Abstract
This study evaluates the role of aoudad (Ammotragus lervia) as a maintenance host and reservoir for significant respiratory pathogens hindering bighorn sheep (Ovis canadensis) conservation; Mycoplasma ovipneumoniae and leukotoxigenic Pasteurellaceae. An experimental commingling trial and regional disease surveillance revealed significant interspecies transmission risks and epidemiological patterns. Experimentally, 80% of bighorn sheep exposed to aoudad inoculated with M. ovipneumoniae and leukotoxigenic Pasteurellaceae died of pneumonia under both indirect and direct contact conditions. Conversely, aoudad exhibited prolonged relatively asymptomatic shedding of M. ovipneumoniae without severe clinical outcomes. Surveillance of 351 free-ranging aoudad revealed 9.4% with M. ovipneumoniae DNA in nasal swabs and M. ovipneumoniae-specific antibodies in 55.8%. Aoudad diagnostic profiles were heterogeneous across populations, including variations in strain diversity and distribution. Shedding rates were higher among juveniles than adults. Aoudad can sustain and transmit M. ovipneumoniae under free-ranging and experimental conditions, presenting significant risks to bighorn sheep populations. Research on strategies to mitigate pathogen transmission, such as reducing shared water access and aoudad removal, is critical for predicting complex biological outcomes for multi-species management. This study emphasizes the importance of longitudinal herd-specific disease surveillance and fundamental pathobiology research for understanding M. ovipneumoniae dynamics in aoudad to inform bighorn sheep conservation efforts in Texas.
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Acknowledgements
We extend our deepest gratitude to Thomas Besser, Marla Francis, Daniel Bradway, and Becca Wolking of the Washington Animal Disease Diagnostic Laboratory for their invaluable guidance on the interpretation and processing of multi-locus genetic sequences. We also thank the Texas Parks and Wildlife Department Big Game Program Staff, including Cody McEntire, Mike Janis, Mark Garrett, Mitch Lockwood, and the staff at Mason Mountain and Kerr Wildlife Management Areas-Mark Mitchell, Jeff Forman, Ryan Reitz, and Spencer Wyatt-for their extensive contributions to this project. The stakeholder guidance, project coordination, agency resources, facilities, and capture support were instrumental to our success. We are immensely grateful to the volunteers who provided critical assistance with animal monitoring, capture, and care: Dr. Jamie Benn, Brianna Stofas, Lillian LePage, Rion Conley, Colton Pittman, and AJ Nunez. This research was funded by the Texas Parks and Wildlife Department’s Wildlife Research Program through Federal Aid in Wildlife Restoration Act (Pittman-Robertson) grants (TX W-207-R-1 F20AF10359-00) and the Wild Sheep Foundation’s Grant-in-Aid of Research (GIA 2021-71). We are especially thankful for the connections and support provided by Kevin Hurley and Clay Brewer. Additionally, we acknowledge the Texas Bighorn Society for their generous support of this project, particularly their contributions to project logistics and capture efforts.
Funding
This research was funded by the Texas Parks and Wildlife Department’s Wildlife Research Program through the Federal Aid in Wildlife Restoration Act (Pittman-Robertson) grants (TX W-207-R-1 F20AF10359-00) and the Wild Sheep Foundation’s Grant-in-Aid of Research (GIA 2021-71).
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This work was funded in part by the Texas Parks and Wildlife Department’s Wildlife Research Program through Federal Aid in Wildlife Restoration Act (Pittman-Robertson Act; TX W-207-R-1 F20AF10359-00). Agency officials from Texas Parks and Wildlife Department were involved in each aspect of project conceptualization, but study design and scientific interpretations were conducted under Walter E. Cook’s instruction as the senior principal investigator. The authors have no other perceived or actual competing interests to disclose.
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Thomas, L.F., Clontz, D., Nunez, C.M. et al. Aoudad (Ammotragus lervia) as disease reservoirs for bighorn sheep (Ovis canadensis): experimental and epidemiological evidence. Sci Rep (2026). https://doi.org/10.1038/s41598-026-51837-9
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DOI: https://doi.org/10.1038/s41598-026-51837-9
