Healthy Cats

Conjunctivitis (Pinkeye) in Cats - Types, Symptoms, Causes and Treatments

Conjunctivitis is an inflammation of the membrane covering the back of the eyelids and surface of the eyeball up to the cornea. It is one of the most common eye problems in cats. Conjunctivitis in cats almost always has an underlying infectious cause. The most common cause is the herpesvirus (FHV-1), and the second most common is chlamydophila. Signs are a red eye, discharge, and pawing at the eye to relieve itching. The conjunctival tissues may be red and swollen. Untreated conjunctivitis may progress to vision-threatening problems.

Conjunctivitis is not painful-although it is itchy. If the eye is red, irritated, and painful to touch, consider the possibility of keratitis, uveitis, or glaucoma. Delay in treating these conditions could result in loss of vision.

Serous Conjunctivitis

This is a mild condition in which the membrane looks pink and somewhat swollen. The discharge is clear and watery and is caused by physical irritants such as wind, cold weather, dust, or various allergens. This condition must be distinguished from a tearing problem.

Serous conjunctivitis may be the first sign of a feline viral respiratory disease or a chlamydophila infection. Eye worms are a rare cause of conjunctivitis.

Treatment: Mild, irritating forms of conjunctivitis can be treated at home. The eye should be cleansed with a dilute solution of boric acid for ophthalmic use, artificial tears, or a sterile ophthalmic irrigating solution that can be purchased over the counter and used as directed for people. You should see definite improvement within 24 hours. If not, bring your cat to the veterinarian.

Purulent Conjunctivitis

Purulent conjunctivitis begins as serous conjunctivitis that becomes purulent. Thick secretions crust the eyelids. The eye discharge contains mucus or pus. This suggests secondary bacterial infection.

When the discharge involves both eyes simultaneously, suspect a virus. This could be herpesvirus or calicivirus. When it involves one eye at first and progresses to the other eye several days later, suspect chlamydophila or mycoplasma. These microorganisms can be detected under a microscope by your veterinarian, in scrapings taken from the conjunctival membrane. Ulcers on the cornea are diagnostic for herpesvirus conjunctivitis.

Conjunctivitis due to fungal infection is rare and requires special laboratory aid for diagnosis.

Treatment: Purulent conjunctivitis requires eye irrigations and sometimes warm soaks to loosen crusted eyelids. Antibiotics are applied to the eye surface several times a day. They should be continued for seven days beyond apparent cure. An ointment containing a combination of neomycin, bacitracin, and polymyxin (such as Neosporin ophthalmic ointment) often works well.

If the condition is caused by chlamydophila or mycoplasma, eyedrops containing tetracycline or chloramphenicol are the antibiotics of choice. Chlamydophila conjunctivitis can result from cats shedding organisms in their stool or urine after the infection appears to be cleared. This carrier state can be treated by your veterinarian with a three-week course of doxycycline or a week of azithromycin.