Is Conjunctivitis in Cats Contagious?

If Kitty has conjunctivitis, it means the conjunctiva in her eye is inflamed. The conjunctiva is the mucous membrane that covers her eyeball and lines her eyelids, including her third eyelid. When all's well with Kitty's eyes, the conjunctiva isn't readily visible and is a pale, pink color. When the membrane becomes inflamed, it's often red and swollen and causes a discharge from her eye. The discharge can be clear and watery, or thick and yellow, or greenish in color. Fluid buildup in the eye and squinting are also common symptoms. Occasionally, an environmental factor such as irritating dust causes conjunctivitis, but usually a virus or bacteria are to blame.

Viral conjunctivitis is one of the contagious forms of the illness, and it's usually caused by herpesvirus or calicivirus. The discharge from Kitty's eyes, mouth or nose can easily infect other cats who share her litter box and food and water dishes. If she grooms another cat or sneezes, she can pass along the virus. Since both viruses are highly contagious, it's common to see it in animal shelters, catteries and homes with more than one cat. Some cats become latent carriers of the herpesvirus, meaning they can share it without showing their own symptoms. If both of Kitty's eyes are showing signs of conjunctivitis, it's probably being caused by a virus.

If only one of Kitty's eyes is showing symptoms, her conjunctivitis was probably brought on by bacteria, such as chlamydophila or mycoplasma. Like the herpesvirus and calicivirus, these bacteria are highly contagious and spread the same way as are viral infections. Sneezing, sharing water and food dishes, and using the same litter box all promote the spread of the bacteria. The chlamydophila bacteria don't survive long in their environment, which may explain why this form of conjunctivitis occurs in about 30 percent of the cases. As with the viral forms, it's normal for bacterial conjunctivitis to break in multiple cat homes, catteries and animal shelters because it's easily shared.

Younger cats tend to develop conjunctivitis more frequently than older cats. If Kitty has conjunctivitis, she should be isolated if she shares her home with other cats so she doesn't infect her housemates. You can help prevent the spread of conjunctivitis by practicing good hygiene: Thoroughly wash your hands before and after interacting with any infected cats, as you can act as a carrier. If Kitty has viral conjunctivitis, she may carry it with her the rest of her life. Stress or illness may cause it to flare up. Good nutrition, vaccinations and keeping Kitty healthy and stress-free go a long way to keep conjunctivitis from revisiting her.