SYMPTOM
Excessive tearing
Owners may observe excessive tearing in their pet.
Various conditions
This symptom can occur in multiple conditions and warrants further assessment.
Nasolacrimal Duct Obstruction
Tears normally drain from the eye into the nose through a narrow duct, and when this pathway is blocked or simply too shallow to drain efficiently, tears overflow onto the face instead. Brachycephalic breeds such as Persians, British Shorthairs, Pugs and Shih Tzus have a naturally shortened, less efficient drainage system as a result of their skull shape, making this a common and largely anatomical explanation in these breeds.
Conjunctivitis
Inflammation of the membrane covering the eye and lining the lids increases reflex tear production as the eye responds to the irritation. Viral, bacterial and allergic causes are all recognised in both species, and the tearing is usually accompanied by some redness or mild discharge.
Entropion
Inward rolling of the eyelid margin brings the surrounding hair into continuous contact with the corneal surface, generating ongoing reflex tearing as the eye responds to this irritation. It is particularly recognised in breeds with loose facial skin such as Shar Peis and Chow Chows, and in cats it is less common but does occur, especially where facial conformation is flat.
Glaucoma
A rise in pressure within the eye is painful and stimulates reflex tear production alongside other signs such as a cloudy or enlarged appearance to the eye. It can develop primarily or secondary to other eye disease, and certain breeds, including Cocker Spaniels and Basset Hounds, carry a recognised predisposition.
Environmental Irritants and Allergies
Dust, pollen, smoke, or strong household products can trigger reflex tearing in an otherwise healthy eye simply through surface irritation, without any underlying eye disease being present. This tends to affect both eyes evenly and to vary with exposure, easing once the irritant is removed.
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
Reflex tear production increases in response to corneal irritation and injury.
Uveitis
Watery ocular discharge commonly accompanies uveitis.
Distichiasis
Constant lash contact with the corneal surface stimulates the tear glands to produce more fluid than usual.
Ectopic Cilia
Direct contact between the errant hair and the corneal surface triggers a strong reflex tearing response.
Ectropion
A sagging lower lid disrupts the normal tear drainage pathway, so tears pool and overflow down the face.
Facial Nerve Paralysis
Because the eyelid can no longer blink normally, tears are not spread across the eye properly and it becomes watery and irritated.
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