Poison Plants: Cyanide Poisoning in Goats
Learn what plants contain cyanogenic glycosides
Reading Time: 7 minutes
Cyanide poisoning (previously called prussic acid poisoning) in goats is caused when they eat plants that contain cyanogenic glycosides. The glycosides contained in the cells of plants are turned into cyanide when the cells are ruptured. Goats and other ruminants are more susceptible to such poisoning than other animals because of the bacteria contained in the rumen and the intensive chewing of their food, which releases more cyanide.
When goats eat these plants, hydrogen cyanide is released in the rumen and enters the bloodstream, preventing the release of oxygen by the hemoglobin. Some of the cyanide can be detoxified, but if a large quantity is involved, it can kill the animal within an hour or two. Once goats start to show symptoms — breathing hard, foaming at the mouth, dilated pupils, shaking, and difficulty walking — they are unlikely to survive. The most telling sign is bright red membranes, such as the gums and eyelids. Treatment for cyanide poisoning requires veterinary care.
The amount of cyanide in a plant varies, based on species and environmental conditions such as weather, fertility of soil, and stage of growth. (See “How Weather Impacts Forages,” Goat Journal, March 2025) Goats that are used to eating the plants and those on high-grain rations (which leads to a more acidic rumen) are less likely to be poisoned. In cases of chronic exposure to low levels of cyanide, goats may fail to gain weight, show behavioral changes, or develop a goiter when low iodine intake also occurs. This has been noted in lambs, which can also have skeletal defects.
In some cases of acute poisoning, a rumenotomy or necropsy helps identify the cause of death by cyanide through analysis of the leaves found in the rumen.
Goats appear to be the most susceptible of all ruminants, with less than a milligram per pound of body weight being a lethal dose. However, at lower doses, they can also experience chronic poisoning, which can cause brain lesions and neurological symptoms, as well as depressed growth.
The plants most likely to cause cyanide poisoning in animals in the U.S. include:
California Holly
California Holly (Heteromeles arbutifolia): Also known as Christmas berry or toyon, this evergreen shrub in the rose family is native to California. Both the leaves and bright red berries contain cyanogenic glycosides. The cyanide content is highest in winter and spring. The toxin in the berries is neutralized on cooking or fermentation. In one report, goats that ate clippings were poisoned, with three dying within four hours and seven becoming very ill, with accelerated heart rate, pale membranes, and hemorrhages in the lungs and heart. In some, the kidneys and the gastrointestinal tract were also affected.
Elderberry
Elderberry (Sambucus nigra): The elderberry, a member of the honeysuckle family, is a woody shrub that can grow as tall as 10 feet. The plant sends out underground runners to create colonies. It has white flowers with five petals and dark purple berries. As in California holly, the berries are poisonous, containing the glycoside, sambunigrin. The glycosides can be neutralized by cooking or fermentation, and are often used in wine, jam, and medicinal syrups.
Johnson and Sudan Grasses
Johnson and Sudan Grasses (Sorghum spp.): These broad-leafed grasses, used as forage crops, are found mainly east and south of the Rocky Mountains. Johnson grass is a perennial, while Sudan grass is an annual. They contain the cyanogenic glycoside, dhurrin. They are the most common cause of cyanide poisoning in sheep and cattle, mostly when fertilized with a high level of nitrogen, frost-damaged, or when the plants begin to grow quickly after a drought. The leaves are the most poisonous part. Goat keepers can prevent poisoning by feeding cyanide-free Sudan grass hybrids, avoiding grazing during fast growth or regrowth of the plants, and feeding cured grasses.
Cherry
Western chokecherry, black cherry, Carolina laurel cherry, peach, English laurel cherry, and fire cherry (Prunus spp.): These plants in the rose family are a common cause of poisoning in goats, although it’s not known which are the most likely culprits. A Guide to Plant Poisoning of Animals in North America focuses on the western chokecherry (Prunus virginiana var. melanocarpa). This tree or shrub can grow up to 16 feet tall and sports showy white flowers in the spring. Its dark-purple fruit is edible; however, the leaves, bark, seeds, and shoots are toxic, containing the cyanogenic glycosides, amygdalin and prunasin.
The leaves are the most toxic part of the plant, particularly after they have wilted. A goat that eats 25% of its body weight in fresh leaveswill likely die. Bordering your pasture with these trees is risky for goats and should be avoided.
Western Serviceberry
Western Serviceberry (Amelanchier alnifolia): Also known as Saskatoonberry or Juneberry, this shrub grows in altitudes over 5000 feet in North America. It can grow up to 13 feet tall, and each flower sports five white petals. The dark-colored berries are edible. Like the cherry plants above, it contains cyanogenic glycoside prunasin. Goats will encounter a problem only when excessively eating the plant after a drought or during times of accelerated growth.
Other Plants
Other plants that may contain cyanogenic glycosides but are less likely to have been reported for poisoning in goats include:
- Birdsfoot trefoil (Lotus corniculatus): It can contain lotaustralin, although some populations are devoid of it or have been bred for low cyanide. Tannins in the plant are known to help prevent parasites.
- Wild blue flax (Linum lewsii): It also contains varying amounts of lotaustralin, mostly in tops and seeds. If linseed meal from the plant is fed to livestock, it must be boiled to prevent poisoning.
- Mountain mahogany (Cercocarpus montanus): Ruminants generally avoid this plant.
- Catclaw Acacia (Acacia greggii/Senegalia greggii):This legume contains prunasin, as well as other poisonous substances. Generally browsed when other food is scarce.
- Poison suckleya (Suckleya suckleyana): This plant, which grows near ponds and other wet areas, can vary in the amount of glycosides present. It’s more often eaten during drought conditions, when goats can’t find preferred food.
Be aware of what kinds of plants are near or in your pasture. If you take your goats browsing outside of their pasture or cut browse for them, learn about which leaves and berries they should avoid. For example, where I live, one side of my property is bordered with elderberry and chokecherry. Through researching plants before giving them to our goats, we’ve learned to avoid feeding these leaves to them when trimming and to keep them away from the dried leaves in the fall.
Ask questions and become an informed buyer of hay to avoid purchasing anything that might put your goats at risk. Be especially wary after a drought.
Don’t miss the other articles in this series:
- Plants Poisonous to Goats: Introduction
- Poisonous Plants to Goats: Alkaloids
- Plant Poisoning in Goats: Cardiac Glycosides
Cheryl K. Smith has raised miniature dairy goats in the coast range of Oregon since 1998. She is an editor for Ogden Publications and the author of Goat Health Care (karmadillo Press), Raising Goats for Dummies (Wiley), Goat Midwifery (karmadillo Press), and two books in the Hidden Creek Farm cozy mysteries series, Shed Boy, and Gone Goat.
References:
- Gensa, U. 2019. “Review on Cyanide Poisoning in Ruminants.” J Biol, Agriculture and Healthcare 9(6): 1-12. doi:10.7176/JBAH.
- Knight, Anthony P, and Richard G. Walter. 2001. A Guide to Plant Poisoning of Animals in North America. Jackson, Wyoming: Teton NewMedia.
- Knight, Anthony P. 2014. “Plant Poisoning of Small Ruminants.” https://avmaspeakers.eventkaddy.net/event_data/28/session_files_published/2014_16104.pdf
- Radi, ZA, EL Styer, and LJ Thompson. 2004. “Prunus Spp. Intoxication in Ruminants: A Case in a Goat and Diagnosis by Identification of Leaf Fragments in Rumen Contents.” J Vet Diagn Invest 16(6): 593–99. doi:10.1177/104063870401600620.
- Smith, R, et al. “Cyanide Poisoning in Ruminants.” https://ruminant.ca.uky.edu/files/cyanide-final.pdf
- Tegzes, JH, B. Puschner, and LA Melton. 2003. “Cyanide Toxicosis in Goats after Ingestion of California Holly.” J Vet Diagn Invest 15(5): 478–80. doi:10.1177/104063870301500515.
- www.ukvetlivestock.com/content/clinical/plant-poisoning-in-goats/
- https://ruminant.ca.uky.edu/files/cyanide-final.pdf
- https://horsedvm.com/poisonous/toyon
Originally published in the September 1, 2025 digital issue of Goat Journal.
