Conjunctivitis in Cats: Welfare and Treatment
Types of Feline Conjunctivitis
Conjunctivitis (inflammation of the conjunctiva) is among the most common feline conditions. Key causes: feline herpesvirus type 1 (FHV-1) — most common infectious cause, typically affecting young cats and causing recurrent flares; Chlamydophila felis — causes persistent, often bilateral conjunctivitis; Mycoplasma spp.; and non-infectious causes (trauma, foreign body, anatomical abnormalities, environmental irritants). Distinguishing between causes guides appropriate treatment.
Welfare Impact
Conjunctivitis causes significant discomfort: ocular discharge (serous, mucoid, or mucopurulent), conjunctival hyperaemia (redness), chemosis (swelling), blepharospasm (squinting), and photophobia. Affected cats paw at their eyes and may show reduced activity and social engagement. Chronic or untreated conjunctivitis can progress to corneal involvement (symblepharon from FHV-1, corneal ulceration) causing more severe welfare compromise. Pain management through treatment is the immediate welfare priority.
Diagnosis
Thorough ophthalmic examination identifies the type and severity of conjunctivitis. Fluorescein staining detects corneal ulceration. Conjunctival swabs for PCR (FHV-1, Chlamydophila, Mycoplasma) guide specific treatment. Examination of both eyes (often both affected in infectious causes), assessment of nasal discharge, and systemic examination complete the picture. Rule out ectopic cilia, entropion, and other anatomical abnormalities in predisposed breeds.
Treatment by Cause
FHV-1: topical antiviral (cidofovir 0.5% twice daily), systemic famciclovir in severe cases; avoid topical corticosteroids (worsen viral disease). Chlamydophila felis: topical (chloramphenicol) or systemic doxycycline for 4-6 weeks (must treat all cats in household). Mycoplasma: responds to topical or systemic tetracyclines. Non-specific bacterial: topical chloramphenicol or fusidic acid. Non-infectious: treat underlying cause, lubricant eye drops, surgical correction of anatomical abnormalities.
Prevention and Long-term Management
FHV-1 vaccination (as part of core feline vaccination) reduces severity but does not prevent infection. Multi-cat households with recurrent FHV-1 outbreaks benefit from stress reduction measures (Feliway, adequate space and resources), antiviral prophylaxis during high-stress periods, and minimising population density. Chlamydophila felis vaccination is available in the UK as a non-core vaccine for at-risk cats. Regular veterinary eye examinations in cats with recurrent disease monitor for complications.