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Archive Case #58: Ovine Contagious Ecthyma

Sheep veterinary case - Medium - April 30, 2026

Clinical Clues

  1. A young lamb is examined for crusting lesions around the lips and nostrils.
  2. The farmer reports several lambs in the group have developed similar sores after marking.
  3. The lesions are proliferative and painful rather than purely erosive.
  4. Despite the mouth lesions, the lamb remains reasonably bright.
  5. The pattern is consistent with a contagious parapoxvirus infection of sheep.
  6. Contagious ecthyma (orf) commonly produces scabby proliferative lesions around the mouth of lambs and can spread rapidly through a flock.

Diagnosis

Ovine Contagious Ecthyma

This case is most consistent with Ovine Contagious Ecthyma because the lamb has classic proliferative crusting lesions around the mouth with flock spread. The most important clues are the age group, lesion distribution, and contagious pattern, which strongly support orf.

Learning review

Review the case evidence

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

Evidence checkpoints

Clues 1-2

  1. Clue 1: A young lamb is examined for crusting lesions around the lips and nostrils.
  2. Clue 2: The farmer reports several lambs in the group have developed similar sores after marking.

Clues 3-4

  1. Clue 3: The lesions are proliferative and painful rather than purely erosive.
  2. Clue 4: Despite the mouth lesions, the lamb remains reasonably bright.

Clues 5-6

  1. Clue 5: The pattern is consistent with a contagious parapoxvirus infection of sheep.
  2. Clue 6: Contagious ecthyma (orf) commonly produces scabby proliferative lesions around the mouth of lambs and can spread rapidly through a 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 Contagious Ecthyma?
  3. How do clues 5-6 align with the case explanation for Ovine Contagious Ecthyma?

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.