12 sheep, goats from fire-preventing grazing herd die after poisoned by plants in Marin Co.

MARIN COUNTY, Calif. (KGO) -- At least a dozen wildfire-mitigation goats and sheep have died in the North Bay after being poisoned by plants. About 18 others are being quarantined, according to their shepherd.

For Billie Thibodeau, her herd isn't just a business.

It's a family of about 120 sheep and goats, 3 dogs, and even an emu to protect the herd from aerial predators.

"I raise them to live long happy lives. I love these animals and I want them to live the best lives possible," said Thibodeau.

For the past decade, Thibodeau's herd, better known as Scape Goat Grazing, has been her team of four-legged firefighters, nature's lawnmowers clearing out the bad.

"We saw the native plants that were allowed to grow once we cleared out all of that brush," explained Thibodeau. "All that vegetation material composing in their stomach being distributed evenly, forming the top soil."

MORE: How climate is impacting California's fire season, and a solution involving plants

Thibodeau started out with just two goats and quickly realized how she could transform neighborhoods.

"We made areas and paths to come through," said Thibodeau. "I just became really passionate about grazing at that point. Everything we do impacts the land in a positive way. It's the perfect preventative solution to wildfire."

Thibodeau believes her work shows that nature itself can be a partner in prevention, but in the last two weeks, Thibodeau's herd suffered a devastating blow. Members of her family started showing signs of illness after grazing snakeroot plants while on a project down at Stinson Beach.

"It was a private resident job on a property that hadn't been managed for decades and was very outgrown," said Thibodeau. First she lost a sheep, and in the last two weeks, she's now lost 12 sheep and goat.

"It was shocking to see," said Thibodeau. "It's just totally heartbreaking."

Thibodeau's vet Dr. Myriam Kaplan-Pasternak tells ABC7 News that she has received a preliminary toxicology report. In the report, testing shows heart damage in a sheep consistent with poisoning in snakeroot plants.

While Dr. Kaplan-Pasternak believes these plants are not a usually a problem in the Marin County area, she said abnormal seasons and temperatures lately could be affecting toxin levels and that tests will need to be done.

"This is not known to be a terribly toxic plant," said Thibodeau. "It ended up killing my animals."

The plants will also need to be sent to UC Davis to confirm the type of plant and undergo toxicology tests.

Now Thibodeau is quarantining 18 of her other sheep and goat, while keeping an eye on the rest of her herd.

"I need to watch them, boost their health immune systems now," said Thibodeau. "I rarely have sick animals because my herd is so healthy, shocking."

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Thibodeau's herd usually clears about eight acres a month, just enoguh to cover her $10,000 in monthly costs. Now, she doesn't know what she'll do.

"Those of us who do fire fuel grazing do it because we love and care about the land," said Thibodeau. "That's why a lot of people don't anymore. It's really expensive."

What keeps Thibodeau going is the love she has for this line of work and the impact her herd can have.

"Two months ago, I finished a big fire fuel project, a resident just down the hill from the Pickett Fire. "Yesterday, I talked to the owner who was worried but felt very secure, considering she hired us to graze her house."

Thibodeau said she's grateful for her clients and community who have donated to help keep her afloat.