SYMPTOM
Eye discharge
Owners may observe eye discharge in their pet.
Various conditions
This symptom can occur in multiple conditions and warrants further assessment.
Feline Viral Upper Respiratory Infection
Herpesvirus and calicivirus infection inflame the conjunctiva, producing clear to mucopurulent discharge alongside sneezing and mild ocular discomfort. Kittens and cats in multi-cat households have the highest exposure, and herpesvirus in particular tends to recur through life during periods of stress.
Corneal Ulceration
Damage to the corneal surface triggers reflex tearing, which becomes thicker and discoloured if secondary bacterial infection sets in. Common causes include trauma, foreign material trapped under the third eyelid, and eyelid conformation issues that allow hair or lashes to contact the cornea.
Allergic or Irritant Conjunctivitis
Airborne allergens, dust, pollen, and grooming products can inflame the conjunctiva and increase tear production, usually affecting both eyes evenly. This pattern is more common in dogs than cats and often follows a seasonal rhythm linked to pollen counts.
Nasolacrimal Duct Obstruction
When the tear drainage channels running from eye to nose narrow or become blocked, tears overflow onto the face instead of draining normally, producing facial staining rather than a true discharge. Brachycephalic breeds such as Persians, Pekingese, and Shih Tzus are predisposed because of their facial and duct conformation.
Eyelid and Eyelash Conformation
Entropion, ectopic cilia, and distichiasis cause low-grade mechanical irritation from hair or eyelid margin rubbing against the eye, producing a chronic mild discharge rather than an acute infection. These conformational traits run in breeds including Shar Peis, Cocker Spaniels, and Persians and are often present from a young age.
Why timing matters
Early observation
Early recognition allows prompt assessment and intervention if needed.
Later presentation
Persistent or worsening signs may indicate progression requiring attention.
The significance of this symptom depends on its context, duration, and associated findings.
Conditions commonly associated
Corneal Ulcers
Mucoid or purulent discharge may develop, particularly with secondary infection.
Feline Herpesvirus (FHV-1)
Conjunctivitis and corneal involvement cause watery to mucoid discharge from affected eyes.
Eosinophilic Keratitis in Cats
Irritation of the cornea in eosinophilic keratitis typically produces ongoing discharge from the affected eye.
Conjunctivitis
Inflammation of the delicate membrane covering the eye and lining the lids increases tear production and mucus, leading to visible discharge.
Keratoconjunctivitis Sicca (Dry Eye)
Reduced tear film production allows the ocular surface to dry and become irritated, prompting the eye to produce thick, sticky mucoid discharge in compensation.
Entropion
Inward rolling of the eyelid causes the surrounding hair to continuously rub the surface of the eye, irritating it and stimulating excess tear and mucus production.
Feline Calicivirus
This common feline respiratory virus inflames the conjunctiva and upper airway, producing ocular discharge alongside sneezing and mouth ulcers.
When to explore further
When the symptom is persistent or worsening
When other signs are present alongside
When daily activities or quality of life are affected
When there is uncertainty about the cause
Noting when this symptom occurs, any triggers, and how it changes over time can provide useful information for veterinary discussions.
Last reviewed: 24 April 2026 · Dr Alastair Greenway MRCVS