At a glance
Eye discharge is an excessive amount of discharge from the eye, which can be crusty, mucousy or watery. It is always a sign of an underlying issue and can affect one eye or both eyes.
Treatment: The goal of treatment is to find and treat the underlying cause.
Eye discharge is a common symptom in cats, it is not a disease in itself but a symptom of an underlying disease. There are several 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.
When is eye discharge normal?
A little sleep in the corner of the eyes is normal, as you can see in the image below. What differentiates normal sleep from eye discharge? Several factors; the volume of normal sleep is small; it is usually somewhat dry and crusty, there are no additional symptoms such as soreness, inflammation, sneezing, or watery eyes.
Normal sleep in a cat’s eyes
Types of eye discharge
A small amount of eye discharge is normal; it can be slightly crusty or soft and is most often present 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. Several types of eye discharge can occur in cats.
Eye discharge may be yellow, green or clear and may be thick, stringy or watery.
- 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 usually due to bacterial infections. Discharge is thick and mucousy; it is usually yellow/green in colour.
Foreign body: Grass seeds, dust, sand and other debris can irritate the eye resulting in conjunctivitis, ulcers and dacryocystitis (infection of the lacrimal sac, secondary to obstruction).
Causes: A foreign body will usually result in eye discharge from one eye only (unilateral).
Treatment: Removal of the foreign body which may be flushed out with a saline solution or surgical removal of objects embedded in the eye.
Cat flu: One of the most common causes of eye discharge in cats is cat flu, an upper respiratory infection caused by several viruses and bacteria, which is similar to a cold in people. Kittens are most at risk due to their immature immune system.
Symptoms: In addition to eye discharge, the cat will display other symptoms such as fever, loss of appetite, sneezing and nasal discharge.
Treatment: Most cases of flu are viral, which require supportive care while the cat’s immune system mounts a response. This can include antiviral eye drops, fluid and nutritional support, as well as keeping the nose and eyes clear of discharge. In some cases, antibiotics may be prescribed to prevent or treat a secondary bacterial infection that can develop.
Blepharitis: Inflammation of the eyelid margins and surrounding skin and in some cases, the Meibomian glands, which are tiny glands on the eyelid margin which secrete an oily substance to keep tears within the eye. The condition can be chronic (long-standing) or acute (sudden onset), can affect one eye (unilateral) or both (bilateral), posterior (affecting the inner edge of the eyelid where it meets the eyeball), or anterior (affecting the front edge of the eyelid).
Causes: Blepharitis is typically secondary to an underlying eye disease. Causes include allergy, parasites, infection, eyelid abnormalities, tumours, trauma, inflammation and idiopathic (unknown).
Treatment: The goal of treatment is to address the underlying cause, where possible, this can include avoidance of the allergy, antibiotics, antiviral drops, surgery to correct abnormalities, and use a warm compress several times a day to remove discharge.
Corneal ulcers: A corneal ulcer is an open sore of the cornea, which is the transparent dome-shaped layer covering the front of the eye, including the iris, pupil, and anterior chamber. The outer layer of the cornea can be damaged due to scratches, particularly in younger cats, this is known as a corneal abrasion. Cells quickly repair this damage.
Causes: Erosion of the cornea, typically involving more than one layer is known as a corneal ulcer or ulcerative keratitis. It can occur as a result of injury or trauma (such as rubbing an itchy eye), infection (such as fungal infection, herpes or calicivirus), chemicals, damage due to structural abnormalities such as entropion, dry eye (lack of tear production) and foreign body. Secondary bacterial infection can occur once the cornea has become damaged, further complicating the problem.
Treatment: Find and treat the underlying cause where possible.
- Atropine, a medication that causes the pupil to dilate (enlarge) can offer relief as spasms of the ciliary muscle (which controls the dilation and constriction of the pupil) cause pain in the already damaged cornea. The constantly dilated pupil will be more sensitive to light, and your cat should be provided with a dark room to reduce discomfort.
- Antibiotics to treat bacterial infection.
- Supportive care for viral infections while the cat’s immune system mounts a response.
- Severe corneal ulcers will necessitate the eye be protected while the ulcer heals which usually involves suturing the eyelid shut for several days.
Blocked tear ducts (dacryocystitis): 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.
Causes: 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.
Treatment: Flush the tear duct if debris has caused a blockage, removal of any foreign bodies in the eye, antibiotics for bacterial infections and in some cases, surgery for cats with abnormal tear ducts.
Conjunctivitis (pinkeye): Conjunctivitis is a common disease in cats characterised by inflammation and pinkness of the conjunctiva, the pink membrane which covers the front of the eyeball and the inside of the eyelids. It can affect one eye (unilateral) or both eyes (bilateral) and covers a broad range of possible conditions. Conjunctival inflammation can be acute or chronic, infectious or non-infectious.
Causes: Infection, allergies, foreign object, irritants, injury, entropion, tumours and keratitis.
Treatment: The goal of treatment is to find and address the underlying cause. Mild cases of conjunctivitis may only require flushing of the eye with a saline solution.
- Purulent conjunctivitis requires eye irrigations, and warm saline soaks to loosen crusted eyelids.
- Antibiotic eye ointment (usually topical tetracyclines) applied several times a day to treat bacterial infections.
- Systemic antibiotics if your cat has Chlamydophila.
- Antiviral eye medications.
- Antibiotics to treat secondary bacterial infections which can develop in cats with viral conjunctivitis.
- L-Lysine to suppress viral replication of the herpes virus.
- Other treatments for cats with chronic FHV-1 conjunctivitis may include topical or systemic interferon and systemic anti-virals such as aciclovir.
- Removal of the allergen where possible and anti-inflammatories to treat allergies.
- If a foreign object is the cause, removal should solve the problem. This usually involves irrigating the eye with a saline solution to dislodge the object.
- Artificial tears to keep eyes moist for cats with dry eye.
- Cyclosporine is an immune-modulating medication that can help suppress immune system inflammation of the tear glands.
- Entropion may require corrective surgery.
Allergy: Allergies can cause irritation and a watery discharge from the eyes. Common allergens include pollen, cigarette smoke, chemicals, dust and moulds (to name a few). The frequency of symptoms can give a clue as to the cause, for example, symptoms that only develop at certain times of the year are often due to pollens. Itchy and inflamed skin are also common symptoms associated with allergies.
Treatment: Avoid the allergen where possible. It may be necessary to perform a skin patch test to determine the allergen. Common triggers include food, fleas, dust mites and pollens.
Uveitis: Inflammation of the uvea, the pigmented layer that lies between the inner retina and the outer fibrous layer composed of the sclera and cornea. It is one of the most common eye disorders in cats and can be potentially very serious.
Causes: Infection (bacterial, viral, parasitic or fungal), immune-mediated, cancer, diabetes and high blood pressure.
- Anti-inflammatory therapy. Corticosteroids may also be administered systemically, subconjunctivally (under the conjunctiva) and topically.
- Topical atropine ointment if necessary to keep the pupils dilated which relieves pain and stops the inflamed iris from sticking to the pupil, which causes further damage to the eye.
- Antibiotics to treat bacterial and protozoal infections.
- Diabetes should be brought under control; this usually involves a change in diet and/or insulin injections.
- Viral infections are usually managed with a combination of anti-viral medications (where available) and supportive care while your cat fights the disease.
- Eye removal (enucleation) to treat eye tumours.
- Steroids to treat immune-mediated disorders.
Overflow of tears, due to overproduction of tears or insufficient drainage.
Irritants, infection, abnormal eyelashes, abnormal tear ducts (common in brachycephalic breeds such as Persians and Exotics) and plastic dishes.
Find and treat the underlying cause, which may include avoid irritants such as chemicals and smoke inside the house, remove abnormal eyelashes, switch to ceramic or stainless steel food and water bowls, antibiotics for infection. Wipe away discharge with clean gauze and saline.
Trichiasis: An eyelid abnormality in which the eyelashes are misdirected and grow inwards toward the eye.
Causes: Eyelashes growing from the eyelid and rubbing against the cornea, causing irritation, inflammation, and infection.
Treatment: Removal of the eyelashes and eye ointments (antibiotics/lubricants) to coat the hairs with oil which protects the cornea from trauma.
Stye: An acute infection of the secretory glands of the eyelids due to a blockage.
Treatment: The veterinarian may recommend a warm compress to try and clear the blockage. Surgery to unblock the stye as well as antibiotics.
Dry eye (keratoconjunctivitis sicca or KCS/keratitis): 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.
- Cyclosporine is an immune-modulating medication that can suppress immune system inflammation of the tear glands. Administer twice a day. Long-term use is safe, and there are no residual side effects, however, stinging in the eye may occur. It can take several weeks for the effects of cyclosporine to take effect.
- Artificial tears three times a day to keep the eye moist and lubricated. These are the same products people use and are available over the counter from all pharmacies.
- Antibiotics to treat secondary bacterial infections.
- Topical corticosteroids may be necessary to treat eye inflammation.
- Cats who don’t respond to treatment may require parotid (salivary) duct transposition surgery. This involves moving the parotid duct, which is located on either side of the cheeks up towards the eyes so they can act as additional tear ducts. Saliva and tears are very similar in composition. While this surgery is usually successful, eye drops may still be required.
The most obvious symptom would be a discharge from one or both eyes. Other symptoms will vary depending on the underlying cause and may include the following:
- Itching which may be seasonal or non-seasonal
- Blinking more than usual
- Heavy, thick discharge may form a crust which leads to your cat’s eye(s) becoming stuck shut
- Nasal discharge
- Red/bloodshot eyes
- Meaty type appearance of the eyelids
- Prominent third eyelid, this is usually white but may be pink-tinged if there is a problem with the eye(s)
- Pain in the eyes and surrounding areas
- Change in the appearance of the eye, clouding, swelling, bulging
- Sensitivity to light (photophobia)
A veterinarian should always check abnormal eye discharge, failure to do so can lead to blindness and/or loss of the eye if not treated.
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, if one or both eyes are affected). 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 veterinarian’s index of suspicion, but may include:
- Baseline tests: 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.
- Schirmer tear test: This test measures tear production. A commercial filter strip is placed under the lower eyelid for 60 seconds. The moisture from the eye will slowly descend the strip and the level of moisture measured in mm.
- Culture and sensitivity: A sample of the discharge grown on a medium to assess bacteria present, to determine the best type of antibiotic to give.