Watery eyes in cats are usually caused by irritation, infection, or a drainage problem that prevents tears from flowing where they should. Tears normally form a thin protective film over the cornea made of water, oil, and mucus. When something irritates the eye or blocks the drainage path, tears overflow onto the face, a condition vets call epiphora. The cause can be as minor as a speck of dust or as serious as a viral infection, so the type of discharge and any accompanying symptoms matter a lot.
How Tear Drainage Works in Cats
A healthy cat’s eyes produce tears constantly to wash away debris and keep the corneal surface smooth. Excess tears drain through tiny openings near the inner corner of each eye, travel down a narrow channel called the nasolacrimal duct, and empty into the nose. That’s why a crying human gets a runny nose, and the same plumbing exists in cats.
Watery eyes happen in one of two ways: either the eyes produce more tears than the drainage system can handle, or the drainage system itself is partially or fully blocked. Both routes lead to the same visible result, tears spilling down the face, but the underlying cause and treatment are different.
Upper Respiratory Infections
Feline herpesvirus (FHV-1) is the single most common infectious cause of watery eyes in cats. Roughly half of all cats carry this virus, and once infected, a cat carries it for life. The virus can reactivate during periods of stress, illness, or immune suppression.
During a primary infection, especially in kittens and young cats, symptoms appear after a 2 to 6 day incubation period. You’ll typically see watery discharge from both eyes along with sneezing, nasal discharge, reduced appetite, and fever. Over several days the discharge often shifts from clear and watery to thick, yellow, or greenish as secondary bacterial infection sets in. Herpesvirus can also cause inflammation of the cornea, leading to squinting, sensitivity to light, and more tearing.
Feline calicivirus, another common upper respiratory pathogen, can produce similar symptoms, though it tends to affect the mouth and airways more than the eyes.
Corneal Injuries and Ulcers
A scratch from another cat, a poke from a branch, or even a trapped piece of debris can damage the cornea’s surface. The eye responds by flooding the area with tears. Signs of a corneal ulcer include cloudiness over the affected eye, visible discharge, squinting, pawing at the face, and light sensitivity. Cats with ulcers often hold the injured eye partially or fully shut.
Vets diagnose corneal damage using an orange dye called fluorescein. A small strip of blotting paper containing the dye is touched to the eye’s surface. Under blue light, any damaged area glows green, revealing the exact size and location of the ulcer. The shape and position of the stained area help determine whether the injury was caused by trauma, infection, or a structural problem like an inward-turning eyelid.
Flat-Faced Breeds and Tear Staining
Persians, Exotic Shorthairs, and Himalayans are especially prone to chronic watery eyes, and their facial structure is the reason. Brachycephalic (flat-faced) breeds have shortened muzzles that distort the normal path tears take from the eye to the nose. Tears can’t enter the drainage duct properly, so they simply roll down the face, leaving rusty brown staining on the fur below each eye.
These breeds also have more protruding eyes because of the shape of their skulls, and their eyelids sometimes can’t close completely. That combination leaves more of the corneal surface exposed to air and irritants, which triggers more tear production on top of the drainage problem. For these cats, some degree of tearing is a lifelong reality rather than a sign of acute illness. Regular gentle cleaning of the fur below the eyes helps prevent skin irritation and infection in the folds.
Blocked Tear Ducts
Even in cats without flat faces, the nasolacrimal duct can become narrowed or blocked. Known causes include tooth root abscesses (especially involving the upper canine teeth), severe inflammation after a dental extraction, and in rare cases, tumors near the duct. Some cats are born with a duct that never fully developed, which means tearing starts very early in life, sometimes within the first month.
Chronic herpesvirus infections can also scar and narrow the duct over time. To check for a blockage, vets flush saline through the duct opening. If the fluid doesn’t flow freely into the nose, imaging (usually a CT scan with contrast dye) can pinpoint where and why the duct is obstructed.
Allergies and Environmental Irritants
Cats can develop allergic reactions to many of the same triggers humans deal with: pollen, grass, mold, mildew, and dust mites. These allergies sometimes produce respiratory symptoms like coughing, sneezing, and wheezing, along with watery or slightly mucousy eye discharge. The tearing tends to affect both eyes equally and often follows a seasonal pattern if pollen is the trigger.
Household irritants are another common culprit. Cigarette smoke, strong cleaning products, scented candles, perfumes, and aerosol sprays can all irritate a cat’s eyes enough to cause excess tearing. If you notice your cat’s eyes water mainly after you clean the house or light a candle, the product itself is likely the problem. Switching to unscented or pet-safe alternatives usually resolves it.
Eyelid and Eyelash Problems
Structural issues around the eye can cause ongoing irritation and tearing. Entropion is a condition where the eyelid rolls inward, pressing fur and skin against the cornea with every blink. Distichiasis and trichiasis are conditions where eyelashes or facial hairs grow in the wrong direction, rubbing against the eye’s surface. All three create chronic irritation that triggers a steady overflow of tears and, if left untreated, can lead to corneal ulcers.
What the Discharge Tells You
The color and consistency of your cat’s eye discharge is a useful clue. Clear, watery discharge typically points to irritation, allergies, or early-stage infection. It’s also what you see with blocked tear ducts and breed-related drainage issues. Yellow or green discharge signals bacterial involvement, either as a primary infection or a secondary infection layered on top of a viral one like herpesvirus. Thick, crusty discharge that seals the eyelids shut, particularly in kittens, usually indicates an active upper respiratory infection that needs treatment.
Signs That Need Prompt Attention
Mild, clear tearing in one eye that resolves within a day or two is usually nothing to worry about. But certain symptoms suggest something more serious is going on. A cloudy or hazy appearance to the eye, persistent squinting or holding the eye shut, red and swollen tissue around the eye, visible pain (flinching when the area is touched, hiding, or loss of appetite), and discharge that has turned yellow or green all warrant a veterinary visit sooner rather than later. Cloudiness combined with squinting and head rubbing is a classic presentation of a corneal ulcer, which can worsen rapidly without treatment.
If only one eye is affected, trauma or a foreign body is more likely. If both eyes are watering along with sneezing and nasal discharge, infection is the probable cause. Noting these details before you call the vet helps them triage the situation more quickly.