Does Watery Eye Discharge Signal a Respiratory Infection?


I recently received the following question on cat health from a visitor to my website:

My cat has a slight watery discharge from her right eye and it sometimes “catches” dirt as it slides down her nose. I was just wondering if she has an upper respiratory infection and if so, what can I do about it. She doesn’t seem to have any other problems at present. Occasionally, I wipe her eye with a warm washcloth.

This is the first time I’ve seen this in her. I did take her out to get the paper a few times and it was cold so maybe she got something then.



An upper respiratory infection, or URI, is extremely common for a cat.

There are dozens of known bacteria and viruses that cause URIs. There probably are hundreds of yet-to-be-discovered causative agents as well. The most common virus that causes URIs is the feline rhinotracheitis virus, also known as the feline herpes virus (it is not sexually transmitted). A Chlamydia bacteria (also not sexually transmitted) is a common bacterial cause of URIs.

Very mild URIs cause watery eye discharge and nothing more. The eyes are the most frequently affected parts of the body, even though the condition is called a respiratory infection. As URIs become more severe, symptoms may include squinting, green or yellow eye discharge, sneezing, nasal discharge (ranging from mild clear discharge to more serious green or yellow discharge), coughing, poor appetite, and, most seriously, difficulty breathing.

Although URIs are contagious, many cats with no history of exposure to other cats may get them. Some of the agents, such as rhinotracheitis, cause lifelong infections that flare up sporadically. Often cats suffer URIs after suffering stress that weakens their immune systems. However, many cats seem to get infections for no ascertainable reason. Anita, I rather doubt that a couple of quick sojourns to get the paper are the cause of your cat’s symptoms.

The most common URI-causing pathogens can be detected using DNA testing. However, these tests usually aren’t necessary except in severe, refractory, or recurrent cases.

The overwhelming majority of URIs are self-limiting. In other words, most cats clear the infections in a week or two if they are provided a clean, stable, comfortable environment — and some extra love. I generally do not recommend treatment for URIs in cats who seem comfortable and are eating well. However, cats that lose their appetites, have trouble breathing, seem lethargic, squint significantly, have red eyes, cough excessively, or have green or yellow discharge from the eyes or nose may require treatment.

The treatments for URIs are limited. Antibiotics may treat bacterial infections (primary or secondary). Topical eye medications are sometimes employed to treat uncomfortable, swollen, or red eyes. Oral supplementation with L-lysine is purported to help prevent feline rhinotracheitis. More powerful antiviral medications also are available for oral rhinotracheitis. Nebulization with warm humid air can help to loosen respiratory secretions and clear blocked sinuses. There is no treatment for many of the viruses (known and unknown) that cause URIs.

Before embarking on treatment for a URI, be sure to ask your vet about the risks and benefits of the treatment. L-lysine and nebulization are very safe. However, antibiotics can cause side effects such as diarrhea or vomiting. And, some of the most commonly prescribed topical eye medications have been linked (though rarely) to life-threatening anaphylactic reactions. I prefer not to medicate cats with URIs unless absolutely necessary.

Some cats who suffer severe URIs may experience lingering or even lifelong mild clear discharge from one or both eyes. Anita, it sounds like this is not the case in your cat, since you imply that she only developed her symptoms recently. Therefore, it is more likely that your cat has a very mild URI. However, the distinction is irrelevant because her symptoms do not sound serious enough to warrant treatment. As long as things don’t get worse, I do not recommend taking any action other than periodically cleaning and drying her face.

A note about the discharge “catching dirt.” It probably isn’t actually dirt. Tears contain dark soluble components, which sometimes solidify as the tear dries and thickens. Either way, it’s not likely something to worry about.

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