Research Points to Canine Distemper As Cause of Low Wolf Pup Survival in Yellowstone National Park

Submitted by Kurt Repanshek on September 17, 2009 - 3:17am

Canine distemper apparently was the culprit behind high pup mortality in Yellowstone's wolf packs in 199, 2005 and 2008. NPS photo by Jim Peaco.

Canine distemper, not parvovirus, apparently was behind the high wolf pup mortality rates in Yellowstone National Park in 1999, 2005 and 2008, according to new research.

Canine parvovirus was thought to be the culprit behind the atypically high number of pup deaths in 1999 and 2005 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, according to a park release. However, newly published research points 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.

What the research was unable to answer, though, was the source of the canine distemper, the park said. However, the data suggest it was not linked to the region’s domestic dog population, adds the release.

The research was conducted by the Yellowstone Wolf Project, the University of Minnesota, and the Yellowstone Ecological Research Center. You can find the study here.