canis - Articles
Conjunctivitis
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.
Presenting signs
- Red eye.
- Mucopurulent - purlent ocular discharge.
- Excessive blinking.
Geographic incidence
- Tropical environments may predispose to increased incidence of conjunctivitis.
Breed/Species predisposition
Acute +/- chronic- Breeds predisposed to allergic or immune-mediated skin diseases.
- Breeds predisposed to entropion.
- Breeds with long facial hair.
- Breeds associated with outdoor activity, eg hunting.
- German Shepherd Dog German Shepherd Dog.
Cost considerations
- Simple medical treatment usually adequate.
- Problem may be recurrent.
Pathogenesis
Etiology
Acute - traumatic- Entropion Entropion.
- Foreign body.
- Staphylococcus Staphylococcus spp.
- Beta hemolytic streptococci Streptococcus spp.
- Proteus.
- E. coli Escherichia coli.
- Pseudomonas Pseudomonas aeruginosa.
- Neisseria.
- Mycoplasma Mycoplasmas and ureaplasmas - often isolated, probably not primary pathogen.
- Distemper virus Canine distemper disease.
- May be primary or secondary, ie extension from systemic infection (rare).
- Atopy Skin: atopy.
- Contact allergens Skin: allergic contact dermatitis.
- Bacterial, eg Staphylococcal allergens.
- 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.
- Systemic infection → localization of micro-organism in mucous membranes including conjunctiva → inflammatory response.
- Misdiagnosis/ineffective therapy.
- Allergen → anaphylactic/immune-complex/cell-mediated response → chemosis, profuse lacrimation.
- Follicular - lymphoid hyperplasia on membrane and palpebral conjunctivae → trauma → inflammatory response.
- Plasma cell/lymphocytic - with corneal pannus Chronic superficial keratitis.
- Keratoconjunctivitis sicca Keratoconjunctivitis sicca.
- 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
- Recent references from PubMed and VetMedResource.
Other sources of information
- Gelatt K N (1999)Veterinary Opthamology.: 3rd edn: Williams & Wilkins.