SYMPTOM
Painful red eye
Owners may observe painful red eye in their pet.
Various conditions
This symptom can occur in multiple conditions and warrants further assessment.
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
Glaucoma
Elevated intraocular pressure causes intense scleral injection and significant pain.
Feline Herpesvirus (FHV-1)
Feline herpesvirus type 1 often causes conjunctivitis and corneal ulceration, which can present as redness, discharge, and visible discomfort in one or both eyes. The inflammation may be unilateral or bilateral and tends to recur during periods of stress or immune suppression.
Feline Calicivirus
Feline calicivirus can cause conjunctivitis alongside respiratory signs, leading to red, inflamed eyes with discharge and squinting. The ocular signs typically occur as part of a broader respiratory presentation.
Dental Disease in Dogs
Dental disease in dogs may cause referred pain or localised infection that extends to nearby structures, occasionally resulting in swelling or inflammation around the eye if periorbital tissues become involved. This tends to occur when infection tracks from dental roots, particularly those of the upper fourth premolar.
Dental Disease in Cats
Dental disease in cats can lead to periorbital swelling and ocular discharge when dental infection extends rostrally or dorsally from tooth roots, particularly the upper carnassial. The eye may appear red and painful as a secondary consequence of the underlying oral pathology.
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