Don't Diagnose on Your Own
Many of the cats brought to vets for red eyes and other ocular symptoms are exhibiting some form of conjunctivitis, which is characterized by inflammation of the mucous membrane that covers the inside of the eyelid and parts of the eye (the conjunctiva). There can be many causes of conjunctivitis, including bacterial infections, viral infections, and trauma.
Holt warns that the causes behind these infections may not necessarily be one-offs, as some turn out to be chronic problems. “One of the most common infectious organisms behind conjunctivitis is feline herpes virus, which is recurring,” she says. “So you might have to treat the eye many times over the course of several months or even years. Herpes virus is actually a big player in ocular surface disease in cats, too.” Trauma is also a possibility. If your cat’s eye gets scratched by a branch or she gets clawed by another cat, the damaged eye can then become infected and requires treatment. Trauma and some types of infections (e.g. feline herpes virus) may also lead to ulcers, an erosion of tissue off the surface of the eye.
Another reason pet owners shouldn’t try to diagnose their cat’s eye infections without professional assistance is because the drainage, redness, and squinting might not necessarily be caused by an infection. “Some cats develop dry eye disease as they get older. And there are different types of cancers that can develop in the eye,” Jones says. “This is why it’s so important that you know what the structures of your cat’s eyes look like, so if there is a change, you will know.