The Classic Comprehensive Handbook of Cat Care
What to Do When Your Cat Is Sick: CONJUNCTIVITIS
Conjunctivitis is an inflammation, sometimes caused by or accompanied by infection of the membranes (conjunctiva) that line the lids and cover part of the eye. It is probably the most common eye problem of cats because it occurs in association with several of the common respiratory infections and also because the conjunctiva is exposed to trauma and many irritants. Conjunctivitis may affect one eye alone or both simultaneously. The first sign of conjunctivitis may only be an increase in tearing with no other signs of irritation or illness. In many instances this type of conjunctival irritation will clear spontaneously in three to seven days. In other cases, the tearing changes or the first sign you notice is an excessive amount of sticky yellowish discharge that accumulates at the medial corners of the eye. Conjunctivitis accompanied by this kind of discharge is often associated with bacterial infection.
There are many degrees of inflammation. In mild cases the conjunctiva itself may look only slightly swollen or wrinkled. In more severe cases the conjunctiva is more pink than normal, sometimes very swollen, and the vessels of the sclera are very prominent. Although mild conjunctivitis may clear without treatment, cases that are persistent, cause inflammation of the lids and/or discomfort, or are accompanied by other signs of illness must be treated by a veterinarian to avoid permanent damage to the eye.
In mild cases, the first step in treatment at home is to examine your cat thoroughly for other signs of illness and to examine the eyes looking for a local cause of conjunctivitis to be removed if found. If there are no general signs of illness, if the eyes themselves look normal, and if the discharge is of the clear, watery type, you may choose to postpone treatment for a few days. Cats with mild conjunctivitis that persists beyond seventy-two hours or that includes a persistent sticky discharge, as well as those with conjunctivitis accompanied by other signs of illness should be examined by a veterinarian who can determine whether antibiotics are necessary or who may find causes not obvious to you.
Conjunctivitis occurs frequently in kittens less than six weeks old. For more information.
For another cause of conjunctivitis, see Eyeworms.