Equis ISSN 2398-2977

Eye: ocular discharge

Synonym(s): Ocular discharge

Contributor(s): Dennis E Brooks, Robert Lowe


  • Cause: ocular discharges can be caused by hypersecreation of tears or improper drainage of tears (epiphora).
  • Signs: many ocular diseases can present with an ocular discharge.
  • Diagnosis: increased lacrimation may be found with painful eye conditions and a full ophthalmic examination is necessary to rule out other diseases before concluding that the discharge is not a true epiphora.
  • Treatment: systemic therapy for drainage problems.
  • Prognosis: good to guarded depending on cause of discharge.





Excess lacrimation

Serous resembling water producing a fluid resembling serum

  • Infectious causes of conjunctivitis may result in a proteinaceous serous discharge. However, corneal rupture with aqueous leakage can also present as a serous discharge without much evidence of pain. 
  • Exercise caution when opening the eyelids of a horse with a serous discharge. Use an auriculopalpebral nerve block prior to examination of the globe. 
  • Aqueous leakage can be detected using a Seidels test. Seidels test looks for the dilution of 2% fluorescein with aqueous humor. A drop of fluorescein is placed on the eye and the corneal surface examined - at the site of leakage there will be a clearing of the typical fluorescein green as the aqueous runs down the cornea.


  • Dry eye in horses does not necessarily provoke the same degree of mucus production that gives rise to the classic appearance of keratoconjunctivitis sicca (KCS) in the dog.
  • Schirmer Tear Test 1 measurements should form part of all standard ophthalmic examinations, so this condition is unlikely to be missed.


  • Purulent discharges   Eye: purulent ocular discharge   contain inflammatory cells and are seen in ocular infections such as an infectious keratitis or conjunctivitis.


  • The main cause of hemorrhagic discharge is trauma; clinical examination should identify any damaged tissue. 
  • Hemorrhagic discharge can also be seen with squamous cell carcinoma (SCC) or other tumors.


  • Epiphora is an overflow of tears caused by abnormal drainage from the eye.
  • Epiphora may be congenital, traumatic, an extension from sinus or oral disease, or from a foreign body.


  • Congenital agenesis/atresia of the nasolacrimal system takes time to develop an infection which is why it is most common in yearlings.


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Further Reading


Refereed papers

Other sources of information

  • Brooks D (2002) Equine Ophthalmology. Teton New Media.