Conjunctivitis

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• Inflammation of the mucous membrane lining the eyelids, nictitans, scleral part of the globe and lacrimal canaliculi.
• Common - acute, chronic, allergic and 'special' types.
• Cause: varied - traumatic, infectious (particularly feline herpesvirus), immune-mediated; maybe secondary to other concurrent ocular or systemic disease.
• Signs: hyperemia, edema, ocular discharge (serous mucopurulent), blepharospasm, photophobia; severe cases adhesions ; chronicity thickening.
• Diagnosis: physical examination; swabs, scrapings microbiology FHV-1 viral isolation or PCR (when available); Schirmer tear test; serum antibody titer (chlamydial infection).
• Treatment: depends on cause, eg topical antibiotics, removal of any physical cause, corticosteroids, analgesia.
• Prognosis: generally good; dependant on management of underlying causes.

• Feline herpesvirus infection in kittens may severe keratoconjunctivitis symblepharon.

• Breeds predisposed to entropion.
• Breeds with long facial hair.

• Entropion .
• Foreign body .

Acute - infection

• May be primary or secondary, ie extension from systemic infection.
• Important primary pathogens:
  • Herpesvirus .
  • Chlamydia spp .
• Tends to cause minor ocular signs:
  • Calicivirus .
• Opportunistic infection:
  • Staphylococcus spp .
  • Beta-hemolytic streptococci .
  • Proteus spp .
  • Escherichia coli .
  • Pseudomonas spp .
  • Neisseria spp .
• Other:
  • Mycoplasma spp - experimentally shown to cause conjunctivitis in cats.

Chronic

• Misdiagnosis/ineffective therapy.
• Underlying systemic disease, eg FeLV or FIV .
• Neoplasia, eg lymphoma.

Allergic

• Inhaled, contact allergens.
• Bacterial, eg staphylococcal allergens.

Special

• Follicular - unknown but may be linked to chronic irritation; chlamydial infection may lymphoid follicles.
• Keratoconjunctivitis sicca - deficient tear production.

• Breed.
• Long facial hair.
• Very active outdoors.
• Breeding establishments and colonies may have problems with Chlamydia and respiratory viruses.

• 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

• Follicular - lymphoid hyperplasia on nictitans and palpebral conjunctiva trauma inflammatory response.
• Keratoconjunctivitis sicca .

• Ocular discharge.
• Blepharospasm .
• Swollen, red conjunctiva.
   Pinker appearance of fornix conjunctiva can lead to a misdiagnosis of conjunctivitis.

• History.
• Clinical signs.
• Microbiology - virus isolation or PCR (polymerase chain reaction) when available.
• Fluorescein test - for evidence of concurrent corneal trauma or virally-mediated corneal ulceration.
• Schirmer tear test .
• Serum antibody titer (Chlamydia).

• Keratitis .
• Corneal ulceration .

• Epiphora .
• Prolapsed nictitating membrane .
• Anterior uveitis .

• Remove physical cause.
• Remove all accumulated discharge with moistened cotton swab several times daily.
• First use topical antibiotic (tetracycline). If no response test for viral etiology with trifluorothyridine or 2-cyclovir as possible therapeutic choices.
• Topical antimicrobials +/- corticosteroids .
   CARE! Ensure no associated corneal ulceration. Also, in cats, topical steroids may reactivate latent herpesvirus infection.
• Analgesia may be necessary.

Acute - secondary

• Treat primary condition.
• As above.

Chronic

• Reinvestigate to confirm or correct diagnosis.
• As above.

Allergic

• Corticosteroids .
• Antihistamines .

Special

• Follicular - topical or general anesthesia scrape conjunctiva with a dry cotton swab held with forceps to remove follicles, irrigate with saline + topical corticosteroids +/- antibiotic for 7-10 days.
• Keratoconjunctivitis sicca .

• Response to topical therapy.

• Treat underlying condition.
• Grooming of facial hair.

• Vaccination against Chlamydia.
• Avoid recognized allergens.

• Do not breed from animals with entropion.

• Good.
• Depends on management of underlying causes.
• Follicular conjuctivitis - can be recurrent.

• Resolution of signs within 24-48 hours.
• No recurrence following treatment.

• Standard reasons .

• TerWee J et al (1998) Characterization of the systemic disease and ocular signs induced by experimental infection with Chlamydia psittaci in cats. Vet Microbiol 59 (4), 259-281.

• Petersen-Jones S & Crispin S (2002) BSAVA Manual of Small Animal Ophthalmology. 2nd edn. British Small Animal Veterinary Association. ISBN 0 905214 54 4

• Dr Dennis E Brooks DVM PhD DipACVO
• Mr Peter Renwick MA VetMB DVOphthal MRCVS
• Dr David Williams MA VetMB PhD CertVOphthal FRCVS

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