A LEAP FORWARD FOR NORTHERN LEOPARD FROGS: NEW TREATMENT OFFERS HOPE AGAINST DEADLY AMPHIBIAN DISEASE
October 29, 2025
29 OCTOBER 2025 (Calgary, AB) – Near Kimberley, British Columbia, a wetland shimmers under the autumn sun. The surface appears calm, the reeds sway gently in the breeze, but beneath that stillness, the water teems with life. Young northern leopard frogs, newly transformed through metamorphosis, dart and glide through the water.
Although common across much of their eastern range, the Rocky Mountain population of northern leopard frogs is endangered in Canada under the federal Species at Risk Act. The decline of this sensitive population is likely a result of habitat loss and degradation, invasive species, and disease. In recent years, researchers noticed that despite promising summer populations, fewer frogs were surviving the winter.
“We were seeing vibrant wetlands in the summer, full of tadpoles transforming into young-of-year frogs, but by the following spring, far fewer were present,” said Rebecca Stanton, Conservation Program Manager at the Wilder Institute. “It suggested something was happening over winter, and we began to suspect chytrid fungus might be playing a role.”
An invisible threat
Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), affects the skin of amphibians — a critical organ for breathing and water regulation. Detected globally since the 1990s, the disease has contributed to the decline or extinction of over 500 amphibian species.
In 2023, testing at the frog reintroduction site near Kimberley revealed a concerning finding: every young-of-year frog sampled tested positive for Bd, with many showing clinical signs of infection such as shedding skin and lethargy. In response, the Wilder Institute’s Conservation & Science and Animal Care, Health & Welfare teams launched a small-scale study — the first of its kind in B.C. — to test in-situ antifungal treatment using itraconazole, a common antifungal medication.
Testing a new approach
A group of 53 young-of-year frogs was carefully collected and placed in outdoor temporary holding pens at one wetland within the site. Additionally, 15 frogs were collected to serve as controls. Each day, for seven days, the 53 frogs were given a short bath in a dilute itraconazole solution, a gentle treatment designed to target the chytrid fungus without harming the frogs or their environment.
After the treatment period, the frogs were released back into the broader wetlands, and samples were sent to the laboratory for analysis.
The early results were encouraging:
- Before treatment began, 75% (40 of 53) of frogs tested positive for chytrid fungus.
- After the final treatment on day seven, only 9% (5 of 53) still tested positive. Notably, at least one of the five individuals tested negative upon follow-up testing two weeks later.
Researchers at the Wilder Institute will continue conducting surveys and monitoring over the coming weeks, as well as throughout the following spring and summer, to determine whether treated frogs show improved survival compared to those that were untreated.
“We’re very hopeful about these early results,” says Stanton. “The treatment appears to be highly effective at reducing infection, and we’re optimistic it will help to improve overwinter survival for these young frogs.”
Looking ahead
This study demonstrates that with careful planning, collaboration, and persistence, targeted interventions can help at-risk species recover. Each frog returning to the wetland—chytrid-free—is a tangible sign that conservation efforts are working, offering hope for the future of the Rocky Mountain population of this endangered amphibian.
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