Summer sores • cutaneous habronemiasis • habronemiosis

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  • A seasonal condition characterized by mildly pruritic, reddish-brown granulomatous lesions.
  • Cause : aberrant intradermal migration of larvae of stomach worms: Habronema muscae , Habronema majus and Draschia megastoma .
  • Signs : granulomatous lesions occur in medial canthus of eye, around male genitalia and on uncovered wounds.
  • Diagnosis : history and clinical signs are suggestive. Confirmation is by skin biopsy.
  • Treatment : debulk lesion (may involve amputation of urethral process), anti-inflammatories, parasiticides to reduce size of lesion, reduce inflammation and to prevent re-infestation.
  • Prognosis : strict adherence to fly control measures and wound control for life in hypersensitive animals.
  • See also:


Differential diagnosis

All of the above may be secondarily infected with Habronema larvae.

  • Pythiosis.
  • All of the above can occur and be infested with larvae.


Clinical signs

  • Tongue: habronemiasis ulcerFig.1 Tongue: habronemiasis ulcer
    Mildly pruritic, reddish-brown granulomatous lesions - wounds tend to become saucer shaped with raised edges   (Fig. 1)  .
  • Variable serosanguinous exudate, often exhibiting gritty, yellow nodules on cut section.
  • Skin: habronemiasis 02 - pasternFig.2 Skin: habronemiasis 02 - pastern
    Lesions commonly in medial canthus of eye, around penis, prepuce and urethral process of male horses, and in uncovered wounds   (Fig. 2)  .
  • Skin:
    • Variably pruritic, variably infected, non-healing granulomatous skin lesions.
    • Often on distal extremities.
  • Male genitalia:
    • Penis: habronemiasisFig.3 Penis: habronemiasis
      Granulomatous and often ulcerative lesions on prepuce and urethral process of male horses   (Fig. 3)  .
    • Localized swelling and edema of prepuce.
    • Preputial discharge; often serosanguinous.
    • Hemospermia  [Semen: evaluation]  .
  • Ocular lesions:
    • Granulomatous lesions at medial canthus of eyes on conjunctivae and eyelids         . (Figs. 4-5)
    • Ocular discharge    .
  • Occasionally lesions become massive, particularly around the male genitalia.
  • Gastrointestinal   (Fig. 1, above)  :



  • Strict adherence to fly control measures and wound care is essential for life in hypersensitive animals.
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