Q:My 5-year-old calico cat is in excellent health except for a continuing watering eye. The vet has treated her with neomycin and Polymyxin B Sulfates drops, but there is no lasting improvement. Someone told me this is a genetic condition and cannot be treated. Does that mean her conjunctivitis is permanent?

A: Teary, watery eyes are a common problem in feline medicine. The condition is typically the result of three culprits: feline herpesvirus-1 (fhv-1), feline chlamydia and feline mycoplasma. What you are describing sounds like the herpes virus, which is very prevalent in cats. The virus typically causes an initial infection in cats that includes runny eyes and nasal congestion that resolves within a few weeks. However, the virus is never truly eradicated and just becomes latent, often returning during periods of stress. The feline herpes virus is not infectious to humans, but it is transmissible to other cats.

Typically, if the symptoms are mild and there is just clear tearing, no treatment is needed; the virus will run its course and the symptoms should resolve on their own. However, if the infection worsens to the point where there is colored discharge or the eye is very swollen and reddened, this could indicate that a secondary bacterial infection has taken hold and that would require treatment with an antibiotic ointment, like the one your vet has prescribed.

Sometimes, if an infection has been very severe or a cat was repeatedly symptomatic, the duct that drains tears can become scarred and inflamed, and this will also cause a permanent overflow of tears. This is something that can be diagnosed by your veterinarian.

Christi Camblor, DVM, is the shelter medical director for the Sonoma Humane Society, and is also founder of the international animal welfare organization Compassion Without Borders.