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
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.
The retina is a thin, delicate membrane that lines the back of
the eye and is actually an extension of the optic nerve. In a healthy cat, the
retina receives light, processes it, and passes it on to the brain. If the
cells are damaged, it can’t send anything on. In a cat with retinal disease,
the retinal cells are damaged and the eye is no longer able to properly
transmit information regarding the light it receives. The visual image may be
blurred, and part or all of the visual field may be...
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
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.