Signs of EPM

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The clinical signs of EPM can be quite varied. Clinical signs are almost always asymmetrical (not the same on both sides of the horse). Actual signs may depend on the severity and location of the lesions that develop in the brain, brain stem or spinal cord. Signs may include:

• Ataxia (incoordination), Spasticity (stiff, stilted movements), abnormal gait or lameness
• Incoordination and weakness which worsens when going up or down slopes or when head is elevated
• Muscle atrophy, most noticeable along the topline or in the large muscles of the hindquarters, but can sometimes involve the muscles of the face or front limbs
• Paralysis of muscles of the eyes, face or mouth, evident by drooping eyes, ears or lips
• Difficulty swallowing
• Seizures or collapse
• Abnormal sweating
• Loss of sensation along the face, neck or body
• Head tilt with poor balance; horse may assume a splay-footed stance or lean against stall walls for support
• Three things seem to influence progression of the disease:
  1. The extent of the infection (i.e. the number of organisms ingested)
  2. How long the horse harbors the parasite prior to treatment
  3. The point(s) in the brain or spinal cord where the organism localizes and damage occurs

Learn More: Horses at Risk