A bit of ear goop can reveal if sheep are eating dangerously poisonous plants.
Earwax from sheep that have eaten death camas contains the plants’ toxins within a few days following the noxious meal, researchers report in the December 2024 Toxicon. The findings add to a growing list of medical insights researchers can glean from swabbing some wax (SN: 2/24/14).
While grazing in pastureland, livestock like cattle and sheep can die from eating poisonous plants. Determining the culprit is a big job, says Stephen Lee, an analytical chemist at the U.S. Department of Agriculture’s Poisonous Plant Research Lab in Logan, Utah. Lab workers might visit the pasture to test plants or analyze blood from living herd members, which requires specialized training and equipment. Lee and his colleagues have been studying earwax as a simpler sample that can indicate if animals are being exposed to fatal forage.
The team focused on death camas (Zigadenus paniculatus, sometimes classified as Toxicoscordion paniculatum), a relative of lilies that grows in much of the western U.S. Livestock that eat enough of the plants suffer from the toxic effects of two compounds, zygacine and zygadenine, which cause mouth frothing, teeth grinding, twitching, stiff-legged walking, vomiting and potentially death, often via heart and respiratory failure. Lee and his team knew from previous studies that there was a death camas dosage that could be given to the sheep to make them sick, but not severely ill to the point of death. So, the researchers dosed sheep with just enough of the toxic compounds by infusing an alfalfa slurry with an extract from death camas. The researchers then took earwax samples every few days for month, starting on day three. They also sampled earwax from sheep that grazed in a pasture chock full of death camas for three days.
The researchers detected the toxins in the earwax of the dosed sheep, with concentrations highest three days after eating the…
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