Deer and livestock
Odocoileus, Equus, Ovis
The animals that leave milkweed alone, and the circumstances in which they do not.
What it does on milkweed
Deer, cattle, horses and sheep avoid living milkweed because it is bitter and makes them ill. That makes milkweed one of the more reliably deer-resistant perennials available. The danger is dried milkweed in baled hay, where the bitterness fades but the toxins do not, and an animal with nothing else to eat will take it. The narrow-leaved western species, particularly whorled and western whorled milkweed, are the most dangerous per mouthful.
How to recognize it
Not applicable, but the sign is: an ungrazed milkweed standing in a closely browsed pasture.
Where and when
Nationwide. Livestock poisoning cases concentrate in the arid West, where forage is thin. Most often seen January to December.
Should you do anything about it?
Plant it freely in a deer-browsed garden. Keep it out of hay meadows, and out of paddocks where forage is short.
Deer and livestock: common questions
Is milkweed deer resistant?
Yes, reliably. Cardenolides in the sap make it bitter and toxic, and deer leave it standing even where they have browsed everything around it.
Is milkweed dangerous to horses?
Living plants are avoided. The risk is dried milkweed in hay, where the toxins persist but the taste does not. The narrow-leaved whorled species are the most toxic.
Cite this page
This page is licensed CC BY 4.0. Quote it, adapt it and reuse it, including commercially, as long as you credit Milkweed USA and link back.
Milkweed USA. (2026). Deer and livestock (Odocoileus, Equus, Ovis). Retrieved DATE, from https://milkweedusa.com/wildlife/deer-and-livestock/
"Deer and livestock (Odocoileus, Equus, Ovis)." Milkweed USA, 2026, https://milkweedusa.com/wildlife/deer-and-livestock/. Accessed DATE.
Milkweed USA. "Deer and livestock (Odocoileus, Equus, Ovis)." Last modified 2026-08-01. Accessed DATE. https://milkweedusa.com/wildlife/deer-and-livestock/.
@misc{milkweedusa_wildlifedeerandlivestock,
title = {Deer and livestock (Odocoileus, Equus, Ovis)},
author = {{Milkweed USA}},
year = {2026},
url = {https://milkweedusa.com/wildlife/deer-and-livestock/},
note = {Accessed DATE}
}