Conjunctivitis (Pink Eye)

Conjunctivitis is inflammation of the conjunctiva — the thin pink membrane that lines the inside of the eyelids and covers the white of the eye. It is the single most common eye condition seen in cats, and while many cases are mild and self-limiting, it is uncomfortable and some causes can threaten vision if left untreated.

Unlike in dogs, the overwhelming majority of feline conjunctivitis is infectious. Feline herpesvirus type 1 (FHV-1) is the most frequent culprit. Like all herpesviruses it never fully leaves the body — once infected, a cat carries the virus for life, and it reactivates during stress, producing recurrent bouts of weepy, sore eyes. Chlamydia felis is another major cause, typically producing a more persistent, often one-sided infection that responds well to a specific course of antibiotics.

Because the signs of the different causes overlap, your vet may take swabs to identify the organism, and will examine the surface of the eye with a fluorescent stain to rule out a corneal ulcer — a more serious complication that can develop alongside herpesvirus infection. Treatment is directed at the cause: topical or oral antibiotics for bacterial and chlamydial cases, supportive care and sometimes antiviral medication for herpesvirus, and removal of any irritant in non-infectious cases.

At home, the most useful thing an owner can do is keep the eye clean. Gently wipe away discharge with a separate piece of damp cotton wool for each eye, working from the inner corner outward, to avoid spreading infection. Most uncomplicated cases improve within one to two weeks with appropriate treatment, though herpesvirus carriers may have flare-ups throughout life, usually triggered by stress.