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Vetdle Archive

Archive Case #225: Equine Habronemiasis

Horse veterinary case - Easy - October 14, 2026

Clinical Clues

  1. A horse develops a moist, nonhealing sore beside the medial corner of one eye during the fly season.
  2. The lesion persists despite ordinary wound care and becomes raised and irritated.
  3. Close examination finds yellow, gritty material embedded in the ulcerated granulation tissue.
  4. Flies repeatedly visit the moist periocular lesion, and the owner recalls a similar seasonal episode.
  5. A lesion scraping reveals spirurid larvae with features consistent with the stomach-worm group carried by flies.
  6. The seasonal periocular granuloma and identified larvae support cutaneous habronemiasis, often called a summer sore.

Diagnosis

Equine Habronemiasis

The nonhealing periocular ulcer, yellow calcified material, fly association and larvae support cutaneous habronemiasis. A traumatic wound or exuberant granulation tissue can look similar early, but neither explains the characteristic seasonal parasite finding. Remember: A nonhealing summer lesion near a horse’s eye with yellow gritty material should prompt investigation for cutaneous habronemiasis, not just repeat wound care.

Learning review

Review the case evidence

Use the paired clues to explain how the evidence in this horse case supports the provided diagnosis, Equine Habronemiasis, then compare your reasoning with the case explanation.

Evidence checkpoints

Clues 1-2

  1. Clue 1: A horse develops a moist, nonhealing sore beside the medial corner of one eye during the fly season.
  2. Clue 2: The lesion persists despite ordinary wound care and becomes raised and irritated.

Clues 3-4

  1. Clue 3: Close examination finds yellow, gritty material embedded in the ulcerated granulation tissue.
  2. Clue 4: Flies repeatedly visit the moist periocular lesion, and the owner recalls a similar seasonal episode.

Clues 5-6

  1. Clue 5: A lesion scraping reveals spirurid larvae with features consistent with the stomach-worm group carried by flies.
  2. Clue 6: The seasonal periocular granuloma and identified larvae support cutaneous habronemiasis, often called a summer sore.

Self-review prompts

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

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.