spring floods. The animals' injuries may have been due to hitting hard surfaces, she said.

The two remaining bison will be tested for anthrax, which the animals can pick up from nature.

If those tests are negative, internal organs will be examined for catarrhal fever or another infection, Ramsey said.