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Vetdle Archive

Archive Case #157: Bovine Polioencephalomalacia

Cattle veterinary case - Hard - August 7, 2026

Clinical Clues

  1. A young steer on a high-concentrate ration becomes dull and separates from the group.
  2. The owner reports sudden blindness and aimless wandering.
  3. On examination the animal is depressed with dorsomedial strabismus and intermittent star-gazing.
  4. Menace response is absent but pupillary light reflexes are preserved.
  5. The neurologic pattern localises to the cerebral cortex rather than the spinal cord.
  6. Cerebrocortical necrosis associated with thiamine imbalance or sulphur excess causes this syndrome in cattle.

Diagnosis

Bovine Polioencephalomalacia

This case is most consistent with Bovine Polioencephalomalacia because the steer has cortical blindness, forebrain signs, and a ration history that predisposes to cerebrocortical necrosis. The most important clues are the absent menace with intact pupillary reflexes and the cerebral localisation, which make ocular disease less likely.

Learning review

Review the case evidence

Use the paired clues to explain how the evidence in this cattle case supports the provided diagnosis, Bovine Polioencephalomalacia, then compare your reasoning with the case explanation.

Evidence checkpoints

Clues 1-2

  1. Clue 1: A young steer on a high-concentrate ration becomes dull and separates from the group.
  2. Clue 2: The owner reports sudden blindness and aimless wandering.

Clues 3-4

  1. Clue 3: On examination the animal is depressed with dorsomedial strabismus and intermittent star-gazing.
  2. Clue 4: Menace response is absent but pupillary light reflexes are preserved.

Clues 5-6

  1. Clue 5: The neurologic pattern localises to the cerebral cortex rather than the spinal cord.
  2. Clue 6: Cerebrocortical necrosis associated with thiamine imbalance or sulphur excess causes this syndrome in cattle.

Self-review prompts

  1. After clues 1-2, what evidence from this cattle case shaped your initial interpretation?
  2. When you compare clues 3-4 with clues 1-2, what changed in your reasoning about Bovine Polioencephalomalacia?
  3. How do clues 5-6 align with the case explanation for Bovine Polioencephalomalacia?

Educational Use

Vetdle archive cases are educational veterinary games for diagnostic reasoning practice. They do not provide veterinary advice, diagnosis, treatment, or professional medical guidance.