Assessment of tree-associated atypical myopathy risk factors in Acer pseudoplatanus (sycamore) seeds and leaves.
Authors: González-Medina, Hyde, Chang, Piercy
Journal: Equine veterinary journal
Summary
# Atypical Myopathy and Sycamore Trees: What Influences Toxin Levels? González-Medina and colleagues investigated why atypical myopathy (AM) incidence fluctuates seasonally and geographically in the UK, focusing on hypoglycin A (HGA)—the toxic compound in sycamore seeds responsible for this acute pasture-associated rhabdomyolysis. Combining retrospective AM case data with experimental analysis of seed and leaf samples from ten central English locations, the team measured HGA concentrations under various conditions and tested whether tree characteristics (tar spot infection, trunk girth, location type) or environmental factors influenced toxin production. Contrary to expectations, individual tree factors did not predict HGA levels in seeds, yet the same trees consistently produced seeds with similar HGA concentrations year on year, and trees in close proximity showed comparable toxin profiles—suggesting environmental or genetic clustering effects. Critically, regional seed production estimates correlated significantly with AM case incidence (τb = 0.3; p = 0.007), and while HGA remained stable throughout seed maturation, it declined as leaves wilted in autumn; storage conditions mimicking digestive processes (warm, wet environments) increased HGA concentrations in seed homogenates, and HGA persisted in water for 48 hours. For practitioners, these findings reinforce that AM risk is intimately linked to mast year intensity and highlight an underappreciated hazard—contaminated water sources near sycamore trees may pose a toxicity risk independent of direct leaf or seed ingestion.
Read the full abstract on PubMed
Practical Takeaways
- •Monitor sycamore seed production intensity as a predictor of AM risk in your region—higher seed years correlate with increased case incidence
- •Recognize that AM risk fluctuates year-on-year even from the same pasture trees; weather and storage conditions (wet, warm) may concentrate toxin in seeds and water sources
- •Consider water sources near sycamore trees as a potential AM exposure route, particularly when seeds are present or decomposing
Key Findings
- •HGA concentration in sycamore seeds varied significantly year-on-year in the same trees, independent of tar spot infection, location, trunk girth, or seed weight
- •Seed production estimates were positively correlated with regional AM case incidence (τb = 0.3; p = 0.007)
- •HGA remained stable in maturing seeds but declined in wilting autumn leaves; warmer and wet storage conditions increased HGA concentration in seed homogenates
- •HGA was detected in water containing sycamore seeds for 48 hours, suggesting contaminated water sources as a potential toxicity route