An old dog’s eyes may appear to bulge when one or both eyeballs seem more prominent than they normally do.
The change may be subtle, with the eye looking slightly larger or more forward, or it may be obvious enough that the eyelids no longer seem to fit normally around the eye.
A bulging eye is not usually something to dismiss as a normal part of aging. Several conditions can push the eyeball forward.
Some causes are painful and can threaten vision, so a new or worsening bulging eye should be evaluated by a veterinarian.
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Old Dog Eyes Bulging: What It Means
An old dog may have bulging or protruding eyes because of increased pressure behind the eye, inflammation, trauma, infection, bleeding, or a mass within the tissues surrounding the eye.
Glaucoma can also cause an eye to become enlarged and painful, while sudden displacement of the eyeball can occur following trauma.
A bulging eye is not a normal consequence of aging and should be evaluated immediately.
Sudden protrusion, severe eye pain, inability to close the eyelids, redness, cloudiness, vision changes, or an eye that appears to be pushed forward requires urgent veterinary care to protect the eye and determine the underlying cause.
Common Causes of Bulging Eyes in an Old Dog
Glaucoma
Glaucoma occurs when pressure inside the eye becomes abnormally high. Over time, prolonged increased pressure can enlarge the eyeball, while sudden severe glaucoma can cause significant pain, redness, vision loss, pupil changes, and a firm-feeling eye.
In an older dog, glaucoma is an important possibility when an eye appears larger than the other.
Early changes can be subtle, so dog owners may not notice that the eye is becoming enlarged until the condition has progressed.
A bulging or enlarged eye accompanied by redness, cloudiness, a dilated pupil, squinting, or obvious discomfort needs prompt veterinary attention.
Related: Old dog’s eyes moving back and forth (What it means)
Inflammation Behind the Eye
Inflammation of the tissues within the eye socket can push the eyeball forward. This is sometimes called orbital cellulitis.
Orbital inflammation can develop because of an infection, a foreign object, or infection spreading from nearby structures.
Dogs may have swelling around the eye, a visible third eyelid, conjunctival swelling, and significant pain, particularly when opening the mouth.
Because the swelling is located behind the eyeball, the eye can appear to suddenly bulge outward even though the eyeball itself has not become larger.
Tooth-Root or Dental Disease
Dental disease can sometimes affect the tissues surrounding the eye.
A tooth-root infection involving an upper tooth can extend into nearby tissues and contribute to inflammation behind the eye.
Dogs with this type of problem may show pain when opening the mouth, facial swelling, difficulty chewing, or a bulging eye.
This possibility is particularly important when bulging of the eye occurs along with signs of oral discomfort.
A Mass or Tumor Behind the Eye
A growth within the eye socket can gradually push the eyeball forward.
Orbital masses can resemble other causes of exophthalmos, but a slowly progressive bulging eye without the severe pain associated with some infections can be one clue that a structural problem needs investigation.
In an older dog, a newly developing mass is one of the reasons a persistent change in eye position should be examined rather than attributed to age.
Trauma
An injury to the face or eye can cause the eyeball to become displaced or protrude from its normal position.
Severe traumatic proptosis occurs when the eye is forced forward out of the orbit.
This is an emergency because the exposed eye can suffer serious damage, and the chances of preserving vision depend partly on the severity and duration of the injury.
Trauma can also cause swelling around the eye without completely displacing the eyeball.
Related: Old Dog’s Eyes (Common Senior Dog Eye Problems)
Lens Luxation and Secondary Glaucoma
A displaced lens can sometimes interfere with the normal drainage of fluid from the eye and lead to increased intraocular pressure.
Anterior lens luxation can cause glaucoma, which may then result in pain, vision loss, and enlargement or other changes in the eye.
This is another reason why an apparently enlarged eye should not be evaluated by appearance alone.
Severe Eye Inflammation
Inflammation inside the eye can cause redness, pain, cloudiness, changes in the pupil, and altered appearance of the eyeball.
Not every inflammatory eye condition causes true bulging, but significant swelling or secondary changes can make one eye look substantially different from the other.
A veterinary eye examination can determine whether the problem is primarily inside the eye or in the surrounding tissues.
Eyelid Problems Making the Eye Look More Prominent
Sometimes the eyeball itself is not enlarged or pushed forward. Changes to the eyelids can make the eye appear more exposed or prominent.
Eyelid disorders, inflammation, facial nerve problems, and other conditions can alter how the eyelids sit around the eye.
This distinction matters because treatment depends on whether the problem involves the eyeball, eyelids, or tissues behind the eye.
Related: Old Dog Eyes Droopy (Why it happens)
Old Dog’s One Eye Is Bulging
A single bulging eye is particularly important to have examined because several localized problems can affect only one side.
Possible causes include glaucoma, orbital inflammation, dental disease extending behind the eye, trauma, lens problems, or a mass within the orbit.
Pay attention to other differences between the two eyes, including redness, cloudiness, pupil size, discharge, squinting, a visible third eyelid, or changes in vision.
A sudden difference between the eyes is more concerning than an appearance that has been unchanged for a long time.
Old Dog’s Both Eyes Are Bulging
Bulging of both eyes can have different implications from a single enlarged or displaced eye.
Certain eye diseases can eventually affect both eyes, while systemic conditions can also produce changes involving both eyes. Glaucoma, for example, can occur in both eyes in dogs, particularly in breeds predisposed to the condition.
If both eyes appear progressively larger, a veterinarian should determine whether the eyeballs are truly enlarged or whether another change is making them appear more prominent.
Old Dog’s Eye Bulging but Not Red
An eye does not have to be obviously red to deserve evaluation.
Some conditions, particularly slowly developing structural problems, may produce a change in eye position without dramatic redness or discharge.
Orbital masses, for example, can cause forward displacement of the eye and may not produce the same pain pattern as an acute orbital infection.
A persistent bulging eye should therefore be assessed even when the dog seems comfortable.
Old Dog’s Eye Bulging and Squinting
Bulging accompanied by squinting is more concerning because squinting can indicate eye pain.
Glaucoma can cause severe pain, redness, pupil abnormalities, and vision loss, while inflammation around the eye can also cause discomfort.
A dog may not cry or otherwise make its pain obvious, so squinting, rubbing the face, reluctance to open the eye, or unusual behavior can be important clues.
Old Dog’s Eye Bulging and Third Eyelid Showing
A visible third eyelid can accompany conditions affecting the tissues around the eye.
With orbital inflammation, for example, swelling behind the eyeball can push the eye forward and cause the third eyelid to become more prominent.
If a bulging eye and prominent third eyelid develop suddenly, particularly with swelling or pain, veterinary assessment should not be delayed.
When to Call or Visit the Vet
A newly bulging or increasingly prominent eye in an older dog should be evaluated by a veterinarian.
Seek immediate veterinary attention if your dog has:
Sudden bulging or displacement of the eye
Severe squinting or obvious eye pain
Redness or swelling around the eye
A cloudy, blue, or discolored cornea
A dilated or unusually slow-moving pupil
Sudden vision changes or bumping into objects
A visible or swollen third eyelid
Difficulty opening the mouth or chewing
Facial swelling
Eye discharge, especially if thick or accompanied by swelling
Recent trauma to the head or eye
An eye that cannot close normally
Rapidly worsening bulging
Severe weakness, collapse, or other major illness signs
If the eye has been forced forward after an injury, this is an emergency. Traumatic eye prolapse requires immediate veterinary treatment.
Old Dog Eyes Bulging: Treatment
Treatment depends on whether the eye is enlarged because of glaucoma, pushed forward by inflammation or a mass, affected by trauma, or altered by another eye or eyelid disorder.
The veterinarian will examine the eye and surrounding tissues, assess vision and pupil responses, and may measure intraocular pressure with a tonometer when glaucoma is suspected.
Depending on the findings, additional eye testing, dental assessment, X-rays, ultrasound, CT, or other imaging may be needed to investigate the tissues behind the eye. Treatment is then directed at the underlying diagnosis.
Key Takeaway
An old dog’s eyes appearing to bulge can be caused by glaucoma, inflammation behind the eye, dental disease, trauma, a mass, lens problems, or other eye and orbital disorders.
Some causes can be painful and threaten vision, so a new change should not simply be considered part of getting older.
Pay attention to whether one or both eyes are affected and whether there is redness, cloudiness, squinting, a visible third eyelid, facial swelling, changes in the pupil, vision problems, or pain when opening the mouth.
If an older dog’s eye suddenly becomes bulging, displaced, painful, cloudy, or difficult to close, veterinary evaluation is important.
A rapidly protruding eye after trauma requires immediate veterinary attention because the eye can be seriously damaged.