Tularemia in range sheep: An overlooked syndrome?

Donal O'Toole, Elizabeth S. Williams, Leslie Woods, Kenneth Mills, Amy Boerger-Fields, Donald L. Montgomery, Paula Jaeger, William H. Edwards, Dwayne Christensen, William Marlatt

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


Abortion and death caused by Francisella tularensis were well recognized in range flocks of domestic sheep in Idaho, Montana, and Wyoming in the first 6 decades of the 20th century. The current report describes 4 episodes of tularemia in 3 range flocks in Wyoming and South Dakota in 1997 and 2007 (1 flock was affected twice). Flock owners reported that ticks were unusually numerous and commonly present on sheep during outbreaks. Tularemia presented as late-term abortions (3 episodes) or listlessness and death in lambs and, to a lesser extent, ewes (1 episode). Lesions were multifocal pinpoint necrotic foci in tissues, particularly spleen, liver, and lung. An immunohistochemical procedure demonstrated F. tularensis, particularly in necrotic foci. The diagnosis was corroborated by bacterial isolation and, in individual cases, by serology, fluorescent antibody assay, and/or polymerase chain reaction detection of F. tularensis. Diagnosticians in endemic areas should include tularemia as a differential diagnosis when investigating late-term abortions or outbreaks of fatal illness in young lambs, particularly in years of high tick activity and when characteristic necrotic foci occur in spleen, liver, and lung.

Original languageEnglish (US)
Pages (from-to)508-513
Number of pages6
JournalJournal of Veterinary Diagnostic Investigation
Issue number4
StatePublished - Jul 1 2008
Externally publishedYes


  • Abortion
  • Diagnosis
  • Francisella tularensis
  • Immunohistochemistry
  • Sheep
  • South Dakota
  • Tularemia
  • Wood tick
  • Wyoming

ASJC Scopus subject areas

  • veterinary(all)


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