Cats tear up when their eyes produce more fluid than their tear ducts can drain, or when those ducts are blocked and tears spill over onto the face. This overflow, called epiphora, is one of the most common eye-related concerns cat owners notice. The causes range from a simple irritant to a chronic infection, and the color and consistency of the discharge often tells you a lot about what’s going on.
How Tear Drainage Works in Cats
A thin film of tears constantly coats your cat’s eyes to keep them lubricated and flush out debris. Excess fluid normally drains through tiny tear ducts in the inner corner of each eye, near the nose. Those ducts funnel tears into the back of the sinuses and down the throat, so under normal conditions you never see the fluid at all. Tearing becomes visible when something causes overproduction of tears, blocks the drainage pathway, or both.
Viral and Bacterial Infections
Feline herpesvirus (FHV-1) is one of the most common culprits behind watery, irritated eyes. The virus targets cells in the conjunctiva, nasal lining, and cornea, causing rapid cell damage that leads to inflammation. Symptoms typically appear two to six days after infection and include redness, swelling, and a watery discharge that may start clear and become thicker over time. In more severe cases, the virus causes tiny ulcers on the surface of the eye that can persist for weeks. FHV-1 can also reduce tear film quality long-term, creating a cycle where the eyes are simultaneously too dry (unstable tear film) and too watery (reflex tearing from irritation).
Bacterial infections matter too. Chlamydia felis, an intracellular bacterium, causes conjunctivitis with red, swollen, painful eyes and sometimes purulent discharge. It often starts in one eye and spreads to the other. Feline calicivirus and Mycoplasma species can also trigger conjunctivitis with tearing, though they’re less frequently the sole cause of eye symptoms.
Physical Irritants and Eyelid Problems
Anything that irritates the surface of the eye triggers reflex tearing. Dust, smoke, household chemicals, and stray hairs are common offenders. But in some cats, the irritant is structural. Entropion is a condition where the eyelid rolls inward, pushing the lashes against the cornea. The constant friction causes pain, squinting, chronic conjunctivitis, and eventually corneal ulcers or scarring if left untreated. Cats with entropion often look like they’re perpetually squinting, and the affected eye tears heavily. Surgical correction has a high success rate, but without treatment the prognosis is poor.
Foreign bodies lodged under the third eyelid are another frequent cause. A small piece of plant matter or grit can sit hidden against the eye surface, causing localized ulceration and heavy tearing that won’t resolve until the object is removed.
Flat-Faced Breeds and Blocked Tear Ducts
Persians, Himalayans, Exotic Shorthairs, and other flat-faced breeds are practically guaranteed to have some degree of tearing. Their compressed skull geometry distorts the path of the tear ducts so severely that drainage into the nasal cavity is minimal at best. Tears stream down the front of the face instead, leaving rusty-brown stains on the fur and sometimes causing skin irritation or dermatitis in the folds beneath the eyes.
Tear duct blockages aren’t exclusive to flat-faced cats, though. Any cat can develop an obstruction from chronic inflammation, a tooth root abscess (particularly involving the upper canine teeth), or even a congenital narrowing present from birth. Some kittens show signs of blocked ducts as early as one month of age. Vets typically try to flush the duct with saline to restore flow. When flushing fails, surgical options exist to reroute drainage into the nasal cavity or sinuses.
What the Discharge Color Tells You
Clear, watery discharge usually points to irritation, allergies, or the early stage of a viral infection. It’s the least alarming type but still worth monitoring if it persists for more than a day or two. When discharge turns yellow or green and thickens to a mucus-like consistency, a bacterial infection is likely involved, either as the primary problem or as a secondary infection layered on top of a viral one. Brownish or rust-colored staining, especially in flat-faced breeds, typically reflects normal tears that have oxidized on the fur rather than an active infection.
Signs That Need Prompt Attention
Some tearing is minor and resolves on its own. Other presentations signal something that can threaten your cat’s vision. Thick yellow-green discharge, visible blood in or around the eye, and rapid cloudiness developing over hours rather than days all fall into the urgent category. A cat that holds one eye tightly shut, paws at its face repeatedly, or stops eating because of discomfort is telling you the pain is significant. Unequal pupil sizes, protrusion of the third eyelid, or pronounced swelling around the eye socket also warrant immediate care. These signs can indicate deep corneal ulcers, glaucoma, or trauma that worsens quickly without treatment.
How Vets Identify the Cause
The diagnostic workup for a tearing cat is usually straightforward. A fluorescein stain test is one of the first steps: a drop of fluorescent dye is placed on the eye’s surface and viewed under a blue light. The dye sticks to exposed layers of the cornea, so any ulcer lights up clearly. The same dye can be used to check tear duct function. If the dye appears at the cat’s nostril within a few minutes, the duct is open. If it doesn’t, there may be a blockage.
A Schirmer tear test measures actual tear production by tucking a small paper strip under the lower eyelid for one minute. This helps distinguish cats that are tearing excessively from those whose tear film is unstable, causing compensatory overflow. For suspected infections, swabs can be taken for bacterial culture or PCR testing to identify specific viruses like FHV-1.
Managing Ongoing Tearing
Treatment depends entirely on the cause. Bacterial conjunctivitis from Chlamydia felis typically responds well to a course of oral antibiotics over two to four weeks. Viral infections like FHV-1 are trickier because the virus establishes lifelong latency, meaning it can reactivate during periods of stress. Antiviral eye drops or ointments help manage flare-ups, but there’s no permanent cure. Keeping stress low, maintaining good nutrition, and staying current on vaccinations all reduce the frequency of episodes.
For structural problems like entropion, surgery is the definitive fix. Flat-faced breeds with chronic tear overflow benefit from daily cleaning of the fur beneath the eyes to prevent staining and skin breakdown. A damp cloth or pet-safe wipe works well for this. Blocked tear ducts that can be flushed open sometimes stay open afterward, but some cats need repeated procedures or permanent surgical rerouting.
Simple irritant-based tearing often resolves once the trigger is removed. Switching to a dust-free litter, avoiding aerosol sprays near your cat, and checking for stray hairs near the eyes are easy first steps if the discharge is clear and your cat seems otherwise comfortable.