Canis ISSN: 2398-2942

Conjunctivitis

Contributor(s): Dennis E Brooks, David L Williams

Introduction

  • Inflammation of the mucous membrane lining the eyelids, membrana nictitans, scleral part of the globe and lacrimal canaliculi.
  • Common - acute, chronic, allergic and 'special' types.
  • Cause: varied - traumatic, infectious, immune-mediated; may be secondary to other concurrent ocular or systemic disease.
  • Signs: congestion of conjunctival blood vessels, swelling, ocular discharge (lacrimous/serous → mucopurulent), blepharospasm, photophobia; less commonly follicle formation, edema.
  • Diagnosis: physical examination; swabs, scrapings → microbiology; Schirmer tear test.
  • Treatment: depends on cause, eg topical antibiotics, removal of any physical cause, corticosteroids, analgesia.
  • Prognosis: good.
    Print off the owner factsheet on Conjunctivitis in dogs to give to your client.

Pathogenesis

Etiology



Acute - traumatic Acute - infection Allergic Special
  • Follicular - unknown.
  • Plasma cell/lymphocytic - associated with corneal pannus Chronic superficial keratitis.
  • Neoplasia - melanomas, hemangiomas, lymphoma.

Predisposing factors

General
  • Breed.
  • Long facial hair.
  • Very active outdoors.

Specific

  • Deficient tear production.

Pathophysiology



Acute - primary
  • Trauma → tissue injury +/- introduction of bacteria → inflammatory response.
Acute - secondary
  • Systemic infection → localization of micro-organism in mucous membranes including conjunctiva → inflammatory response.
Chronic
  • Misdiagnosis/ineffective therapy.
Allergic
  • Allergen → anaphylactic/immune-complex/cell-mediated response → chemosis, profuse lacrimation.
Special
  • Trauma to conjunctiva → inflammation and possible epthelial ulceration.
  • Chronic disease → squamous metaplasia of epithelium.
  • Primary inflammation of conjunctiva may → predisposition to secondary bacterial infection.
  • Can be primary, eg allergic, infectious, environmental and KCS or secondary to an underlying ocular or systemic disease, eg glaucoma, uveitis, neoplasia, keratitis.
  • The loose arrangement of the conjunctival stroma permits rapid edema.
  • Stroma vasculature and lymphoid tissue permit acute development of hyperemia.
  • Multinucleated giant cells are seen in chronic conjunctivitis.
  • Keratinized epithelial conjunctival cells and goblet cell proliferation occur in chronic conjunctivitis.

Timecourse

  • Acute conjunctivitis may be the first manifestation of anteroir uveitis, corneal ulceration and glaucoma.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

Other sources of information

  • Gelatt K N (1999)Veterinary Opthamology.: 3rd edn: Williams & Wilkins.


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