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Archive Case #227: Ovine Sheep Scab

Sheep veterinary case - Easy - October 16, 2026

Clinical Clues

  1. Several sheep in a recently mixed flock begin rubbing against fences and losing patches of fleece.
  2. The pruritus is intense, with affected animals repeatedly biting at their flanks.
  3. Parting the fleece reveals moist crusted lesions that extend beyond the first affected animal.
  4. Lice are considered, so samples are collected from the active edge of several lesions.
  5. Superficial skin scrapings contain live mites with psoroptic morphology rather than lice.
  6. Identification of Psoroptes ovis from the lesions confirms sheep scab, or psoroptic mange, in the flock.

Diagnosis

Ovine Sheep Scab

Contagious severe itch, fleece loss and identification of P. ovis support sheep scab. Lice and other mites can produce overlapping signs, so the observed parasite matters more than the appearance of the crusts alone. Remember: Severe flock pruritus raises suspicion of sheep scab, but identification of Psoroptes ovis distinguishes it from lice and other mite infestations.

Learning review

Review the case evidence

Use the paired clues to explain how the evidence in this sheep case supports the provided diagnosis, Ovine Sheep Scab, then compare your reasoning with the case explanation.

Evidence checkpoints

Clues 1-2

  1. Clue 1: Several sheep in a recently mixed flock begin rubbing against fences and losing patches of fleece.
  2. Clue 2: The pruritus is intense, with affected animals repeatedly biting at their flanks.

Clues 3-4

  1. Clue 3: Parting the fleece reveals moist crusted lesions that extend beyond the first affected animal.
  2. Clue 4: Lice are considered, so samples are collected from the active edge of several lesions.

Clues 5-6

  1. Clue 5: Superficial skin scrapings contain live mites with psoroptic morphology rather than lice.
  2. Clue 6: Identification of Psoroptes ovis from the lesions confirms sheep scab, or psoroptic mange, in the flock.

Self-review prompts

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

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.