• Steam rises off of the colorful Mammoth Hot Springs Terraces. Photo courtesy Jacob W. Frank


    National Park ID,MT,WY

New Study Shows Distemper Linked to Wolf Pup Deaths

Subscribe RSS Icon | What is RSS
Date: September 16, 2009
Contact: Al Nash, 307-344-2015
Contact: Stacy Vallie, 307-344-2015

National Park Service
U.S. Department of the Interior

Yellowstone National Park
P.O. Box 168
Yellowstone National Park, WY 82190
September 16, 2009   09-088
Al Nash or Stacy Vallie (307) 344-2015


New Study Shows Distemper Linked To Yellowstone Wolf Pup Deaths

Since wolves were reintroduced in Yellowstone in the 1990s, there have been three years when the pup survival rate was extremely low: 1999, 2005, and 2008.

Canine parvovirus was believed to be the cause of the wolf pup deaths in 1999 and 2005. That was because parvovirus is known to cause a high mortality rate in domestic dogs, and was suspected in the high death rate of wolves at Isle Royale National Park in Michigan in the early 1980s. 

Results of newly published research point to canine distemper as the cause of the low pup survival rates.

Researchers took blood samples from wolves and coyotes in Yellowstone National Park. They looked for exposure to a number of canine diseases. The results indicate that some diseases like parvovirus are chronic in the park’s wild canines.

However, signs of distemper appeared only in the years when pup mortality was high. Since distemper weakens the immune system and makes infected animals susceptible to other infections, it can be difficult to determine the actual cause of death.

The research also indicates that the wolf population seems to fare well despite some chronic infections, and rebounds well from periodic exposure to distemper.

While the research was unable to conclusively determine the episodic source of the canine distemper, data suggests it is not linked to the region’s domestic dog population.

The research was conducted by the Yellowstone Wolf Project, the University of Minnesota, and the Yellowstone Ecological Research Center. The findings were recently posted to PLoS ONE, a peer-reviewed online journal which posts reports of original research in science and medicine: http://www.plosone.org/article/info:doi/10.1371/journal.pone.0007042.

- www.nps.gov/yell -

Did You Know?