Horses fed hay contaminated with caley pea (Lathyrus hirsutus L.) plants, seeds, or seed pods could be at risk for intoxication, researchers have determined.

The caley pea is present in many of the lower 48 United States, but is most commonly identified in Texas, Oklahoma, New Mexico, the Pacific Northwest, and Eastern states such as Florida and Virginia.

“Because it could be present in hay produced in these regions (and shipped to other regions), any horse fed imported hay from these regions could also be at risk,” said researcher Todd Holbrook, DVM, Dipl. ACVIM, ACVSMR, professor and the June Jacobs Endowed Chair in Equine Medicine at the Oklahoma State University Center for Veterinary Health Sciences.

Holbrook said horses can exhibit signs of intoxication as soon as a few days after eating the caley pea plant or its seeds, but residual signs can persist for weeks or months. Acute signs can include, but are not limited to, a reluctant, short-strided gait with the hind limbs placed farther forward than normal. Horses with severe forelimb laminitis often move similarly; however, in Holbrook’s recent study, the horses did not experience foot pain