Atypical myopathy in grazing horses

Fohlen mit atypischer Weidemyopathie  Bergahorn  Fohlen mit atypischer Weidemyopathie

Atypical myopathy in grazing horses is a muscular disease which proceeds dramatically, leading to death through respiratory and cardiac arrest within only 12 – 72 hours in most cases.

Horses, which are affected by this deadly disease show a stiff gait, sweating, muscle tremor and muscle weakness  and will eventually be totally blocked in the final stage. They perish from a generalized muscular destruction, which also affects cardiac and respiratory muscles. The urine of the affected horses is almost black, as they pass myoglobin through the kidneys, a muscle colorant, which is released with muscular destruction.

In spite of intensive European wide research, the cause of the disease could not be discovered so far. This means that there is still no target-oriented therapy or prophylaxis. At present, ISME is researching if special poisonous substances from bacteria in the ground could be responsible for the disease (see publication list). For this purpose, blood, feces and muscle samples of diseased horses are being examined. These samples could be collected with the help of affected horse owners and treating veterinarians.

Weide mit Bergahorn

A toxin in the seed of the Sycamore maple could possibly be the cause for atypical myopathy in grazing horses in Europe. We visited these pastures known to have had affected horses together with Prof. Valberg from the University of Minnesota, documented the occurrence of Sycamore maples and took samples of maple seeds for analysis. We are currently waiting for the results.

As we are planning further tests, we are still dependent on this type of co-operation. As soon as new cases show up, we would like to ask you to get in touch with us anytime by phone (+41 31 631 22 43) or by email (lucia.unger@vetsuisse.unibe.ch).  For this research project, we need to collect as much detailed information on outbreaks as we can in order to help avoid further cases and to be able to diagnose the disease more efficiently. Only when the cause is found, can the disease be controlled.

List of publications:

  • Unger-Torroledo L, Straub R, Lehmann A, Graber F, Stahl C, Frey J, Gerber V, Hoppeler H, Baum O, Lethal toxin of Clostridium sordellii is associated with fatal equine atypical myopathy. Veterinary Microbiology 2010, 144(3-4): 487-492.
  • Van Gahlen G, Amory H, Busschers E, Cassart D, De Bruijn M, Gerber V, Keen J, Lefere L, Pitel CM, Marr C, Müller JMV, Pineau X, Saegerman C, Sandersen C, Serteyn D, Torfs S, Unger L, Verwilghen D, Votion DM, 2010, European outbreak of atypical myopathy in the autumn 2009. Journal of Veterinary Emergency and Critical Care, 20(5): 528-532
  • Unger L, Gerber V, 2011, Search for the cause of Equine Atypical Myopathy, Equine Disease Quarterly, Vol 20, No 2
  • Van Galen, G, Marcillaud Pitel, C, Saegermann C, Patarin F, Amory, H, Baily, JD, Cassart, D, Gerber, V, Hahn, C, Harris, P, Keen, JA, Kirschvink, N, Lefere, L, McGorum, B, Muller, JMV, Picavet, MTJE, Piercy, RJ, Roscher, K, Serteyn, D, Unger, L, van der Kolk, JH, van Loon, G, Verwilghen, D, Westermann, CM, Votion, DM, 2012, European outbreaks of atypical myopathy in grazing equids (2006-2009): Spatiotemporal distribution, history and clinical features. Equine Veterinary Journal, Vol 44(5): 614-620.
  • Van Galen, Saegermann C, G, Marcillaud Pitel, C, Patarin F, Amory, H, Baily, JD, Cassart, D, Gerber, V, Hahn, C, Harris, P, Keen, JA, Kirschvink, N, Lefere, L, McGorum, B, Muller, JMV, Picavet, MTJE, Piercy, RJ, Roscher, K, Serteyn, D, Unger, L, van der Kolk, JH, van Loon, G, Verwilghen, D, Westermann, CM, Votion, DM, 2012. European outbreaks of atypical myopathy in grazing horses (2006-2009): Determination of indicators for risk and prognostic factors. Equine Veterinary Journal, Vol 44(5): 621-625.