• Cause: this condition occurs when horses ingest feed that is contaminated with the fungusFusarium moniliforme. This fungus produces many mycotoxins, including fumonisins, trichothecenes and zearalenone. Fumonisin B1 is the causative agent of leukoencephalomalacia.
• Signs: depression, aimless circling, head pressing, paresis, ataxia, blindness, and death.
• Diagnosis: history, clinical signs, neurological examination, cerebrospinal fluid analysis, necropsy.
• Treatment: supportive care.
• Prognosis: length of exposure, level of contaminant, individual animal differences, and previous exposure all impact the appearance and severity of clinical disease.

Presenting signs

• Early clinical signs:
  • Anorexia.
  • Lethargy.
  • Depression.
• Neurotoxicity:
  • Somnolence.
  • Weakness of face and pharyngeal muscles.
  • Ataxia.
  • Conscious proprioception deficits.
  • Facial desensitization.
  • Leaning.
• Hepatotoxicity:
  • Swelling of lips and nose.
  • Mucus membrane petechiae.
  • Icterus.
  • Abdominal breathing.
  • Cyanosis.
• Neurotoxicity and hepatotoxicity can occur independently or simultaneously. Higher doses of toxin favor hepatotoxicity and chronic ingestion of lower concentrations is associated with neurotoxicity.

Acute presentation

• Dementia.
• Blindness.
• Convulsions.
• Sudden death.

Geographic incidence

• Worldwide.

Cost considerations

• Euthanasia and necropsy of severely affected animals in order to confirm the diagnosis may be the most economical strategy.

Special risks

• Caution should be taken when examining and treating a severely neurologic animal.