Eyeworm disease

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Eyeworm Disease

Thelaziasis

Eyeworm disease in horses is caused by the eyeworm (Thelazia spp.) parasite, which is transmitted by face flies. Thelazia lacrymalis is usually the parasite associated with most occurrences. The symptoms associated with eyeworm disease are sometimes absent or can vary from mild to severe conjunctivitis (pink eye) or inflammation of other areas of the eye including the cornea, tear ducts, tear sacs and eyelid.

Symptoms

Eye redness
Eye discharge
Eye itchiness
Swelling
No clinical signs

Diagnosis

  • History
  • Clinical Signs
  • Physical exam

Treatment


TreatmentDetails
Removal of eyeworms by forceps
Flushing eyes with an iodine solution or iodine ointment
Antibiotic-steroid ointment

Prevention

  • Use protective fly masks on horses when flies are abundant
  • Proper control of insects on property

Scientific Research References

Good Overviews

Risk Factors

  • High populations of face flies on premises
  • Horses living on the same property as bordering property containing cattle

Seasonality

WinterSpringSummerAutumn