Conjunctivitis
Learn what the condition is, how it may be detected early, how it is treated or managed, and which breeds or species are linked to it.
Condition snapshot
A concise guide to the condition’s pattern, detection, management and urgency.
This snapshot is a general guide, not a diagnosis or treatment plan. New, severe or worsening signs require veterinary assessment.
About the condition
Conjunctivitis is inflammation of the conjunctiva, the thin tissue lining the eyelids and covering part of the eye. It causes redness, swelling and discharge but does not describe one single cause. In cats, common triggers include feline herpesvirus, Chlamydia felis, other respiratory infections, irritation and, less commonly, allergy or structural eyelid problems.
One or both eyes may be affected. Discharge can be clear and watery or become thicker and mucopurulent. The third eyelid may become more visible, and the cat may squint or rub the face. Kittens with upper respiratory disease often have conjunctivitis alongside sneezing and nasal discharge.
The cornea must be assessed separately because a painful corneal ulcer can initially look like simple conjunctivitis. Herpesvirus is a particular concern because it can cause both conjunctival inflammation and ulceration. Severe swelling can also hide a foreign body or other ocular problem.
Fluorescein stain is commonly used to detect corneal ulcers before topical medication is selected. The veterinarian may examine tear production, eyelid position and the inside of the third eyelid.
Conjunctivitis is usually treatable, but treatment must match the cause. Antibiotic drops do not treat herpesvirus, and steroid-containing eye medication can worsen certain corneal infections. This is why a red eye should be examined before leftover medication from a previous episode is used.
The colour and thickness of discharge can suggest whether secondary bacteria are involved, but it does not identify the original cause reliably. A viral eye can develop thick discharge, and a bacterial-looking eye can still have a corneal ulcer.
This determines whether certain medications are safe. In kittens or multi-cat outbreaks, the pattern of respiratory and eye signs can suggest herpesvirus, Chlamydia or another pathogen. Early detection depends on recognising that persistent ocular discharge is not merely cosmetic.
Screening & Early Detection
Any eye that is red, swollen, producing discharge or causing the cat to squint should be examined if signs persist, recur or appear painful. Holding the eye closed, cloudiness of the cornea or sudden sensitivity to light warrants more urgent assessment.
Fluorescein staining is a key early test because it shows damage to the corneal surface. The veterinarian also checks eyelid conformation, the third eyelid and the presence of foreign material.
PCR testing may be useful when confirmation changes treatment, but positive results require clinical interpretation because some organisms can be carried without causing all current signs.
There is no routine screening test for healthy cats. A cat with recurrent conjunctivitis should be assessed for herpesvirus, structural problems or chronic corneal disease rather than receiving repeated empirical eye drops indefinitely.
Diagnosis begins with eye examination. PCR testing for infectious organisms is useful in selected persistent cases or outbreaks, but many uncomplicated cases are diagnosed clinically. Examination of the ocular surface therefore remains more important than choosing treatment from discharge colour alone.
Treatment & Management
Treatment is cause-specific. Bacterial conjunctivitis or Chlamydia felis may require antibiotic therapy, while herpesvirus-associated disease can need antiviral medication. Lubricating drops may improve comfort and protect the ocular surface in selected cases.
The eyes and surrounding fur can be cleaned gently with sterile saline or another veterinarian-recommended method. Human eye drops should not be used without advice. In particular, corticosteroid-containing eye medication can be dangerous when a corneal ulcer or active herpesvirus infection is present.
Painful cats may need systemic analgesia, and severe swelling or poor appetite from concurrent respiratory disease requires broader supportive care. In multi-cat households, hygiene and temporary separation of actively symptomatic cats can reduce spread when an infectious cause is likely.
Response should be visible within the expected treatment period. Persistent redness, worsening discharge or new corneal cloudiness requires re-examination rather than simply extending the same medication. Most uncomplicated conjunctivitis resolves well, but recurrent disease is common with latent herpesvirus and needs a plan that addresses the underlying cause.
Cats with recurring herpes-associated conjunctivitis may need an agreed plan for early antiviral treatment during future flares rather than restarting random leftover eye drops.
Breeds or species affected
Abyssinian
Open cat breed description, care requirements and conditions
American Bobtail
Open cat breed description, care requirements and conditions
American Curl
Open cat breed description, care requirements and conditions
American Shorthair
Open cat breed description, care requirements and conditions
American Wirehair
Open cat breed description, care requirements and conditions
Arabian Mau
Open cat breed description, care requirements and conditions
Aegean
Open cat breed description, care requirements and conditions
Australian Mist
Open cat breed description, care requirements and conditions
Balinese
Open cat breed description, care requirements and conditions
Bengal
Open cat breed description, care requirements and conditions
Birman
Open cat breed description, care requirements and conditions
Bombay
Open cat breed description, care requirements and conditions
British Longhair
Open cat breed description, care requirements and conditions
British Shorthair
Open cat breed description, care requirements and conditions
Burmese
Open cat breed description, care requirements and conditions
Burmilla
Open cat breed description, care requirements and conditions
Chartreux
Open cat breed description, care requirements and conditions
Chausie
Open cat breed description, care requirements and conditions
Colorpoint Shorthair
Open cat breed description, care requirements and conditions
Cornish Rex
Open cat breed description, care requirements and conditions
Cymric
Open cat breed description, care requirements and conditions
Devon Rex
Open cat breed description, care requirements and conditions
Domestic Longhair
Open cat breed description, care requirements and conditions
Domestic Medium Hair
Open cat breed description, care requirements and conditions
Domestic Shorthair
Open cat breed description, care requirements and conditions
Donskoy
Open cat breed description, care requirements and conditions
Egyptian Mau
Open cat breed description, care requirements and conditions
European Shorthair
Open cat breed description, care requirements and conditions
Exotic Shorthair
Open cat breed description, care requirements and conditions
Havana Brown
Open cat breed description, care requirements and conditions
Highlander
Open cat breed description, care requirements and conditions
Himalayan
Open cat breed description, care requirements and conditions
Japanese Bobtail
Open cat breed description, care requirements and conditions
Khao Manee
Open cat breed description, care requirements and conditions
Korat
Open cat breed description, care requirements and conditions
Kurilian Bobtail
Open cat breed description, care requirements and conditions
LaPerm
Open cat breed description, care requirements and conditions
Lykoi
Open cat breed description, care requirements and conditions
Maine Coon
Open cat breed description, care requirements and conditions
Manx
Open cat breed description, care requirements and conditions
Minuet
Open cat breed description, care requirements and conditions
Minskin
Open cat breed description, care requirements and conditions
Munchkin
Open cat breed description, care requirements and conditions
Nebelung
Open cat breed description, care requirements and conditions
Norwegian Forest Cat
Open cat breed description, care requirements and conditions
Ocicat
Open cat breed description, care requirements and conditions
Oriental Longhair
Open cat breed description, care requirements and conditions
Oriental Shorthair
Open cat breed description, care requirements and conditions
Persian
Open cat breed description, care requirements and conditions
Peterbald
Open cat breed description, care requirements and conditions
Pixiebob
Open cat breed description, care requirements and conditions
RagaMuffin
Open cat breed description, care requirements and conditions
Ragdoll
Open cat breed description, care requirements and conditions
Russian Blue
Open cat breed description, care requirements and conditions
Savannah
Open cat breed description, care requirements and conditions
Scottish Fold
Open cat breed description, care requirements and conditions
Scottish Straight
Open cat breed description, care requirements and conditions
Selkirk Rex
Open cat breed description, care requirements and conditions
Siamese
Open cat breed description, care requirements and conditions
Siberian
Open cat breed description, care requirements and conditions
Singapura
Open cat breed description, care requirements and conditions
Snowshoe
Open cat breed description, care requirements and conditions
Somali
Open cat breed description, care requirements and conditions
Sphynx
Open cat breed description, care requirements and conditions
Thai
Open cat breed description, care requirements and conditions
Tonkinese
Open cat breed description, care requirements and conditions
Toybob
Open cat breed description, care requirements and conditions
Toyger
Open cat breed description, care requirements and conditions
Turkish Angora
Open cat breed description, care requirements and conditions
Turkish Van
Open cat breed description, care requirements and conditions
Bambino
Open cat breed description, care requirements and conditions
Cheetoh
Open cat breed description, care requirements and conditions
Dwelf
Open cat breed description, care requirements and conditions
Elf Cat
Open cat breed description, care requirements and conditions
Genetta
Open cat breed description, care requirements and conditions
Kinkalow
Open cat breed description, care requirements and conditions
Lambkin
Open cat breed description, care requirements and conditions
Serengeti
Open cat breed description, care requirements and conditions
Skookum
Open cat breed description, care requirements and conditions
Ukrainian Levkoy
Open cat breed description, care requirements and conditions