Dog eye discharge and squinting are often signs that the eye is irritated, inflamed, or uncomfortable.
What may be noticed includes watery tears, mucus, or thicker discharge around the eye while a dog blinks repeatedly, partially closes the eyelids, or keeps one eye shut.
The significance depends on whether one or both eyes are affected, how suddenly the symptoms appeared, what the discharge looks like, and whether the eye is red, swollen, cloudy, or painful.
A dog’s age, breed, previous eye problems, recent outdoor activity, and any history of injury can also help determine what may be happening.
Table of Contents
Dog Eye Discharge and Squinting: Why It Happens
Dog eye discharge and squinting can occur when inflammation or irritation affects the conjunctiva, cornea, eyelids, or other structures around the eye.
Increased tearing and discharge can accompany inflammation, while squinting or forcefully closing the eyelids is often a response to discomfort or pain.
Because several different eye disorders can produce similar signs, the combination of discharge and squinting cannot identify the exact cause by itself. In particular, a painful corneal injury can initially look similar to conjunctivitis.
Dog Eye Discharge and Squinting: Common Causes
Corneal Scratch or Ulcer
A corneal scratch or ulcer is an important cause of dog eye discharge and squinting because the cornea is highly sensitive.
Dogs with corneal ulcers often show obvious discomfort, squinting, excessive tearing, or rubbing at the affected eye.
Corneal damage can occur after a scratch, contact with vegetation or another foreign object, or other trauma. Infection can also complicate an existing ulcer.
The eye may become cloudy or develop an unusual appearance. Because deeper ulcers can threaten the integrity of the eye, a painful, persistently squinting eye should not simply be assumed to have ordinary conjunctivitis.
Conjunctivitis
Conjunctivitis, sometimes called pink eye, is inflammation of the conjunctiva, the membrane lining the eyelids and covering part of the eye.
It can cause redness, swelling, increased tearing, discharge, and mild discomfort. Causes include infections, environmental irritants, allergies, foreign material, and other eye conditions.
A dog with conjunctivitis may blink more than usual or squint, although marked or persistent squinting can suggest that something more painful is affecting the eye.
Conjunctivitis affecting only one eye can sometimes be associated with a foreign object, tear-duct problems, or dry eye, while both eyes may be affected with infectious or environmental causes.
Related: Dog mucus eye discharge (Causes and treatment)
Foreign Object or Eye Irritation
Grass, plant material, dust, dirt, or another small foreign object can irritate the eye and cause sudden tearing, discharge, blinking, and squinting.
A foreign object may be particularly likely when symptoms begin suddenly after the dog has been outdoors.
Depending on its location, it can irritate the conjunctiva or scratch the cornea.
If something is lodged in or around the eye, attempting to remove it without knowing where it is located can potentially cause additional injury. Veterinary examination may be needed to identify and safely address the problem.
Related: Dog Eye Discharge and Not Eating and Lethargic (Causes and treatment)
Dry Eye
Dry eye, or keratoconjunctivitis sicca, occurs when inadequate tear production leaves the surface of the eye insufficiently lubricated.
Dogs may develop persistent inflammation, discomfort, and thick or mucus-like discharge.
Dogs with dry eye may squint because the eye surface becomes irritated and painful. Chronic cases can lead to more serious corneal changes if the condition is not appropriately managed.
A veterinarian can assess tear production rather than trying to determine whether a dog has dry eye based only on the appearance of the discharge.
Eyelid Abnormalities
Abnormal eyelid anatomy can cause eyelashes or eyelid hairs to rub against the eye. Conditions such as entropion, in which the eyelid rolls inward, can cause excessive tearing, discharge, squinting, and corneal irritation.
Some dogs have anatomical features that make these problems more likely. Repeated irritation can damage the cornea and potentially contribute to ulcers.
Another eyelid-related condition, distichiasis, occurs when abnormal eyelashes grow from the eyelid margin and contact the eye. It can cause redness, discharge, excessive blinking, and squinting.
Related: Old Dog Eye Discharge (Signs, Causes and treatment)
Eyelid Inflammation
Blepharitis is inflammation of the eyelids. It can cause red or swollen eyelids, itching, discharge, and repeated squinting or blinking. Some dogs rub their faces because the eyelids are uncomfortable.
Blepharitis can have several causes, including infections, allergies, immune-related disease, parasites, trauma, or problems involving nearby structures.
In more severe cases, inflammation can also involve the conjunctiva or cornea.
Allergies or Environmental Irritants
Allergies and environmental irritants can cause watery eyes, redness, and discharge. Dogs may also have itchy skin, paw licking, face rubbing, sneezing, or other signs of allergy.
However, pronounced squinting should not automatically be attributed to allergies.
Significant eye pain is more concerning for conditions involving the cornea or deeper eye structures and warrants veterinary assessment.
Corneal or Other Eye Inflammation
Inflammation involving the cornea or other parts of the eye can produce tearing, discharge, redness, cloudiness, and squinting.
Some forms of corneal inflammation are associated with injury, inadequate tears, eyelid abnormalities, immune-mediated disease, or infection.
These conditions cannot reliably be distinguished at home based solely on the type of discharge or how red the eye appears.
Related: Dog Eye Discharge and Cloudy Eye (Causes and what to do)
Dog Eye Discharge and Squinting in One Eye
When dog eye discharge and squinting affect only one eye, a localized problem becomes an important consideration.
A foreign object, injury, corneal scratch, ulcer, eyelid abnormality, or localized inflammation may affect one eye more than the other.
Conjunctivitis limited to one eye can be associated with foreign material, tear-sac inflammation, or dry eye.
Sudden squinting in one eye, especially after outdoor activity or possible trauma, deserves particular attention because corneal injury may not be obvious without an eye examination.
Dog Eye Discharge and Squinting in Both Eyes
When both eyes have discharge and the dog is squinting, infection, environmental irritation, allergies, inadequate tear production, or other bilateral inflammatory conditions may be considered.
The pattern still does not establish the cause. A veterinarian may need to assess tear production and examine the conjunctiva, eyelids, and corneas to determine why both eyes are uncomfortable.
Dog Eye Discharge and Squinting With a Cloudy Eye
A cloudy or bluish-looking eye together with discharge and squinting is more concerning because corneal swelling, ulceration, or other disorders can alter the normally clear appearance of the cornea.
Corneal disorders can affect vision and may worsen if the underlying problem is not treated.
Immediate attention to corneal disorders is important because the cornea is important for both eye protection and vision.
A cloudy eye should therefore be assessed by a veterinarian rather than treated based solely on the appearance of the discharge.
When to Call or Visit the Vet
Because squinting can indicate eye pain, a dog with persistent eye discharge and squinting should generally be examined rather than monitored indefinitely at home.
Prompt assessment is particularly important when the symptoms appeared suddenly or are getting worse.
Contact a veterinarian immediately if you notice:
Persistent or pronounced squinting
The dog is holding the eye closed
Obvious eye pain or repeated face rubbing
A cloudy, blue, or unusually shaped eye
Significant redness or swelling
Thick or rapidly increasing discharge
Blood in or around the eye
Sudden onset after possible trauma
A suspected foreign object
Changes in vision or difficulty navigating
Swelling of the eyelids
Symptoms that are worsening rather than improving
Persistent symptoms affecting only one eye
A particularly painful eye, rapidly changing eye appearance, or suspected corneal injury warrants prompt veterinary attention because some corneal disorders can progress and affect vision.
Dog Eye Discharge and Squinting: Treatment
Treatment for dog eye discharge and squinting depends on the underlying eye problem.
A veterinarian will examine the eye and may perform tests such as fluorescein staining to look for a corneal scratch or ulcer, tear-production testing to assess for dry eye, and a detailed examination of the eyelids, conjunctiva, and cornea.
Treatment may involve addressing an infection, inflammation, foreign material, inadequate tear production, eyelid abnormality, or corneal injury, depending on the findings.
Eye medications are selected based on the actual diagnosis because different eye conditions require different treatments.
Key Takeaway
Dog eye discharge and squinting usually mean that the eye is irritated, inflamed, or uncomfortable, but the combination does not identify one specific condition.
Conjunctivitis is one possibility, while corneal scratches or ulcers, foreign objects, dry eye, eyelid abnormalities, and other eye disorders can also cause similar signs.
Pay particular attention when squinting is pronounced or persistent. A cloudy eye, significant redness or swelling, obvious pain, sudden onset, changes in vision, or rapidly worsening discharge are reasons for prompt veterinary assessment.
Because some painful eye conditions can threaten the cornea and vision if treatment is delayed, dog eye discharge accompanied by persistent squinting should not automatically be treated as simple conjunctivitis.
A veterinary examination can determine what is causing the discomfort and which treatment is appropriate.