Cattle ranchers east of the Cascade Mountains spent much of the summer evacuating their herds from wildfires that scorched nearly 2 million acres. Even if the animals were moved safely away from the flames, they faced another potential danger: smoke exposure.

Across the state of Oregon, on both dairy and beef operations, cows have been getting sick, according to a news release from the Oregon State University (OSU) Extension Service. Juliana Ranches, an OSU Extension Service beef specialist, describes a rancher with cattle experiencing “running rose, running eyes and very bad discharge.”

Ranches has teamed up with Jenifer Cruickshank, OSU Extension’s statewide dairy specialist, to study the effects of smoke exposure on cows. “We hypothesize that by inhaling the smoke, their lungs are drying and that leads to bacterial development which gets them sick,” Ranches said.

Exposure can happen naturally – observing cows exposed to smoke during a regular fire season – or exposure can happen artificially, when researchers place cattle in an enclosed environment with a set amount of smoke.

Since the exact path and ferocity of wildfires are out of researchers’ hands, Cruickshank explained that natural exposure is a tricky research method. Cruickshank is conducting a study with the University of Idaho that compares a herd in Corvallis with a herd in Moscow, Ida.

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“The design was predicated on the assumption that Moscow would get some smoke and Corvallis would not,” Cruickshank said. While this is a fair assumption based on weather patterns in the two areas, it ultimately amounts to a “gamble,” she added.

Moscow did end up getting smoke, but it was mild, and the results were less robust than the researchers had hoped.

For the project Ranches spearheaded, eight heifers were exposed to smoke where air quality was considered unhealthy – at the “purple level,” according to the Air Quality Index (AQI) – in an enclosed barn for a week. The researchers used camera feeds to continuously monitor the animals.

During and after both projects, researchers tested health metrics in the cattle such as blood samples, lung ultrasounds and analysis of immune function.

Cruickshank and Ranches cautioned that that the research is still in the early stages.

“We're definitely in the place where we have lots more questions than answers,” Cruickshank noted. “If we have a better understanding of what the effects of smoke exposure are, that can point us in the direction of what might be good interventions.”

Smoke-induced stress?

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Both studies aren’t just measuring the effects of smoke; they are also testing for stress markers, according to the OSU Extension news release. Preliminary results show increases in cortisol levels and inflammation, in addition to an immune response.

“It’s very stressful for those animals too,” Ranches said. “Maybe we cannot prevent the fires, but we can minimize things that would make them more stressful.”

Ranches and Cruickshank recommend that, when cattle are exposed to wildfire smoke, producers minimize other stressful events like weaning or vaccination. “Everything we can do to minimize that stress is valuable,” Ranches said.

Cruickshank added that waiting until air quality is better reduces “that layering of stressors.”

Next season, Ranches will provide some of the cattle in her experiment with a solution designed to help reduce water loss and improve hydration. Cruickshank and Ranches will communicate the efficacy of management options as they are confirmed through research, OSU said.

In the meantime, the best management technique ranchers can do to protect their cattle is to have a strong evacuation plan in place, the news release noted.

“Producers have lost animals,” Ranches said. “They lost property, pasture and everything. It’s a major loss.”

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Some ranchers credit virtual fencing, which allows them to use GPS collars to move their animals, as the only reason their cattle survived.

“Hopefully they will never have to worry about it, and they will never have to evacuate, but if they do, I would love for them to be ready,” Ranches said.