Cat Watery Eyes and Tear Staining: What the Overflow Actually Means

Quick answer

Tear staining is not a disease. It is the visible residue of tears that ran down the face instead of draining into the nose, and the useful question is always why they overflowed.

There are only two possible answers. Either the eye is making more tears than normal, which means something is irritating or hurting it, or the drainage route is blocked or malformed, which means the tears have nowhere else to go. Those two situations look identical on the fur and are managed completely differently.

A calm handling routine is what lets you look at both eyes properly rather than guessing from across the room.

• The reddish-brown colour comes from pigments in tears that darken on exposure to air and light. It is not rust, dirt or infection.
• Overflow in both eyes in a flat-faced breed is usually anatomy. Overflow in one eye in an adult cat is usually a problem.
• Squinting, a raised third eyelid or a cloudy surface changes this from a cosmetic issue into a same-day one.
• Clean with plain saline or lukewarm water, and dry the fur afterwards.
• Never put steroid eye drops in a cat's eye without a vet first staining the cornea.

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A cat that is holding one eye shut, pawing at its face or avoiding light has a painful eye, and a painful eye is an emergency in this species.

Cats hide pain well, so visible discomfort in the eye means significant damage. Corneal ulcers can progress from a surface scratch to a perforation in a day or two, and feline herpesvirus can produce ulcers that spread across the surface rather than staying as a single defect. Steroid drops applied to an ulcerated cornea accelerate the destruction of the tissue and can cost the eye. Nothing goes in that eye until a vet has stained it.
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Decide in 60 seconds

Why tears end up on the face

Tears are made continuously, spread across the eye by blinking, and then pulled into two pinhole openings called puncta at the inner corner of each lid. From there they run through the nasolacrimal duct, through a channel in the skull, and out into the nose. That is why a cat with a healthy face never appears to be crying: the tears leave through the nose and you never see them.

Overflow happens when either end of that system fails.

Too much tear production.

Anything that irritates the eye increases tear volume beyond what the duct can carry. Conjunctival infection, a corneal ulcer, a foreign body under the third eyelid, an inward-rolling eyelid rubbing the surface, a scratch from another cat, dust and aerosols, and inflammation inside the eye all do this. In every one of these the tearing is a symptom and the eye is uncomfortable.

Failure of drainage.

The tears are normal but cannot leave. In flat-faced breeds the skull is compressed, the duct is shortened and kinked, and the eye sits in a shallow socket so that the lids do not sit against the globe in the way that directs tears to the puncta. Many of these cats also have a fold of skin at the inner corner with hair that touches the eye and wicks tears out onto the face like a cotton thread.

Drainage also fails after damage. Kittens infected with feline herpesvirus can develop severe conjunctivitis before or shortly after the eyes open, and the healing process fuses tissue and scars the puncta and duct closed. Those cats are then wet-faced for life through no current disease at all. Trauma, chronic inflammation and tumours in older cats can block the duct too.

Pressure from outside the duct.

The upper carnassial and canine tooth roots sit close to the duct's path through the skull. An abscess or advanced periodontal disease at those roots can compress the duct, and the first thing an owner notices is a runny eye on that side with no eye problem at all.

What normal and abnormal look like

A healthy cat's eyes are open to the same width, the corneas are clear enough that the iris pattern is crisp, the whites are not pink, and there is at most a small amount of dark crust in the inner corner in the morning.

Handling the head calmly lets you compare both sides. Symmetry is the single most informative thing you can look for.

Compare the two sides deliberately, because a slow change on one side is invisible unless you look for it. Are the eyes the same width open. Is the third eyelid, the pale membrane at the inner corner, showing on one side only. Is the pupil the same size. Is the fur under one eye wetter than the other.

The staining itself tells you about duration rather than severity. Pigments in tears darken with air and light, so a deep reddish-brown streak means tears have been running there for a while. Freshly wet fur with no colour means the overflow is recent.

Colour and texture of the discharge sort the causes. Clear and watery is overflow, early irritation or a viral conjunctivitis. Mucoid and stringy suggests ongoing inflammation. Yellow, green or grey suggests bacterial involvement, often secondary to something else. Any blood is significant.

Changes that mean act today

A squint that was not there yesterday.

Cats squint when the eye hurts. Combined with tearing it means a corneal problem until a fluorescein stain says otherwise.

The third eyelid crossing the eye.

This membrane comes across when the eye is painful, when the globe has sunk from dehydration or pain, or when there is a nerve problem. It is never a normal resting position in a comfortable cat.

Cloudiness, haze or a blue tint.

Corneal oedema. It means the surface barrier is damaged and fluid is entering the cornea.

Sudden onset in one eye in an adult.

One-sided problems are anatomical only if they have been there for years. New one-sided tearing points to a foreign body, an ulcer, a duct blockage or a dental cause.

Tearing plus sneezing, nasal discharge or a reduced appetite.

Feline upper respiratory disease. It is contagious to other cats in the house, and a cat that stops eating because it cannot smell food needs help sooner than one that is simply snuffly.

Swelling under or beside the eye.

Think tooth root abscess, and expect the vet to want dental radiographs rather than just eye drops.

The routine that keeps the face healthy

Cleaning is worth doing, but its purpose is skin health rather than appearance. Tears sitting in a warm facial fold soften the skin and feed yeast and bacteria, and a moist dermatitis in that fold is itchy and smelly and much harder to treat than the original tearing.

Sterile saline, soft pads and a dry cloth are the whole kit. Everything else is optional and most of it is unhelpful.

Use sterile saline or clean lukewarm water on a soft pad. Use a separate pad for each eye so that an infection in one is not carried to the other. Wipe from the inner corner outwards and downwards, following the direction the tears already run, rather than towards the eye.

Then dry. A second soft dry pad or cloth over the damp fur is the step that actually prevents the skin problem, and it is the step most people skip.

Keep the hair at the inner corner short if your vet or groomer is comfortable doing it, and let them do it. Scissors next to a cat's eye in a moving cat is how corneal lacerations happen.

Do this daily for a cat with constant overflow and after any flare-up in a cat that is usually dry. If the fur under the eye is chronically damp, red or smells, that is a skin problem to show a vet rather than to scrub harder.

What never to do

Do not use human eye drops that reduce redness. They work by constricting blood vessels, they mask the inflammation a vet needs to see, and they do nothing for the underlying cause.

Do not use steroid-containing drops, even ones prescribed for a previous eye problem in the same cat, without a fresh examination. A steroid on an ulcerated cornea can turn a treatable defect into a lost eye.

Do not use drops prescribed for another animal, or for a different episode months ago. Bottles become contaminated once opened and the diagnosis has probably changed.

Do not flush the eye with anything other than sterile saline. Not baby shampoo, not tea, not diluted disinfectant, not colloidal silver.

Do not pluck hair from the inner corner or trim it with the cat unrestrained.

Do not accept "it is just staining" for a cat that is squinting, and do not wait to see whether a cloudy eye clears on its own.

When to get help

Book a routine appointment for longstanding, comfortable, both-sided overflow in a flat-faced cat, so the cornea and lids are checked once and you know what you are managing.

Book within a day or two for new tearing with sneezing or nasal discharge, for thick coloured discharge, or for damp red skin under the eye.

Go the same day for squinting, a raised third eyelid, cloudiness, pawing at the eye, light sensitivity, or new tearing in one eye only.

Go immediately for blood, a bulging or sunken eye, obvious injury, or a cat that will not open the eye at all.

A comfortable cat with two equally open, clear eyes is the endpoint. The stain is cosmetic; the comfort is not.

Bring the date the tearing started, whether it is one eye or both, the colour of the discharge, whether the cat has had cat flu or lives with other cats, its vaccination history, everything you have already put in or near the eye, and your weekly photographs. Expect a fluorescein stain to check for ulcers, an examination of the lids and third eyelid, and depending on findings a tear duct flush, tests for herpesvirus and chlamydia, or dental radiographs.