Diagnosing EPM

If your horse starts stumbling or exhibits any of the signs of EPM, you need to get your veterinarian involved immediately.

The earlier your veterinarian can diagnose EPM and begin treatment, the better chance your horse has for recovery. Unfortunately, EPM can be difficult to diagnose accurately.

If EPM is suspected, your veterinarian will perform a complete physical and neurological examination. Other tests may be indicated to rule out lamenesses and other neurologic diseases that can mimic EPM. A sample of blood and spinal fluid are often tested for antibodies against S. neurona using one of several laboratory tests, including the Western blot, IFAT and SAG-ELISA.

When performing a physical neurological exam, a veterinarian will test the horse in a variety of ways. An example of a neurologic exam performed on a healthy horse can be viewed in the video below.

  • Walk horse in straight line
  • Walk horse in crooked line
  • Circle horse tightly each direction to determine if the horse is aware of where he is putting his feet when they are challenged
  • Pull tail to one side while horse is walking to determine if horse is weak from side to side and to see if he can catch himself when pulled off balance
  • Cranial nerve exam to evaluate the nerves that control a variety of functions including control of the muscles of facial expression, movement of ears and eyes, balance and vision
  • Check tongue tone and test the horse's ability to retract their tongue and to swallow
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