Half of Minnesota Zoo reindeer herd killed by seasonal disease, other half infected

APPLE VALLEY, Minn. (FOX 9) - Half of the reindeer herd at the Minnesota Zoo has died in recent weeks from a seasonal disease and the remaining members of the herd are also infected and are now being isolated from the zoo’s other animals, according to officials.

Lab tests show the entire eight-reindeer herd has been infected with Epizootic Hemorrhagic Disease, also known as EHD, which affects members of the deer family, according to the state Board of Animal Health. The disease has no known health risks to humans.

The disease was first detected in late August when the herd’s veterinarian noticed a male reindeer appeared sick. 

After the reindeer died, the University of Minnesota Veterinary Diagnostic Laboratory performed a necropsy on the animal and detected EHD, which was later confirmed by federal officials. Since then, three other reindeer in the herd have died. 

"The sudden onset of this disease and loss of our reindeer has been an extraordinarily difficult development in a difficult year,” Minnesota Zoo Director John Frawley said in a statement. 

Board of Animal Health officials say the virus that causes the disease is transmitted between deer by biting midges, or gnats, which are most active in the fall the first frost of the season.  

The zoo moved the remaining infected reindeer as well as two caribous out of the exhibit they share on the Northern Trail and is isolating them from the remaining animals in the deer family at the zoo, such as moose. The zoo also mowed the grass in the enclosure and is planning to treat the area with insecticide to reduce the gnat population.

Zoo spokesperson Zach Nugent said the caribou have also been tested for EHD, but the test results have not come back yet. 

EHD is fatal in deer, but can also affect other hoofed mammals. Nugent said the zoo all its hoofed mammals, including the bison herd as bison can also die from the disease. 

There is no specific treatment or vaccine available in the U.S. for EHD.