Send to

Choose Destination
Biol Open. 2016 Jun 15;5(6):745-55. doi: 10.1242/bio.018234.

Role of carriers in the transmission of pneumonia in bighorn sheep (Ovis canadensis).

Author information

Department of Veterinary Microbiology & Pathology, Washington State University, Pullman, WA 99163, USA.
Paul G. Allen School for Global Animal Health, Washington State University, Pullman, WA 99163, USA.
Department of Veterinary Microbiology & Pathology, Washington State University, Pullman, WA 99163, USA


In the absence of livestock contact, recurring lamb mortality in bighorn sheep (Ovis canadensis) populations previously exposed to pneumonia indicates the likely presence of carriers of pneumonia-causing pathogens, and possibly inadequate maternally derived immunity. To investigate this problem we commingled naïve, pregnant ewes (n=3) with previously exposed rams (n=2). Post-commingling, all ewes and lambs born to them acquired pneumonia-causing pathogens (leukotoxin-producing Pasteurellaceae and Mycoplasma ovipneumoniae), with subsequent lamb mortality between 4-9 weeks of age. Infected ewes became carriers for two subsequent years and lambs born to them succumbed to pneumonia. In another experiment, we attempted to suppress the carriage of leukotoxin-producing Pasteurellaceae by administering an antibiotic to carrier ewes, and evaluated lamb survival. Lambs born to both treatment and control ewes (n=4 each) acquired pneumonia and died. Antibody titers against leukotoxin-producing Pasteurellaceae in all eight ewes were 'protective' (>1:800 and no apparent respiratory disease); however their lambs were either born with comparatively low titers, or with high (but non-protective) titers that declined rapidly within 2-8 weeks of age, rendering them susceptible to fatal disease. Thus, exposure to pneumonia-causing pathogens from carrier ewes, and inadequate titers of maternally derived protective antibodies, are likely to render bighorn lambs susceptible to fatal pneumonia.


Antibodies; Bighorn sheep; Carrier; Mycoplasma; Pasteurellaceae; Pneumonia

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center