# Why Is My Dog's Eye Watering? Causes and When to Worry Dog eye watering happens when tears spill over the eyelid instead of draining normally through the tear duct system. It can be as harmless as tear staining on a light-colored coat, or it can signal an infection, an allergy, a blocked duct, or a painful scratch on the eye. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - A small amount of clear tearing with no redness, squinting, or swelling is often harmless and can be monitored at home. - Any squinting, pawing at the eye, cloudiness, or a change in eye color needs a same-day veterinary visit. - A sudden thick yellow or green discharge usually means infection or another problem that needs treatment. - A dog that keeps tearing from one eye only may have a blocked tear duct, a foreign body, or a scratch on the cornea. - Never use human eye drops or leftover pet medications in your dog's eye unless your veterinarian prescribed them for this problem. ## What Dog Eye Watering Looks Like and What Is Normal Tears are produced by glands around the eye and by the conjunctiva, the thin membrane that lines the inside of the eyelids and covers the white of the eye [1]. That membrane helps make tears, protects the eye from foreign invaders, and supports healing after a corneal injury [1]. Normal tears drain through small openings at the inner corner of the eye and travel down a duct into the nose. When production outpaces drainage, or when the drainage path is blocked, tears spill onto the face. That overflow is called epiphora. Some tearing is completely normal. Dogs tear more when they are excited, when wind or cold hits their face, or when something irritates the eye. A dog with a small amount of clear moisture at the inner corner, bright eyes, and no squinting is usually fine. What is not normal: - Tears that run constantly down the face and leave a wet or stained track - Redness in the white of the eye - Squinting, blinking hard, or holding the eye closed - Pawing at the face or rubbing the eye on furniture - Cloudiness, a blue tint, or a visible change in the surface of the eye - Discharge that is thick, yellow, green, or sticky If you notice any of these along with the tearing, that moves the problem from cosmetic to medical. ## Common Causes of Dog Eye Watering The table below groups the most common reasons a dog's eye keeps watering, along with the clues that point to each one and how quickly you should act. | Cause | Typical clues | How urgent | |---|---|---| | Environmental irritants (wind, dust, smoke, shampoo) | Both eyes water, no squinting, signs start after exposure | Monitor, usually routine | | Allergies | Both eyes water, redness, itching, often seasonal or with skin itching | Routine visit | | Conjunctivitis (pink eye) | Red eye, swollen tissue around the cornea, discharge, mild discomfort | Same-day to routine, depending on severity | | Blocked tear duct (epiphora) | One eye waters constantly, wet track down the face, no pain | Routine visit | | Corneal ulcer or scratch | Squinting, pawing, tearing from one eye, sensitivity to light | Same day, urgent | | Foreign body (grass awn, hair, grit) | Sudden one-sided tearing, pawing, sometimes visible material | Same day, urgent | | Dry eye (keratoconjunctivitis sicca) | Thick discharge, dull or cloudy eye, recurrent infections | Same day to routine, needs treatment | | Facial nerve dysfunction | Drooping eyelid or lip, reduced tear production, possible corneal ulcer | Same day | | Medication reaction | Tearing starts after a new drug, often with other eye signs | Call your vet promptly | ### Conjunctivitis and Other Surface Problems Conjunctivitis is inflammation of the conjunctiva and is common in dogs [1]. Causes range from infections to environmental irritants, and the signs include redness, swelling of the tissue around the cornea, discharge, and mild eye discomfort [1]. The way the conjunctiva looks is often not enough on its own for your veterinarian to name the cause, so a specific diagnosis may need a medical history, a physical exam, tests on conjunctival scrapings, a Schirmer tear test, and occasionally a biopsy [1]. If your dog's eye is red along with the watering, our guide to [why your dog's eyes are red](/knowledge/veterinary-medicine/symptom-guides/why-are-my-dogs-eyes-red) walks through the common reasons. ### Blocked Tear Ducts and Epiphora A blocked or narrow tear duct is one of the most common reasons for constant tearing without pain. Tears cannot reach the nose, so they spill over the lower eyelid. This often shows up as a wet, reddish-brown stain on the fur below the eye, especially in light-coated breeds. Epiphora by itself is not painful, but the constant moisture can irritate the skin and encourage yeast or bacteria to grow in the damp fur. Your veterinarian can check whether the duct is open and whether the tearing is coming from a drainage problem or from overproduction of tears. ### Dry Eye Can Look Like the Opposite Problem It seems backwards, but some dogs with watery eyes actually have dry eye, also called keratoconjunctivitis sicca or KCS. KCS is an immune-mediated disorder with reduced aqueous tear production, inflammation of the eye surface, and a risk of vision loss [2]. When the tear film is poor quality, the eye produces reflex tears that spill over, so owners see watering instead of dryness. Tear quantity is routinely measured with the Schirmer tear test [2]. In a study of dogs with KCS, total tear protein concentration was significantly higher than in healthy dogs, which shows that tear quality changes along with tear quantity [2]. Some medications can contribute to dry eye. In a large population study, the prevalence of KCS after treatment with trimethoprim sulfonamide was 1.8 percent [3]. If your dog starts tearing or develops a dull eye after a course of antibiotics, tell your veterinarian. ### Facial Nerve Problems The facial nerve controls blinking and eyelid tone. When it does not work properly, the eye can water or, more often, become dry and exposed. In a review of dogs with facial nerve dysfunction, corneal sensitivity and Schirmer tear test values were significantly reduced in affected eyes, and ulcerative keratitis occurred in 61.9 percent of eyes [4]. French Bulldogs were the most frequently affected breed in that group [4]. If one side of your dog's face droops or the eyelid does not close fully, that is a same-day problem. ### Reflex Tearing and Nasal Input Tearing is not only about the eye. Nasal sensory input helps drive reflex tear production. In a study of healthy dogs, numbing one nostril with lidocaine reduced Schirmer tear test values on that side by 11.5 percent in non-brachycephalic dogs, and the reflex tear slope dropped by 21.7 percent [5]. This helps explain why nasal irritation, allergies, and upper airway problems can make a dog's eyes water. ### Chronic Inflammation and the Tear Film Long-standing eye surface inflammation can change the tear film and the meibomian glands, the tiny glands in the eyelids that make the oily part of tears. In a small study of dogs with chronic corneal blood vessel growth, treatment with bevacizumab eye drops was evaluated for its effects on tear composition and meibomian gland function [6]. The point for owners is simple: chronic eye inflammation is not just a surface problem, and it deserves veterinary attention. ## Red Flags That Mean an Emergency Call an emergency clinic or your veterinarian right away if you see any of these: - The eye is suddenly painful, with heavy squinting or the eye held shut - The eyeball looks different, sunken, bulging, or out of place - There is a visible cut, puncture, or foreign object on the eye - The cornea looks cloudy, blue, or white - There is sudden bleeding under the conjunctiva, which can follow trauma, a blood disorder, or certain infectious diseases [1] - Your dog is vomiting, not eating, or acting depressed along with the eye problem - The eye problem started after a fight, a fall, or a chemical exposure Eye pain in dogs is easy to underestimate. A dog that is still eating and wagging its tail can still have a serious corneal ulcer. ## Safe Things You Can Do at Home While You Wait You cannot diagnose the cause at home, but you can avoid making things worse. - Do not put human eye drops, contact lens solution, or leftover antibiotics in your dog's eye. - Do not try to remove a foreign object from the eye surface. You can flush the eye gently with plain saline if your veterinarian tells you to. - Prevent rubbing. An Elizabethan collar or a soft cone can stop your dog from pawing at the eye and causing a scratch. - Keep the area clean. Wipe away discharge with a clean, damp cotton ball, using a fresh one for each eye and wiping away from the eye. - Note the details. Write down when the tearing started, whether it is one eye or both, what the discharge looks like, and any new foods, medications, or exposures. - Check the rest of your dog. If your dog is also not drinking well, see our guide to [a dog not drinking water](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-not-drinking-water-home-care). If the tearing comes with any redness, squinting, or discharge, skip home care and call your veterinarian. ## What Your Veterinarian Will Check and Test Your veterinarian will start with a full eye exam, including the eyelids, conjunctiva, cornea, and the drainage openings at the inner corner of the eye. They will compare both eyes, because one-sided problems often point to a foreign body, a scratch, or a blocked duct. Common tests include: - Schirmer tear test. A small paper strip measures tear production over one minute. Low values point toward dry eye [2][4]. - Fluorescein stain. A yellow dye shows scratches and ulcers on the cornea. - Conjunctival scraping or swab. Cells and discharge are examined to look for infection or inflammation, since the appearance of the conjunctiva alone often cannot identify the cause [1]. - Tear duct flush. A small amount of fluid is placed in the eye to see whether it reaches the nose, which checks for a blockage. - Nasal and airway exam. Because nasal input drives reflex tearing, your veterinarian may look at the nose and upper airway too [5]. - Eye pressure check. This rules out glaucoma, which is painful and urgent. - Blood work. This may be recommended if a generalized disease or medication reaction is suspected. If your dog has thick or colored discharge, our article on [dog eye discharge and when to worry](/knowledge/veterinary-medicine/symptom-guides/dog-eye-discharge-when-to-worry) explains what different types of discharge can mean. Treatment depends on the cause. Bacterial infections need prescription medication. Dry eye needs tear-stimulating or tear-replacement therapy. Blocked ducts may need flushing or surgery. Allergic tearing may improve with antihistamines or by removing the trigger. Your veterinarian will calculate any medication dose from your dog's weight and health, so never guess at a dose yourself. ## Prevention and Monitoring You cannot prevent every eye problem, but you can lower the odds and catch issues early. - Keep hair out of the eyes. Long facial hair can rub the cornea and cause constant tearing. - Rinse after outdoor exposure. A gentle saline flush after hikes or dusty play can remove irritants. - Protect the eyes in the car. Keep your dog's head inside the window to avoid wind, dust, and debris. - Use pet-safe shampoo. Rinse thoroughly and keep suds away from the eyes. - Check eyes weekly. Look for redness, discharge, cloudiness, or a change in the size of the pupils. - Know your breed's risks. Brachycephalic dogs and breeds prone to dry eye or facial nerve problems need closer monitoring [5][4]. - Track medications. If your dog starts a new drug and eye signs appear, call your veterinarian before the next dose. For mild, clear tearing with no other signs, a weekly photo of the eye can help you spot slow changes over time. ## Limitations and When to Contact a Veterinarian This article cannot tell you what is causing your dog's tearing. Only an examination can do that, and individual cases always need a veterinarian. Contact your veterinarian the same day if you see squinting, redness, discharge, cloudiness, a change in eye size, or one eye that is clearly worse than the other. Go to an emergency clinic now if the eye is held shut, the eyeball looks abnormal, there is bleeding under the conjunctiva, or your dog has sudden vision loss or severe pain [1]. Schedule a routine visit if the tearing is clear, painless, and long-standing, especially if it leaves a stain on the fur. Even harmless epiphora is worth checking, because a blocked duct or low tear production can be found early and managed before the eye surface is damaged. ## Frequently Asked Questions ### Is dog eye watering always a sign of a problem? No. Clear tearing with no redness, squinting, or discharge is often normal, especially after wind, excitement, or a small irritant. The tearing matters when it comes with pain, color changes, or a constant wet track on the face. ### Can allergies make my dog's eyes water? Yes. Allergies are a common cause of watery eyes in dogs, and they usually affect both eyes. You may also see redness, itching, and skin or ear problems during the same season. ### What does it mean if only one eye is watering? One-sided tearing often points to a foreign body, a corneal scratch, or a blocked tear duct on that side. Because a scratch can worsen quickly, a one-sided watery eye deserves a veterinary exam. ### Can dry eye cause watery eyes in dogs? Yes. When tear production drops, the eye surface becomes inflamed and produces reflex tears that spill over. A Schirmer tear test is the standard way to measure tear production and confirm the diagnosis [2]. ### Will my dog's watery eye go away on its own? Mild tearing from wind or dust often clears within a day once the trigger is gone. Tearing that lasts more than a day, affects one eye, or comes with redness or squinting needs veterinary care. ## Related Articles - [Dog Eye Discharge: When Should You Worry?](/knowledge/veterinary-medicine/symptom-guides/dog-eye-discharge-when-to-worry) - [Why Are My Dog's Eyes Red?](/knowledge/veterinary-medicine/symptom-guides/why-are-my-dogs-eyes-red) - [Dog Vomiting Clear Liquid: Causes and When to Worry](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-vomiting-clear-liquid) - [What Is Dog Eye Discharge](/knowledge/veterinary-medicine/symptom-guides/what-is-dog-eye-discharge) - [Dog Not Drinking Water: Home Care and When to Worry](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-not-drinking-water-home-care) - [Dog Eye Discharge: What's Normal and When to Call the Vet](/knowledge/veterinary-medicine/preventive-and-routine-care/dog-eye-discharge-normal-when-to-call-vet) - [Why Is My Dog Not Opening One Eye? Causes and When to Worry](/knowledge/veterinary-medicine/symptom-guides/dog-not-opening-one-eye) - [Dog Eye Infection: Symptoms, Treatment, and When to Worry](/knowledge/veterinary-medicine/symptom-guides/dog-eye-infection-treatment) - [Dog Eye Yellow or Green Discharge: Causes and When to Worry](/knowledge/veterinary-medicine/symptom-guides/dog-eye-yellow-green-discharge) ## References 1. [Disorders of the Conjunctiva in Dogs - Dog Owners](https://www.merckvetmanual.com/dog-owners/eye-disorders-of-dogs/disorders-of-the-conjunctiva-in-dogs). Merck Veterinary Manual. 2. [Tear Protein Alteration in Dogs with Keratoconjunctivitis Sicca](https://pubmed.ncbi.nlm.nih.gov/41594350/). Animals : an open access journal from MDPI, 2026. 3. [Retrospective cohort study on the development of keratoconjunctivitis sicca in dogs treated with trimethoprim sulfonamide: a VetCompass Australia study](https://pubmed.ncbi.nlm.nih.gov/41742488/). Journal of veterinary internal medicine, 2026. 4. [Ocular Manifestations in Dogs With Facial Nerve Dysfunction](https://pubmed.ncbi.nlm.nih.gov/42385198/). Veterinary ophthalmology, 2026. 5. [Beyond the Ocular Surface: Nasal Sensory Input as a Driver of Reflex Lacrimation in Dogs](https://pubmed.ncbi.nlm.nih.gov/41204707/). Veterinary ophthalmology, 2026. 6. [Topical Application of Preserved and Unpreserved Bevacizumab Eye Drops Improves Ocular Surface Parameters in Dogs with Chronic Keratitis: A Pilot Study](https://pubmed.ncbi.nlm.nih.gov/42076760/). Veterinary sciences, 2026. ## Further Reading - [Merck Veterinary Manual: Dog Owners](https://www.merckvetmanual.com/dog-owners) - [Cornell Richard P. Riney Canine Health Center: Canine Health Information](https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/canine-health-information) - [American Veterinary Medical Association: Pet Care](https://www.avma.org/resources-tools/pet-owners/petcare)