Eye Infections in dogs: What you need to know
Redness, discharge, or squinting may look like a simple eye infection, but several different eye problems can cause the same symptoms. Here’s how to recognize the warning signs, what veterinarians look for, and when your dog’s eye needs prompt attention.
Updated August 20, 2026 at 2:22 PM ET
Because eye problems can worsen quickly and some can threaten vision, contact your veterinarian when your dog develops persistent redness, unusual discharge, squinting, swelling, cloudiness, or obvious eye pain.
What Does a Dog Eye Infection Look Like?
You may first notice something small.
Your dog has more eye discharge than usual. One eye looks red. They keep blinking. Maybe they are rubbing their face against the couch or trying to paw at the eye.
Those symptoms deserve attention, but they do not tell you exactly what is wrong.
Possible signs of an eye problem include:
- Red or pink tissue around the eye
- Yellow, green, or mucus-like discharge
- Excessive tearing
- Swollen eyelids or tissue around the eye
- Frequent blinking
- Squinting or keeping the eye closed
- Pawing or rubbing at the eye
- Sensitivity to light
- A raised or unusually visible third eyelid
- Cloudiness or a change in the appearance of the cornea
The important distinction is that these are signs of an eye problem, not proof of infection.
The Merck Veterinary Manual notes that conjunctivitis—the inflammation many owners associate with pink eye—can have infectious and noninfectious causes. A veterinarian may need more than the appearance of the eye alone to determine what is actually happening.
Is It Really an Eye Infection?
This is one of the most important distinctions to understand.
When we see discharge and redness, infection feels like the obvious explanation. But several conditions can look remarkably similar from the outside.
An infection occurs when an infectious organism is involved in disease of the eye or surrounding tissues. Bacteria can be involved, but an eye can also become inflamed because something else went wrong first.
For example, a dog may scratch the cornea. Bacteria can then complicate that injury. In that situation, treating only what appears to be an infection without recognizing the damaged cornea misses the larger problem.
Merck notes that bacterial infection can complicate corneal ulcers and that many ulcers originate from mechanical injury such as scratches or foreign objects.
Common Causes of Red, Irritated, or Discharging Eyes
Conjunctivitis
Conjunctivitis means inflammation of the conjunctiva, the thin membrane lining portions of the eyelids and front of the eye.
It can cause redness, swelling, discharge, and discomfort.
But conjunctivitis describes inflammation, not a single cause.
Infections can cause it, but so can environmental irritants, allergens, foreign material, tear-related problems, and abnormalities involving the eyelids.
Corneal Scratches and Ulcers
The cornea is the transparent front surface of the eye.
A dog can injure it by running into vegetation, getting debris in the eye, being scratched, rubbing the face, or experiencing another form of trauma.
Corneal ulcers can be painful. Signs may include tearing, squinting, blinking, and changes in the appearance of the cornea.
This is one reason it is risky to treat every red eye as though it is automatically pink eye. A corneal injury can sit underneath symptoms that initially look very similar.
Veterinarians can use fluorescein dye to help identify corneal ulcers that may otherwise be difficult to see.
Dry Eye
Dogs can develop keratoconjunctivitis sicca, commonly called dry eye or KCS.
Tears do far more than make the eyes wet. They help protect and maintain the surface of the eye.
When tear production becomes inadequate, thick mucus and irritation can develop. The altered environment may also make secondary infection more likely.
Because symptoms can include discharge and redness, dry eye can easily be mistaken for a routine infection without proper testing.
Allergies and Environmental Irritants
Pollen, dust, and other environmental exposures may contribute to eye irritation or conjunctivitis.
Shampoo, smoke, debris, and other irritants can also make an eye red or watery.
This is another reason redness alone cannot identify the cause.
Foreign Material
Dogs investigate the world face-first.
Grass, dirt, plant material, and tiny pieces of debris can become trapped around the eye. A foreign object can irritate the conjunctiva or damage the cornea.
If your dog suddenly begins squinting or pawing at one eye after playing outside, do not automatically assume the problem will simply wash itself out.
Eyelid Problems
Sometimes the problem is not the eyeball itself.
The anatomy of a dog's eyelids can expose or irritate the eye. Some dogs cannot completely close their eyelids, while others have eyelid conformations that allow hairs or tissue to repeatedly irritate the surface.
Merck notes that brachycephalic dogs—including Bulldogs and Pugs—can be affected by lagophthalmos, an inability to completely close the eyelids and adequately protect the cornea.
Trauma
Scratches, collisions, fights, sticks, and other injuries can damage delicate eye structures.
Eye trauma deserves particular respect because the extent of the damage is not always obvious from the outside.
What Does Eye Discharge Color Mean?
Owners naturally look at discharge color for clues.
Clear or Watery Discharge
Clear tearing can occur with irritation, allergies, pain, foreign material, and several eye disorders.
It does not automatically mean allergies.
Thick or Mucus-Like Discharge
Thicker mucus may occur when normal tear function is disrupted, including in dogs with dry eye.
Yellow or Green Discharge
Yellow or green discharge can occur when inflammatory cells and bacteria are present.
That makes infection an important possibility, but color still cannot tell you whether there is an underlying ulcer, dry eye, foreign object, or another condition contributing to the problem.
One Eye vs. Both Eyes
Whether one or both eyes are affected can give a veterinarian useful information, although it still does not establish a diagnosis by itself.
A sudden problem affecting only one eye can increase concern about local causes such as:
- Trauma
- A foreign object
- A corneal injury
- Tear drainage problems
- Certain forms of dry eye
Problems involving both eyes may make a veterinarian consider broader environmental, allergic, infectious, or systemic causes.
When Is a Dog Eye Problem an Emergency?
Not every watery eye requires an emergency hospital.
But eyes are not a good place for a long wait-and-see experiment when your dog is clearly uncomfortable.
- Significant squinting or inability to open the eye
- Sudden cloudiness
- An obvious wound or eye injury
- Blood in or around the eye
- A foreign object that appears embedded
- A major change in eye shape or position
- Sudden apparent loss of vision
- Severe swelling
- Significant pain
- Rapidly worsening symptoms
Corneal disease deserves particular attention because deep ulcers can progress through the thickness of the cornea.
Even when the situation does not look dramatic, persistent redness, discharge, or discomfort deserves a call to your veterinarian.
Vision is too important to gamble on guessing correctly.
How Veterinarians Diagnose Dog Eye Problems
A good eye examination is about determining why the eye is irritated, not merely confirming that it looks red.
Fluorescein Stain
A fluorescent dye can highlight damage to the corneal surface and help identify an ulcer.
Tear Production Testing
A Schirmer tear test can help evaluate whether your dog is producing enough tears.
Eye Pressure
Measuring pressure inside the eye can help veterinarians investigate conditions in which abnormal intraocular pressure may be important.
Foreign Material and Structural Problems
The veterinarian may examine the eyelids, conjunctiva, cornea, and surrounding structures for foreign material, abnormal anatomy, trauma, or other disease.
Additional Testing
Some cases require cytology, cultures, or other diagnostic tests, particularly when symptoms are persistent, severe, or unusual.
The treatment decision comes after the cause is investigated.
How Are Dog Eye Infections Treated?
There is no single universal dog eye infection medicine.
Treatment depends on the diagnosis.
A bacterial infection may require antimicrobial medication. A corneal ulcer may require topical medication and management of the underlying injury. Dry eye may require long-term treatment designed to improve tear production and protect the ocular surface. Foreign material may need to be removed. Certain structural problems can require surgical correction.
This is why grabbing leftover eye drops from a previous problem is not a good plan.
The medication that was appropriate for one eye condition may be inappropriate for another.
Can I Treat My Dog's Eye Infection at Home?
You can help prevent your dog from rubbing or further injuring the eye while arranging veterinary care, but you should not diagnose and medicate a suspected eye infection yourself.
Avoid:
- Human eye medications unless specifically directed by your veterinarian
- Old prescription drops left over from another episode
- Medication prescribed for another pet
- Random antibiotic products
- Putting non-sterile substances into the eye
Some eye medications contain corticosteroids. These medications have legitimate veterinary uses, but the presence of a corneal ulcer can completely change the treatment decision.
That is precisely why having the eye examined first matters.
Should You Clean Your Dog's Eye Discharge?
You can gently clean discharge from the fur surrounding the eye when necessary, but do not scrub the eye itself.
Use a clean, soft material and avoid dragging dried debris across the eye.
If your dog seems painful, keeps the eye tightly closed, or resists having the area touched, stop trying to clean it and get veterinary guidance.
Cleaning away discharge may make your dog more comfortable.
It does not treat the underlying cause.
Why You Shouldn't Ignore Persistent Eye Problems
Some mild irritation may improve.
The problem is that owners cannot reliably tell at home which red eye is minor and which one involves a damaged cornea, pressure problem, foreign object, or another potentially serious condition.
Eye pain also deserves attention on its own. Squinting, repeated blinking, pawing, and keeping the eye closed are ways dogs may communicate discomfort.
If those behaviors continue, your dog is telling you something.
Can Dog Eye Problems Be Prevented?
You cannot prevent every eye problem, but you can reduce some risks.
Regularly look at your dog's eyes so you know what normal looks like.
Pay attention to:
- New discharge
- Changes in color
- Persistent tearing
- Swelling
- Cloudiness
- Repeated rubbing
- Squinting
Keep facial hair groomed appropriately for dogs whose hair grows around the eyes, and be careful with shampoo and other products during bathing.
Dogs that push through brush, tall grass, or wooded areas may also benefit from a quick visual eye check afterward.
If your dog has a breed-related eye anatomy issue or a history of recurring eye trouble, talk with your veterinarian about how frequently the eyes should be monitored.
The Bottom Line
The phrase dog eye infection describes what many owners think they are seeing when an eye becomes red, watery, or full of discharge.
Sometimes infection really is the problem.
Sometimes it is not.
Corneal injuries, dry eye, allergies, foreign objects, eyelid abnormalities, and other conditions can produce overlapping symptoms. In some cases, infection develops secondarily because another eye problem occurred first.
That makes the correct diagnosis more important than finding the quickest bottle of eye drops.
Watch for redness, discharge, swelling, and tearing—but pay especially close attention to pain, squinting, cloudiness, injury, and changes in vision.
When you are unsure, call your veterinarian.
Your dog's eyes are one place where catching the real problem early matters.
Frequently Asked Questions
What does a dog eye infection look like?
Possible signs include redness, discharge, swelling, excessive tearing, frequent blinking, squinting, and pawing at the eye. However, these symptoms can also occur with noninfectious eye problems, so an examination may be needed to determine the cause.
Does green discharge mean my dog has an eye infection?
Yellow or green discharge can occur when bacteria and inflammatory cells are involved, but discharge color alone cannot diagnose the underlying condition. Dry eye, corneal injury, and other problems can contribute to similar discharge or secondary infection.
Can a dog eye infection go away on its own?
Because owners cannot reliably distinguish a simple irritation from a corneal ulcer, dry eye, foreign body, or another potentially serious eye disorder at home, persistent symptoms should be discussed with a veterinarian rather than simply waiting for them to resolve.
Can I use human eye drops on my dog?
Do not use human eye medication unless your veterinarian specifically tells you to do so. Treatment depends on the underlying eye condition, and an inappropriate medication could delay correct treatment or make some problems worse.
Why is my dog squinting one eye?
Squinting can be a sign of eye pain. Possible causes include irritation, foreign material, trauma, and corneal disease. Persistent or pronounced squinting warrants prompt veterinary attention.
Are Bulldogs more prone to eye problems?
Some brachycephalic dogs, including Bulldogs and Pugs, can have facial and eyelid anatomy that leaves the cornea more exposed or prevents the eyelids from completely protecting it. Individual risk varies, so recurring symptoms should be evaluated by a veterinarian.
Sources & Further Reading
This article is provided for educational and informational purposes only and is not a substitute for examination, diagnosis, or treatment by a licensed veterinarian. If your dog is showing signs of eye pain, injury, sudden vision changes, or rapidly worsening symptoms, seek veterinary care.
Bhutan’s rabies milestone brings vaccine benefits and safety into focus. We examine documented reactions, ingredient research, and questions dog owners should ask.