Plants Causing Toxic Myopathies

The above article on equine myopathies covers these plants in more detail, but this serves as a reminder of the danger.
DrO

Plants Causing Toxic Myopathies
Vet Clin North Am Equine Pract. 2023 Dec 26:S0749-0739(23)00073-1. doi: 10.1016/j.cveq.2023.11.001. Online ahead of print.
Authors
Beatrice Sponseller 1 , Tim Evans 2
Affiliations

1 Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, 1809 South Riverside Drive, Ames, IA 50011, USA. Electronic address: beatrice@iastate.edu.
2 Department of Biomedical Sciences, College of Veterinary Medicine and MU Extension, University of Missouri, W226 Veterinary Medicine Building, 1520 East Rollins Street, Columbia, MO 65211, USA.

PMID: 38151404
DOI: 10.1016/j.cveq.2023.11.001

Abstract

Boxelder and sycamore maple contain hypoglycin A (HGA), the toxic metabolite of which, MCPA-CoA, inhibits fatty acid β-oxidation, causing seasonal pasture myopathy (SPM) or atypical myopathy (AM), respectively. White snakeroot and rayless goldenrod contain multiple benzofuran ketones (BFKs). The identity/toxicity of BFKs appear variable, possibly involving interactions between toxins/toxic metabolites, but ultimately inhibit cellular energy metabolism. Unthrifty horses grazing sparse pastures during the fall appear predisposed to these plant-associated, frequently fatal, toxic myopathies. Toxidromes are characterized by varying degrees of rhabdomyolysis and cardiac myonecrosis, with plant toxins remaining toxic in hay and being excreted in milk.

Keywords: Benzofuran ketones; Boxelder and sycamore maple; Cardiomyopathy; Hypoglycin A; Rayless goldenrod; Toxic myopathy; Tremetol/tremetone; White snakeroot.