Common North American Poisonous Plants that Contaminate Hay

The list as presented is not very helpful as symptoms of these common poisonings are not given. If you are suffering from a sick horse that may have been poisoned best is to find the article on the symptoms you are experiencing and diagnostic information will be available there. Nonetheless, this list may be a starting point for pasture and hay field management.

Plants that Contaminate Feed and Forage and Poison Horses: Equine Toxicology
Vet Clin North Am Equine Pract. 2023 Dec 6:S0749-0739(23)00075-5. doi: 10.1016/j.cveq.2023.11.003.
Authors
Bryan L Stegelmeier 1 , T Zane Davis 2
Affiliations

1 USDA/ARS Poisonous Plant Research Laboratory, Logan UT 84341, USA. Electronic address: Bryan.Stegelmeier@USDA.GOV.
2 USDA/ARS Poisonous Plant Research Laboratory, Logan UT 84341, USA.

PMID: 38061966
DOI: 10.1016/j.cveq.2023.11.003

Abstract

Many toxic plants are unpalatable to horses and are not eaten when alternative forage is available. However, when such plants contaminate prepared or baled feed and forage, herd competition and improved palatability can alter acceptance and thereby cause equine plant poisonings. Dehydropyrrolizidine alkaloid-containing plants; cocklebur; Salvia reflexa; kleingrass, switchgrass, and other saponin-containing grasses; jimson weed, black henbane, and other tropane alkaloid-containing plants; lantana; Cassia spp and other myotoxic plants; castor bean; cyanogenic glycoside-containing plants; thiaminase-containing plants; and hoary alyssum are among those that most commonly poison horses in North America via contaminated feed or forage.

Keywords: Diagnosis; Equine; Poisoning; Poisonous plants; Range and pasture; Treatment.