Equine Atypical Myopathy
Recently there have been reports of horses suddenly dying on pastures in West Cornwall from a new/emerging condition in the UK called Equine Atypical Myopathy (EAM).EAM causes sudden disintegration of muscles (rhabdomyolysis) in horses of any age on pastures in the autumn. Clinically the horses appear quiet, stiff, reluctance to walk, depressed and can become recumbent if not seen early; unfortunately EAM has a high mortality rate.
When and where
- Sporadic condition mainly in autumn, after spells of warmth, heavy rain, humidity and winds.
- Occurs in cluster areas with several horses affected on same pasture.
- Wet, boggy, leafy fields.
- Any age of horse, no sex/breed predisposition but young females overrepresented.
- Animals not in training, good/bad condition.
Causes
- No known cause but factors including weather conditions, poor health status and certain leafy pastures may predispose.
- Dead leaves, humidity may favour growth of moulds/mycotoxins that may increase risk of EAM.
- Speculation that a toxin producing bacterium called Clostridium sordellii and bifermantans may have a role in the disease.
- Poor antioxidant status of horse may predispose horses to EAM.
Clinical signs
(clinical signs described below are from two horses seen by Animal Veterinary Services)
- Acute onset of dullness, head down, reluctant to walk, stiff legs with hindlimbs>forelimbs.
- Mild sweating especially in the pectoral region, flanks.
- Reduced appetite, water intake, urination/defecation but no overt signs of “colic”.
- Increased respiratory rate, heart rate, gum colour from pale pink to darker pink.
- As the disease progresses the above become exaggerated with eventually recumbancy, dark brown urine (muscle breakdown products) and eventually death.
Veterinary treatment/prevention
- EAM does have a very high mortality rate but early intervention can lead to recovery.
- Clinical signs described along with a blood sample can greatly increase the probable diagnosis of EAM.
- If your horse appears as above do not walk your horse and call your veterinary surgeon.
- The main aims of treatment include pain relief, intravenous fluids, antibiotics and husbandry for the recumbent horses. Treatment does not guarantee a positive result.
- Antioxidants including vitamin E/Selenium, salt blocks may help.
- Regular pasture management, poo-picking, vaccination, worming regimes, feeding, exercise.
If you have any concerns or questions please call and speak to Jonathan McCotter MRCVS