lo·​co·​ism ˈlō-(ˌ)kō-ˌi-zəm How to pronounce locoism (audio)
: a neurological disease usually of livestock (such as horses, cattle, and sheep) that is caused by chronic ingestion of large amounts of locoweeds and that is characterized by lethargy, erratic behavior, weight loss, incoordination, and ultimately paralysis or death
Locoism is diagnosed primarily through displayed symptoms and positive identification of toxin-producing locoweeds grazed by the animals. … There is no treatment for locoweed poisoning beyond removing affected livestock from access. Animals that are severely affected may never recover fully and continue to exhibit residual behavior patterns …Ashley Wright

Word History

First Known Use

1888, in the meaning defined above

Time Traveler
The first known use of locoism was in 1888

Dictionary Entries Near locoism

Cite this Entry

“Locoism.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/locoism. Accessed 25 May. 2024.

Medical Definition


lo·​co·​ism ˈlō-kō-ˌiz-əm How to pronounce locoism (audio)
: a neurological disease usually of livestock (such as horses, cattle, and sheep) caused by chronic ingestion of large quantities of locoweeds and that is characterized by motor and sensory nerve damage resulting in peculiarities of gait, impairment of vision, lassitude or extreme excitement, emaciation, and ultimately paralysis and death if not controlled
Although many studies have reported that … locoweed could poison animals, many clinical symptoms will resolve if … exposure is discontinued. However, many neurologic lesions are permanent, causing permanent functional problems in the corresponding organs of poisoned animals or even death. For this reason, an early diagnosis of locoism is one of the most important measures to reduce economic losses to the livestock industry.Jifeng Jiao et al., Chemico-Biological Interactions
: any of several intoxications of domestic animals (such as selenosis) that are sometimes mistaken for locoweed poisoning
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