Atypical Myopathy

by Eryl V. Davies BVSc MRCVS

by Eryl V. Davies BVSc MRCVS

This autumn has seen a large increase in the number of cases of atypical myopathy in our area. The disease has been linked to the ingestion of sycamore seeds, but many other trees of the Acer family have been implicated (e.g. Acer pseudoplatamus – the maple tree). The disease was first documented some 6-8 years ago as a sporadic “outbreak” on certain equestrian properties. “Myopathy” is Greek in origin and means “muscle suffering,” and is a neuromuscular disease in which the muscle fibres do not function for whatever reason.

Acer pseudoplatamus

Acer pseudoplatamus

Myopathies in horses are usually due to specific causes, for example:-

1.) “Tying up syndrome”: the horse’s muscles stiffen up due to the build up of lactic acid. This occurs after excessive feeding followed by rest and sudden, strenuous exercise.

2.) Post operative myopathy: the circulation of the muscles has been compromised following a long general anaesthetic with the horse lying on a relatively hard operating table.

ATYPICAL MYOPATHY is so-named because horses don’t show the typical signs seen in the above examples. Instead the clinical signs can vary from mild muscle weaknesses, colic-like behaviour, laboured breathing or passing red-brown urine and profuse sweating. Even when the disease is spotted at a relatively early stage treatment does not necessarily have a good outcome.

TREATMENT is best carried out at the veterinary surgery, so that intravenous fluid therapy can be administered and monitored. However some horses may already be unable to get up when the vet arrives at the premises, so transport to the surgery is not possible or desirable (increased stress and chance of injury.)



PREVENTION of this very distressing and debilitating disease is based on lowering the exposure to mature Acer seeds when they drop in the autumn. This can be done by:-

1.) Feeding supplementary forage (e.g. hay) in the field, reducing the temptation for horses to ingest seeds.

2.) Fencing off affected areas (although high winds will carry the seeds from your neighbours’ fields).

3.) Limit the horses’ time on pasture (maybe use the outdoor school for loafing, if you have one).

Sycamores and other Acer trees do provide very good shade in the summertime so bear this in mind when considering removing the trees from your property.

Why is there a disproportionate number of cases in the South-East? I believe there are two reasons:-

1.) We have a very high density equine population here.

2.) We live in a very wooded part of the country.

Sycamores pods

Sycamore pods

I sympathise with anyone who has seen their horse or pony suffering from this condition. i have personally attended three cases this autumn, all of which unfortunately had to be put to sleep. Please be vigilant in checking your horses and ponies as early diagnosis can sometimes help survival rate.

All of us at Putlands Veterinary Surgery wish our clients and readers a peaceful and joyous Christmas and a happy New Year.

STOP PRESS: Promotion of the Month. Due to the increased prevalence of Equine Influenza this year we are offering a free 2nd injection of a course (if your horse’s vaccinations have run out).

If you have any questions about any aspects of your horse’s health, or indeed your pet, farm or smallholding animals, please do not hesitate to contact us on 01892 835456. Putlands Veterinary Surgery is based in Paddock Wood in Kent, and offers a friendly, professional and personal service for all species of animal. We have four dedicated large animal vets with a wealth of equine experience between us, and are always happy to helpsycamore-seed

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