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Prevention strategies to reduce the risk of atypical myopathy resulting from sycamore intoxication

Author(s):
Votion D.M.
In: EEHNC - Virtual Congress - 2021 by European Equine Health and Nutrition Congress
Updated:
FEB 09, 2023
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Take home messages

Equine atypical myopathy (AM) is a severe intoxication of grazing equids resulting from the ingestion of samaras or seedlings of trees from the Acer species. The sycamore maple (Acer pseudoplatanus) is involved in European cases whereas the box elder (Acer negundo) is recognized as the cause of this seasonal pasture myopathy in the Unites States of America. Equids horses become intoxicated after eating the toxic materials that contain at least two toxins. This intoxication is associated to a high mortality rate. Currently, the therapy is mainly symptomatic and the mortality rate average 74%. As there is no specific treatment for AM yet, prevention is the key. By reviewing the most recent literature and by analysing epidemiological data gathered since 2006 by the Atypical Myopathy Alert Group” (AMAG; ULiège, Belgium) and the Réseau d’Épidémio-Surveillance en Pathologie Équine (RESPE; France).

We can identify five levers of action to reduce the risk of AM resulting from sycamore intoxication:

  • Prevent (any) access to the cause: if feasible, prevent access to sycamore samaras & seedlings but do not forget other potential toxic Acer species
  • Avoid additional sources of intoxication: during at risk seasons, avoid any additional sources of intoxication such as flowers of sycamore maple tree, their leaves, water in contact with seedlings, forages contaminated with samaras and/ or seedlings etc. Do not forget that toxins transfer to milk that may represent a risk for newborn and unweaned foals. Prevent access to rivers and the possibility of drinking free standing water from the ground during the at risk seasons
  • Identify the risks associated with your pasture: all pastures with a sycamore tree in the vicinity must be considered at risk. Avoid certain practises that may increase the risk such as harrowing and beware of the risk associated to contaminated forages even if they have been stored for a long period. All equids of any age are at risk but ruminants may also be intoxicated.
  • Favour/ create low‐risk meadows for pasturing during autumn and spring: avoid overgrazing and minimise toxins consumption by ensuring lush pasture and/ or supplementary feeding throughout the outbreak seasons. Visit your pasture in autumn after stormy weather has dispersed sycamore samaras and fence off these areas temporarily to prevent access to toxic areas. Destroy young seedlings as soon as possible. Do not forget they remain toxic until full decomposition. Collect samaras if feasible. Consider the trimming of maple trees in close proximity to avoid flowers and fruits production.
  • Take specific measures during alert: AM occurs seasonally with outbreaks starting in autumn that may continue in early winter. Spring outbreaks usually cease before summer. Starting and ceasing dates of autumnal and spring outbreaks vary between years, probably depending on climatic conditions. The majority (94%) of “spring” and “autumnal” cases occurred between 1 March and the 31 May and between the 1 October up to the 31 December, respectively. During the risky periods, pasturing time should be modulated according to weather conditions. Remove horses from pastures when you receive alert messages (resulting from cases‘ declaration to the surveillance networks) or at least, minimise pasture time to less than 6 hours a day especially when stormy weather conditions have been forecast including in spring when there are flowering trees surrounding the pasture. Provide supplementary feeding but ensure forages are toxin-free. Also, it is advised to supply a salt block enriched in selenium and provide drinking water from the distribution network.

Atypical myopathy is an emerging intoxication that will definitely be part of the life of equine managers and practitioners. There are no easy solutions, only an adapted management of the pastures will allow limiting the risks.

Acknowledgments

The authors thank all communicating veterinarians and owners of affected horses for their collaboration. Over the years, our studies were supported by the la Wallonie agriculture SPW (Service public de Wallonie; Belgique), l’“Institut français du cheval et de l’équitation (Ifce)” of France and by “Les Fonds Spéciaux pour la Recherche (FSR)” of Liege University (Belgium).

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How to reference this publication (Harvard system)?

Votion, D. (2023) “Prevention strategies to reduce the risk of atypical myopathy resulting from sycamore intoxication”, EEHNC - Virtual Congress - 2021. Available at: https://www.ivis.org/library/eehnc/eehnc-virtual-congress-2021/prevention-strategies-to-reduce-risk-of-atypical-myopathy-resulting-from-sycamore-intoxication (Accessed: 03 June 2023).

Author(s)

  • Votion D

    Votion D.M.

    Assistant Professor
    DVM PhD
    Laboratory for Functional Investigation, Faculty of Veterinary Medicine, University of Liège
    Read more about this author

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