FIRST CASES OF ATYPICAL MYOPATHY NOTIFIED IN EUROPE & LATEST ADVICE
A group of European vets lead by Dr Dominique Votion at the University of Liege has been studying atypical myopathy (AM) for the past 20 years. This year they published a new paper entitled “Answers to the Frequently Asked Questions Regarding Horse Feeding and Management Practices to Reduce the Risk of Atypical Myopathy” (VOTION et al. 2020). The paper also includes some interesting data on how AM varies in prevalence between countries and also how some years are significantly worse than others
Equine atypical myopathy (AM) is a severe pasture-associated intoxication that may occur in autumn following ingestion of the seeds (samaras, winged seeds or “helicopters”) in the autumn or seedlings when they sprout in the following spring, of trees of the Acer species, most notably Acer pesudoplantus (sycamore Europe, sycamore maple in North America) and Acer negundo (box elder, USA). The clinical signs of AM in horses and ponies are caused by the cyclopropylamino acids, hypoglycin A (HGA) and methylenecyclopropylglycine (MCPG), Both Acer pseudoplatanus and Acer negundo seeds have been found to contain HGA and MCPG.
SYMPTOMS OF ATYPICAL MYOPATHY
- Muscle weakness, soreness or stiffness; horses may struggle to walk, stand or breathe
- Horses appear dull/depressed with head held low
- Muscle tremors
- Colic like symptoms
- Dark brown or dark red urine
- Some horses may develop respiratory symptoms
- Inability to stand
Atypical myopathy has a high mortality rate that varies between countries and years, but typically only 1 in 4 horses that develop it survive. Animals that are rapidly admitted to a veterinary hospital are reported to have a higher chance of survival.
In 2004, an alert group named “Atypical Myopathy Alert Group” (AMAG) was launched to warn horse practitioners and owners of the risk peaks. The alerts are released following case declarations and the AMAG regularly updates its data with the latest number of cases. In light of the high mortality rate and the absence of specific treatment, prevention is the key to avoid intoxication of animals.
The paper by Votion et al. (2020) aims at answering the five most frequently asked questions (FAQs) regarding
- identification of toxic trees
- reduction of risk at the level of (2) pastures
- the risk associated with pastures with sycamores that have always been used without horses being poisoned
- the length of the risk periods.
Answers were found in a literature review and data gathered by AM surveillance networks. A guide is offered to differentiate common maple trees (FAQ1).
In order to reduce the risk of AM at pasture level: Avoid humid pastures; avoid permanent pasturing; avoid spreading of manure for pasture with sycamores in the vicinity and avoid sycamore maple trees around pasture (FAQ2).
To reduce the risk of AM at horse level: Reduce pasturing time according to weather conditions and to less than six hours a day during risk periods for horses on risk pasture; provide supplementary feeds including toxin-free forage; provide water from the distribution network; provide vitamins and a salt block (FAQ3). All pastures with a sycamore tree in the vicinity are at risk (FAQ4). Ninety-four percent of cases occur over two 3-month periods, starting in October and in March, for cases resulting from seeds and seedlings ingestion respectively (FAQ5).
IF YOU HAVE SYCAMORE TREES IN OR AROUND YOUR FIELDS….
- Do not graze horses in these fields!
If you cannot avoid using these fields….
- Fence off large areas as the seeds travel long distances when blown
- Feed horses before putting them out
- Limit time in these paddocks
- Remove as many seeds as possible with paddock vacuums
- Do not put food on the ground (hay, other)
- If you have to put out food, place it as far away from the trees as possible
IF YOU HAVE SYCAMORES
IF YOUR HORSE MAY HAVE EATEN SEEDS AND IF YOUR HORSE IS SHOWING SYMPTOMS OF AM
*** CONTACT YOUR VET IMMEDIATELY ***
Votion, D.-M.; François, A.-C.; Kruse, C.; Renaud, B.; Farinelle, A.; Bouquieaux, M.-C.; Marcillaud-Pitel, C.; Gustin, P. Answers to the Frequently Asked Questions Regarding Horse Feeding and Management Practices to Reduce the Risk of Atypical Myopathy. Animals 2020, 10, 365.
TO READ THE FULL PAPER:
The full paper can be downloaded here> https://www.mdpi.com/2076-2615/10/2/365