Safeguarding Okanagan Bighorn Sheep: Inside the Psoroptes Mange Treatment Initiative
- kylestelter
- Dec 12
- 3 min read
The Okanagan Valley is home to one of British Columbia’s most culturally and ecologically significant wildlife species—yilíkʷlxkn, the California Bighorn Sheep. For the Syilx Nation and for our conservation community, these sheep represent a deep connection to land, culture, and biodiversity. Yet today, these herds face mounting pressures from habitat loss, disease, and human-introduced threats.
One of the most pressing challenges is Psoroptic mange, a debilitating skin disease caused by the non-native mite Psoroptes cuniculi. For more than two decades, this parasite has persisted within the Ashnola-Similkameen and South Okanagan herds, contributing to declining condition, poor lamb recruitment, and elevated mortality. Because this parasite is not naturally occurring in bighorn sheep, affected animals have no natural resistance—a reality that has driven the need for active, science-based intervention.
Recently, the Okanagan Nation Alliance (ONA), in partnership with WSSBC, WLRS, Syilx communities, the Wild Sheep Foundation, and many other collaborators, released a comprehensive update on this critical treatment initiative. You can read the full report here: Psoroptes Report – December 2025 Psoroptes report December 2025
A Collaborative Effort Rooted in Stewardship
Across the region, only about 700 bighorn sheep remain, and disease is a major factor in long-term herd stability. The report highlights that Psoroptes mange, along with other risks such as EHD and Mycoplasma ovipneumoniae, threatens the viability of multiple Okanagan herds.
But it also illustrates something powerful: a united response.
Through shared stewardship and collaboration, Syilx leadership, biologists, veterinarians, volunteers, and conservation organizations have advanced one of the most ambitious wildlife disease management programs in Canada.
Key actions to date include:
Maintaining and deploying GPS collars to monitor disease spread, movement, recruitment, and mortality.
Building and repairing large handling pens to support research and treatment.
Capturing and caring for 28 bighorn sheep for controlled clinical trials—11 of which have since produced healthy lambs.
Establishing a transboundary working group with Washington State partners to address cross-border disease risks.
Advancing new science on long-term treatment options to potentially eliminate Psoroptes from wild herds.
Inside the Clinical Drug Trial
The heart of the initiative is a 15–18 month clinical trial evaluating two promising treatments—Fluralaner (FLEXOLT®) and long-acting Moxidectin. These drugs aim to:
Clear Psoroptes infestations with a single treatment
Prevent re-infestation for as long as possible
Inform a scalable treatment plan for free-ranging herds across the Okanagan
As detailed in the report, 37 sheep were placed into four research pens and assigned specific treatments. Early observations already show significant improvement in hair condition among treated animals, a hopeful sign for broader population-level gains.
These trials not only inform disease management—they also strengthen our long-term goal of restoring healthy, self-sustaining herds across Syilx and British Columbia landscapes.
Why This Work Matters
The Psoroptes infestation began through human introduction more than 20 years ago. Because it is not naturally occurring in bighorn sheep, we have a responsibility to act.
Left untreated, mange reduces fitness, increases predation risk, undermines lamb recruitment, and can slowly erode populations over time. The science is clear: this disease will not resolve on its own.
The work described in this report demonstrates:
Innovation in wildlife health research
Cultural responsibility upheld by the Syilx Nation
Collaborative conservation across governments, NGOs, and communities
Hope—that with the right tools and commitment, we can reverse the impacts of a long-standing, human-caused disease
A Community Effort
As highlighted on the final pages of the report, this initiative is powered by dozens of partners, volunteers, and donors—from Indigenous communities to outfitters, NGOs, and conservation champions who sponsored individual animals through the “Adopt a Sheep” program.
This work is what happens when a community comes together for tmixʷ—all living things.
Read the Full Update
To learn more about the science, the trial, the partners involved, and the path forward, read the full December 2025 Psoroptic Mange Initiative Report:
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