Eye discharge is seen often in cats and is a symptom of an underlying problem not a disease in itself. There are a number of possible causes of eye discharge, it may be chronic or acute affect one eye or both.
Eye discharge may be clear and watery or thick and purulent. The type of discharge, along with accompanying symptoms can give your veterinarian a good indication as to the cause. For example, a thick, yellow discharge is a typical sign of bacterial infection.
Foreign bodies in any part of the eye can cause a number of problems (listed below) including conjunctivitis, corneal ulcers, dacryocystitis, and epiphora.
Blepharitis – Inflammation of the eyelid, this can be caused by bacterial infection, allergies, and congenital abnormalities.
Corneal ulcers – An open sore on the cornea, the clear tissue comprised of five layers at the front of the eye. Scratches, infection (viral, fungal or bacterial), injury, dry eye, structural abnormalities and foreign body can all result in corneal ulcers.
Blocked tear ducts (dacryocystitis) is an inflammation of the lacrimal sac, the upper, dilated end of the nasolacrimal duct which receives tears from the lacrimal ducts (tear drainage system). Brachycephalic breeds of cat such as Persians and Exotics are more prone to this condition. The most common cause is a foreign body such as plant awns becoming lodged in the nasolacrimal system leading to inflammation and possibly infection.
Feline upper respiratory infections (cat flu), usually caused by a virus (commonly herpes, calicivirus, feline reovirus), symptoms are similar to that of a cold or flu in humans with eye and nasal discharge, sneezing and fever.
Conjunctivitis(pinkeye)is an inflammation of the conjunctiva, the membrane which covers the front of the eyeball. There are several causes of conjunctivitis including infection, allergies, foreign object, injury and keratoconjunctivitis (dry eye).
Allergy can cause irritation and a watery discharge from the eyes. Common allergens include pollen, cigarette smoke, chemicals, dust and moulds (just to name a few).
Uveitis is inflammation of the iris, choroid or ciliary body in the eye it has many causes including infection (bacterial, viral, parasitic or fungal), diabetes, high blood pressure, tumours and idiopathic (no known cause).
Epiphora is an over production of tears, the most common cause is a blockage of the tear duct. Epiphora is usually associated with insufficient drainage, but can result in excessive production.
Trichiasis (rare in cats), eyelashes growing from the eyelid and rubbing against the cornea causing irritation, inflammation, and infection.
A stye is an infection of the sebaceous gland in the eyelid.
Dry eye (keratoconjunctivitis sicca or KCS/keratitis) is an inflammation of the cornea and conjunctiva due to a decrease in tear production, this can lead to minute abrasions on the eye due to the lack of lubrication, leading to corneal ulcers and/or inflammation and infection.
As you may have noticed, a lot of causes of eye discharge are due inflammation, infection, injury or allergies in the various parts of the eye.
Just like in people, a little eye discharge is normal, it can be slightly crusty or soft and is most often seen when your cat has woken up from a nap. This is known as rheum. This article relates to eye discharge that goes beyond that. As cat owners, we should have a general idea of what normal looks like. It is when we notice changes that we should look into what is happening. There are several types of eye discharge which can occur in cats.
Eye discharge may be yellow, green or clear. It may be thick, stringy or watery. It can be split into three types.
Serous (watery) clear discharge most commonly associated with viral infections, allergies, uveitis or irritants (cigarette smoke, chemicals etc)
Mucoid (stringy/roapy) clear, mucus discharge can be caused by allergy or dry eyes.
Mucopurulent is most often seen in bacterial infections. The discharge is thick and mucousy, it is usually yellow/green in colour and is typically caused by a bacterial infection.
Any abnormal eye discharge needs to be checked by a veterinarian, failure to do so could lead to blindness and/or loss of the eye if not treated.
Accompanying symptoms can help your vet narrow down the possible cause of the eye discharge. A cat with itchiness may have allergies, nasal discharge, and sneezing may indicate cat flu, if one eye is affected and your cat appears otherwise well, a corneal ulcer may be the culprit.
Your veterinarian will perform a complete physical examination of your cat including a close examination of the eye and observe other symptoms your cat may be experiencing (such as pain in the eye, nasal discharge etc). He will need to determine when the eye discharge began, does it occur at certain times of the day or year (seasonal), accompanying symptoms you may have observed.
Tests will depend on the suspected cause of the eye discharge and may include:
Biochemical profile, complete blood count, and urinalysis to check the overall health of your cat.
Fluorescein eye stain test– An orange dye (fluorescein) is placed in the eye which is then looked at with a UV light to look for corneal ulcers.
Blood pressure test if hypertension is suspected.
Schirmer tear test to measure tear production.
Culture of the discharge if a bacterial infection is suspected. This can identify the type of bacteria present, so the correct antibiotics can be prescribed.
Treatment of eye discharge depends on the cause but may include:
Topical antibiotics to treat bacterial infections.
Possible surgery to correct eyelid abnormalities with blepharitis.
Removal of any foreign body. This may be straightforward or surgery may be required if the body is lodged deeper within the eye or nasolacrimal duct.
Atropine is a medication which dilates the pupil and can be given to cats who have a corneal ulcer to relieve the pain of the pupil constantly dilating and constricting. As the pupil is constantly dilated on this medication, your cat will be more sensitive to light and should be given a darkened room to reduce discomfort.
Corticosteroid drops or ointment to reduce inflammation.
Medications to increase tear production, if this doesn’t work, artificial teardrops may be prescribed. These are necessary to provide moisture and lubrication to the eye.
Supportive care for upper respiratory infections. This may include oral antibiotics for bacterial infection, intravenous fluids to correct dehydration, encouraging your cat to eat and drink as a sick cat (particularly one who has cat flu) may be reluctant to eat and drink.
Antiviral drugs if your cat has a viral infection such as feline herpes.
Apply warm soaks to soften eye discharge, and gently wipe away with a clean gauze pad. Dispose of used dressings.
While your cat is recovering, he may need to wear an Elizabethan collar to avoid pawing at/irritating the eye(s).