NFED Equine Health & Welfare

Equine Atypical Myopathy (EAM)
Information kindly provided by Celtic Equine
02380 814155

Clinical signs (in order of frequency)

• Acute onset weakness and dullness
• Reluctant to rise/walk
• Stiff legs with hindlimbs > forelimbs
• Dark coloured urine
• Red or purple mucus membranes/gums
• Depressed
• Muscle Tremors
• Difficulty in staying standing
• Increased heart rate
• Sweating espically in the neck/shoulder area and flanks
• Hypothermia
• Colic

Recent cases seen by Liphook Equine Hospital also displayed the following signs in the day before the normal clinical signs of EAM were observed
• Vigorous head-shaking and nodding
• Frenzied vocalisation
• Choke-like retching neck spasms when feeding
• Lethargic when ridden

Veterinary treatment/prevention

• EAM does have a very high mortality rate but early intervention can lead to recovery.
• Survival rate even with early diagnosis and intensive hospital treatment of approximately 25%
• 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.
• Removal of all other horses from affected pasture as soon as case of EAM has been confirmed.

When and where does EAM occur

• Sporadic condition occuring 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, poor bad condition, unvaccinated and unwormed are also more at risk.

Causes of EAM

• 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.

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