NDOW Investigates Health Concerns in Bighorn Sheep

The Nevada Department of Wildlife is worried about the health of desert bighorn sheep living in the River Mountains between the city of Henderson and Lake Mead. Though biologists do not yet know exactly what is occurring within that herd, they are concerned that some animals may have contracted pneumonia, a disease that has serious and possibly deadly implications for bighorn sheep.

Biologists have observed sheep exhibiting such troubling symptoms as coughing and nasal discharge. Members of the public have reported similar observations; however, these symptoms alone are not enough to make a reliable diagnosis. They also are indicative of other less threatening illnesses.

"A runny nose is one thing, but pneumonia is another," said Dr. Peregrine Wolff, State Wildlife Veterinarian. "The only sure way to make a firm diagnosis is to test samples from all tissues while testing for all pathogens, especially those that we know have caused pneumonia. Unfortunately, taking samples with cotton swabs or through blood samples is not enough. This situation requires that we complete a full necropsy on at least one sick adult and perhaps a couple that are young of the year."

A necropsy is an autopsy that is performed on animals; therefore, NDOW biologists will need to euthanize one or more animals in order to complete the testing process.

Additional factors fueling biologists’ concerns are the discoveries of sheep carcasses in the River Mountain that have tested positive for the bacteria Mycoplasma ovipneumoniae. Research has shown that Mycoplasma ovipneumoniae along with Pasteurella bacteria is strongly associated with pneumonia outbreaks in populations of free-ranging bighorn sheep throughout the western United States. "An in-depth study of a few sheep is important to help us understand a disease process that could potentially impact a sheep herd that is important to all of Nevada," said Wolff.

The River Mountain bighorn sheep herd has played a central role in the recovery of bighorn sheep statewide. When NDOW started its trapping and transplant program in 1967, there were less than 3,000 bighorn sheep statewide. Today that number is more than 11,000 animals. The herd also is an important economic and cultural resource for people of Boulder City.

Since much of the River Mountain Range lies within the Lake Mead National Recreation Area, NDOW will coordinate its sampling efforts with biologists from the National Park Service.

The Nevada Department of Wildlife (NDOW) protects, restores and manages fish and wildlife, and promotes fishing, hunting, and boating safety. NDOW’s wildlife and habitat conservation efforts are primarily funded by sportsmen’s license and conservation fees and a federal surcharge on hunting and fishing gear. Support wildlife and habitat conservation in Nevada by purchasing a hunting, fishing, or combination license. Find us on Facebook, Twitter or visit us at www.ndow.org.