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Home / Equine Research Bank / Equine Vet J / Assessment of tree-associated atypical myopathy risk factors...
Equine veterinary journal2025; doi: 10.1111/evj.14475

Assessment of tree-associated atypical myopathy risk factors in Acer pseudoplatanus (sycamore) seeds and leaves.

Abstract: Sycamore tree-derived hypoglycin A (HGA) toxin causes atypical myopathy (AM), an acute, equine pasture-associated rhabdomyolysis but incidence fluctuates. Objective: Investigate whether tree or environmental factors influence HGA concentration in sycamore material and are associated with AM relative risk. Methods: Retrospective and experimental prospective study. Methods: UK sycamore population, seed production and AM incidence data were obtained. HGA concentration was measured in seeds from trees from 10 different central UK locations. The effect of tar spot infection, seed maturity, tree trunk girth, location (urban/countryside), AM cases within 130 m, soil type, facing direction of seeds on the tree and year on seed HGA concentration was examined. HGA concentration was compared in whole and homogenated seeds stored in different ways. Results: HGA concentration in sycamore seeds was not associated with tree tar spot infection, location, trunk girth, seed weight or branch-facing direction but HGA concentration in sycamore seeds varied significantly and in parallel year on year in the same trees. Trees in the same vicinity tended to have similar HGA concentrations in their seeds when compared with those from farther afield. Seed production estimates were positively correlated with regional AM case incidence (τb = 0.3; p = 0.007). HGA sycamore seed concentration remained stable as seeds matured, but HGA declined in leaves as they wilted in autumn. Warmer and wet storage resulted in higher HGA concentrations in seed homogenates but not in whole seeds. HGA was detected in water containing sycamore seeds for 48 h. Conclusions: Lack of accurate weather data; sampling restricted to central England. Conclusions: Tree factors that were investigated did not affect HGA concentration in sycamore seeds but HGA concentrations varied year on year. AM incidence is related to seed production; conditions that mimic browsing and ingestion increased seed HGA concentration. HGA toxicity could occur from contaminated water sources.
© 2025 The Author(s). Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
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Publication Date: 2025-01-25 PubMed ID: 39865342DOI: 10.1111/evj.14475Google Scholar: Lookup
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Summary

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The study investigates the factors influencing the production of hypoglycin A (HGA) toxin in sycamore trees, which in turn is associated with an equine disease called atypical myopathy. The research found that yearly variations in the concentrations of HGA were evident in the sycamore seeds but were not influenced by many previously suspected factors including tree characteristics or location.

Research Objective and Methodology

  • This research aimed to understand whether characteristics of the sycamore trees or their environment influenced the concentration of hypoglycin A (HGA) toxin in the trees’ materials. It’s essential because HGA has been identified as a causing factor of Atypical Myopathy (AM), a lethal condition in horses that causes muscle degeneration.
  • The study design involves a combination of retrospective and experimental prospective methodologies. Data about the UK sycamore population, its seed production, and the incidences of AM were acquired. The HGA concentration in seeds from sycamore trees positioned at ten different central UK locations was measured.

Data Analysis and Findings

  • The study examined a range of factors that could potentially influence the concentration of HGA in the sycamore seeds including seed maturity, the presence of tar spot infection on the tree, the thickness of the tree trunk, its location (urban or rural), the proximity of AM cases within a 130 m radius, soil type, the direction the seeds on the tree were facing, and differences from one year to another.
  • Results showed no evident association between the levels of HGA in sycamore seeds and factors such as tar spot infection, location, trunk girth, seed weight, or branch-facing direction. In contrast, the concentration of HGA in sycamore seeds saw significant variations from year to year, and trees located in close proximity tended to have parallel levels of HGA in their seeds.
  • There was further analysis to identify any relationship between seed production and AM occurrences; the findings indicated a positive correlation with an increase in seed production being linked to a rise in regional incidences of AM.
  • Further experimental conclusions were that HGA concentrations remained stable as seeds matured but diminished in leaves as they wilted in the autumn. It was also discovered that conditions that mimic browsing and ingestion, such as warmer and wet storage, led to heightened HGA concentrations within seed homogenates, although this was not evident in whole seeds.

Study Limitations and Conclusions

  • The limitations of the study were primarily linked to the lack of accurate weather data during the research period and the spatial restriction of the sampling to central England.
  • The results indicate that factors relating to the tree itself did not significantly impact HGA concentration within sycamore seeds, but there was a significant variation in HGA concentrations from year to year. Moreover, the incidence of AM was found to be related to seed production, and conditions resembling browsing and ingestion increased seed HGA concentration. The research also highlighted the potential risk of HGA contamination from water sources carrying sycamore seeds.

Cite This Article

APA
González-Medina S, Hyde C, Chang YM, Piercy RJ. (2025). Assessment of tree-associated atypical myopathy risk factors in Acer pseudoplatanus (sycamore) seeds and leaves. Equine Vet J. https://doi.org/10.1111/evj.14475

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English

Researcher Affiliations

González-Medina, Sonia
  • Comparative Neuromuscular Diseases Laboratory, Department of Clinical Science and Services, The Royal Veterinary College, London, UK.
Hyde, Carolyn
  • Bio-Analysis Centre, London, UK.
Chang, Yu-Mei
  • Comparative Biomedical Sciences, The Royal Veterinary College, London, UK.
Piercy, Richard J
  • Comparative Neuromuscular Diseases Laboratory, Department of Clinical Science and Services, The Royal Veterinary College, London, UK.

Grant Funding

  • G6015 / Horse Trust
  • Royal Veterinary College's Animal Care Trust

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