WGFD monitors Bighorn Sheep herd
Jackson bighorn sheep herd showing signs of pneumonia
by Wyoming Game and Fish
March 21, 2010
JACKSON – The Wyoming Game and Fish Department is cautiously monitoring a small group of sheep in the Jackson bighorn sheep herd after some animals were showing signs of pneumonia recently. The Jackson herd experienced a die-off due to pneumonia during the winter of 2001-2002 when biologists estimated losing as many as half of the herd that numbered approximately 500 at the time. Similarly, the Whiskey Basin herd in the Wind River Range near Dubois has struggled through several bouts with the disease over the years.
According to Wyoming Game and Fish Wildlife Disease Specialist, Hank Edwards, pneumonia may be what kills a bighorn sheep, but recovery and identification of the original pathogen can sometimes be very difficult. In an effort to collect tissue samples and identify the initial pathogen, Wyoming Game and Fish officials lethally removed two male lambs from the herd last week that were coughing and exhibiting signs of pneumonia.
"Unfortunately, removing sick animals is the only way to have a chance at identifying the original pathogen because it can be easily masked by other bacteria as the disease progresses," said Edwards. "Of course, it’s important to identify the original pathogen in order to know what management options you might have for containing the disease."
Currently, culture tests are being performed on tissues taken from the two lambs at the Wyoming State Veterinary Laboratory in Laramie. Through the culture process, researchers hope to grow and identify any potential disease agents. "So far, we are not seeing any of the Pastuerella/Mannheimia bacteria, which are often associated with bighorn sheep pneumonia outbreaks and die-offs," said Edwards. "We did identify some lungworms, which is not too surprising, and they were not heavy loads, so that was good."
"Although it is not uncommon for sheep to show signs of pneumonia, the fact that this herd has already experienced a significant die-off, and that other western states have been reporting similar problems this winter, did raise our level of concern," said Wyoming Game and Fish Wildlife Biologist Doug Brimeyer. "The preliminary results on the tissues samples are encouraging, plus the fact that we’re experiencing a relatively mild winter and early spring should help these sheep as well."
Wyoming Game and Fish officials currently estimate the Jackson bighorn sheep herd at approximately 420 animals, which includes animals in both the Gros Ventre and northern Wyoming Range mountains. "Fortunately, it still appears to be a fairly localized issue specific to the Russold Hill area in the Gros Ventre," said Brimeyer. "We will continue to watch these sheep closely and keep an eye out for other sheep that may be showing signs of pneumonia as well."