Common Eye Problems

Conjunctivitis – Dogs

What?  Conjunctivitis is a medical term for infection or inflammation of the eye, similar to Pink Eye in people.  In dogs, this is usually due to contagious bacteria that dogs can get from each other.

Symptoms:  The eyes will usually get red, squinty and often produce a green-yellow mucous discharge.  Although both eyes are usually affected, owners may notice only one eye affected initially before it spreads to the other.

Diagnosis:  Usually a physical exam is enough but if there is any doubt, a quick test to make sure that the cornea is not physically damaged or scratched is easy to do.  This test is called a fluorescein stain and it is a dye that sticks to deeper layers of the cornea that have been exposed from trauma or ulceration.

Treatment:  An ointment or drop that contains antibiotics and anti-inflammatories is usually prescribed.  It is also important to avoid contact with other dogs until the infection is gone!

Conjunctivitis – Cats

What?  Unlike dogs, cats typically get eye infections from viruses.  Herpesvirus is usually the most common cause of conjunctivitis although other viruses and bacteria can play a role as well.  Because herpesvirus is a common upper respiratory virus, eye infections in cats can also be associated with sneezing and nasal discharge.

Symptoms:  The eyes will usually get red, squinty and swollen.  The eye discharge can vary from clear to brown to yellow-green mucous.  As mentioned above, other symptoms like sneezing, fever and decreased appetite can also be present if the infection turns into a full-blown upper respiratory infection.

Diagnosis:  Usually a physical exam is enough but because long-standing chronic infections can lead to physical ulceration of the cornea, a fluorescein stain may often be recommended.

Treatment:  Viruses usually need to run their course and depend upon the cat’s immune system to fight them off.  Eye ointments with antibiotics and sometimes anti-inflammatories are usually prescribed regardless to treat a possible rarer mycobacterial infection and to prevent secondary bacterial infections.  For cats with more chronic or recurrent upper respiratory infections or conjunctivitis, a product called Viralys can be used daily or at times of stress to help prevent virus replication.

Corneal ulceration

What?  Corneal ulcerations are defects in the superficial layers of the eye, similar to scrapes or scratches on your skin.  Ulcerations can be caused by trauma (cat claws, thorns, bushes, sticks) or due to more chronic processes like herpesvirus conjunctivitis in cats which erode the protective superficial layers of the eye.

Symptoms:  Symptoms can resemble a simple conjunctivitis with clear or coloured discharge, a red eye, squinting and pawing at the eye because of pain.  Unlike conjunctivitis though, only one eye is typically affected.

Diagnosis:  Sometimes a physical exam is enough to detect a physical defect on the surface of the cornea.  A fluorescein stain is still essential to determine how deep and how big the ulcer is.

Treatment:  Ulcers may be treated differently based on the cause of the ulcer.  Treatment may also be adjusted based on how deep and how large the ulcer is.  Uncomplicated superficial ulcers are treated with 1) antibiotics to prevent secondary infections  from eroding the cornea further 2) Pain control topically on the surface of the eye, by mouth or both 3) The dreaded head collar/cone of shame to prevent pawing or rubbing the eye which can rub off any healing that has occurred.  Treatment is continued until the ulcer has completely healed which is confirmed by follow-up fluorescein stains at the vet’s office.

Cherry Eye

What?  Cherry eye describes the fleshy part of the third eyelid that peeks out from the corner of the eye when it gets swollen and inflamed.  It is actually the gland of the third eyelid that is physically swollen.  There is some genetic predisposition to developing Cherry Eye and some of the breeds most commonly affected include English Bulldogs, Cocker Spaniels, Beagles and Shih Tzu’s.

Symptoms:  Owners will usually notice a swollen red mass poking out at the corner of one or both eyes.  Sometimes the eye will also look a little more irritated or watery than usual.

Diagnosis:  A physical exam is usually enough to confirm the diagnosis.

Treatment:  Although attempts to shrink the third eyelid mass with eye drops can be occasionally or temporarily successful, it is usually not a permanent fix.  Surgery is the most consistent way of replacing the swollen gland back into its permanent pocket.  Eye drops and head collars are needed temporarily until healing from surgery is complete.


What?  Glaucoma happens when the pressure inside the eye is too high.  This can be caused by a number of different hereditary, anatomical and inflammatory factors inside the eye.  Ultimately, a lack of drainage of the fluid inside the eye causes increased pressure and pain.

Symptoms:  In only rare cases does the eye look physically bigger.  Instead, the eye is usually bloodshot and painful.  Dogs and cats will often squint or rub their eyes when they are sore.  Sometimes blindness can be an early symptom as well.

Diagnosis:  Because glaucoma is very painful and can lead to poor outcomes if left untreated, it is important to get a quick diagnosis.  Tonometry is a way to measure the pressures inside the eye.  The eye is usually frozen with an eye drop so that a tonometer can be used to touch the surface of the cornea.

Treatment:  If caught early enough, glaucoma can be treated with drops that aim at reducing the pressure inside the eye.  If an eye doesn’t recover well or is permanently blind, sometimes removing the eye surgically is the best solution.


What?  Uveitis is inflammation of the structures inside the eye causing pain and discomfort.  Anything that causes infection or inflammation in the rest of the body can also cause inflammation inside the eye (Viruses, parasites, bacteria, autoimmune diseases, cancers).

Symptoms:  Most dogs and cats will show signs of pain:  squinting, blinking or rubbing their eye with their paws.  Redness of the eye and small pupils are usually common symptoms as well.  If the problem isn’t just localized to the eye, pets may look sick in other ways as well as seen by changes in appetite and personality.

Diagnosis:  A full eye exam and pressure testing (as for glaucoma) are the first steps in identifying uveitis.  Because uveitis can be caused by a number of local and generalized disorders, examining the whole pet is important.  Bloodwork, xrays or ultrasound may also be recommended depending on findings during the physical exam.

Treatment:  Treatment really needs to be geared toward the underlying cause.  This can vary depending on the diagnosis.  Eye drops or oral medications to control pain and inflammation in the affected eye(s) are often used until the underlying problem is resolved.