Atypical Equine Myopathy: Vigilance Is Key This Spring

In light of the sharp increase in cases of atypical myopathy in the United Kingdom last fall, the British Equine Veterinary Association (BEVA) is urging equine veterinarians to remain vigilant. There is indeed concern that there will be a resurgence of outbreaks this spring. France, the second-most affected country, will likely not be spared.

  Atypical equine myopathy is rampant in the United Kingdom and Northern Europe. This fatal muscle disease affects horses in pastures. To date, the cause of the infection has been attributed to the action of a toxin, hypoglycin A, found in the seedlings that grow from the seeds of certain trees, such as the sycamore maple (Acer pseudoplatanus ) or the box elder (Acer negundo ). Early diagnosis is essential, as the prognosis is often poor, with survival rates of less than 25%. There were five times as many cases of atypical myopathy in the fall of 2014 as in the previous year across the Channel. However, the disease tends to intensify during the spring following a fall with a particularly high number of cases, likely due to the resumption of germination. Symptoms of atypical myopathy include muscle weakness or stiffness, signs of colic, labored breathing, dark urine, prostration, and sometimes sudden death. The disease often takes on an epizootic form. Confirmation of the diagnosis requires a blood or urine test. P For horse owners, prevention involves several precautionary measures, such as carefully checking pastures in the spring for seeds, limiting grazing if these seeds are present and allowing only well-fed animals to graze, providing supplemental feed in the pasture so they are less tempted to ingest seeds, avoiding leaving damp hay to rot on the ground, and fencing off affected areas. It’s important to note that even a pasture without maple trees can contain seeds spread by wind or floodwaters during heavy rains. D^r . Dominique Votion, of the Faculty of Veterinary Medicine in Liège (Belgium), has been studying this disease for many years. To maximize the chances of prevention, the Belgian university has developed a Europe-wide epidemiological surveillance network, the Atypical Myopathy Alert Group (AMAG)*. Since 2006, it has enabled the recording of all European cases. Currently, this alert group is composed of equine veterinarians located around the world, national epidemiological networks (such as Respe in France), universities, and research centers. The goal is to exchange information on outbreaks of atypical myopathy and to conduct collaborative research. Thus, in response to the number of cases reported to this network in 2014 by the United Kingdom (97) and Ireland (28), the University of Liège (ULg), in collaboration with the Irish Equine Center and the Animal Health Trust , launched a new study examining the geographic distribution and clinical characteristics of this disease across the Channel. A better understanding of its specific etiology should help advance strategies to combat the epizootic disease. France, with 48 cases recorded by AMAG in 2014, is among the most affected countries, behind the United Kingdom but ahead of Ireland. Next come Belgium (29 cases) and, to a lesser extent, Germany (6 cases) and the Netherlands (3 cases). The latest report from the French Equine Pathology Epidemiological Surveillance Network (RESPE) lists 27 suspected cases of atypical myopathy reported by sentinel veterinarians as of December 19, 2014:

• 5 cases in Calvados, 5 in Manche;
• 4 cases in Orne;
• 3 cases in Seine-Maritime;
• 2 cases in Côtes-d’Armor, 2 in Oise;
• 1 case in Finistère, 1 in Marne, 1 in Meurthe-et-Moselle, 1 in Pas-de-Calais, 1 in Bas-Rhin, and 1 in Seine-et-Marne.

  * Through the website www.myopathie-atypique.be, veterinarians encountering cases of atypical myopathy are encouraged to report them online (http://labos.ulg.ac.be/myopathie-atypique/veterinaire/formulaire-veterinaire)