Loco Weed – Toxic Plant of the Week

Loco Weed

Image from jkirkhart35

Welcome to the latest edition of the a-z of plants that have it in for horses. Today’s plant is one that many will know & love, it is beautiful, delicate & smells divine. Loco Weed may look innocent & smell sweet, but don’t get too close, it is deadly toxic – even to humans.

A Little About Loco Weed

Astragalus & Oxytropis species are also Crazy Weed & Loco Weed. There are two different types of this plant.

Astragalus is an annual with dark purple stems. Leaves are hairy & grow in leaflets. Flowers are purple & grow in clusters at the end of branches.

Oxytropis is an annual legume with leaves that are covered in fine, white hairs. Flowers are white & grow in spikes on a leafless stalk.

How Dangerous Is It?

This plant is unpalatable & generally only a concern during drought conditions. While it is not fatal, this plant is worth noting. Once an animal starts eating it, they can become addicted to it & will eat nothing else. Loco Weed contains Swainsonine which disrupts the function of brain cells, A condition called “locoism”, the effects of which are irreversible.

All parts of this plant are toxic (both fresh & dried) to equines.


Loco Weed

Image from Jeantosti

Loco Weed

Image from Matt Lavin

What To Look For

You know your animal the best, so you should know when something is amiss. Loco Weed toxicity symptoms occur after constant ingestion & include strange behavior, low sensory & motor nerve function, depression of the central nervous system, dull eyes, nervousness, progressive loss of coordination, lack of appetite/ thirst, fetal death, birth defects, excitability & confusion.

Learn More

Be sure to check out the Loco Weed page to learn more about the plant & while you are at it why not check out more toxic plants?

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*It should be noted that we’re not veterinarians. This information is written specifically for horses & should be used for reference purposes only. If you think your horse has eaten something toxic call your vet right away.