TL;DR: Clear, watery eye discharge in cats is usually a low-urgency response to mild irritants or allergies; however, you should seek veterinary care if the discharge changes color or the eye appears painful.
What causes clear, watery discharge in my cat's eye?
Clear, watery discharge from a cat's eye, medically known as epiphora, is a common symptom where the eye produces excess tears or the tear ducts fail to drain properly. Unlike thick or colored discharge, clear tearing is usually a response to a mild irritant, such as dust, pollen, or a slight breeze. It can also be caused by minor allergies or a mild flare-up of a common feline respiratory virus.
Is clear eye discharge in my cat a medical emergency?
The urgency level for clear, watery tearing is currently Low. If your cat is otherwise acting normally and eating well, this is generally not an immediate emergency. You should monitor the eye for changes over the next 24 hours and contact a veterinarian if:
- The eye is held shut or the cat is squinting.
- The discharge becomes thick, yellow, or green.
- The eye itself looks cloudy or red.
How does providing a photo help triage my cat's eye condition?
Providing a high-quality, close-up photo of your cat's eye is one of the most helpful things you can do for a triage assistant. A clear image allows us to:
- Look for subtle signs of inflammation.
- Check if the third eyelid is raised.
- Identify any foreign bodies trapped in the eye.
- Maintain a visual record to compare against if the condition changes later in the day.
Clinical Context (Merck Veterinary Manual)
In cats presenting with watery eyes, triage should focus on identifying the presence of serous ocular discharge, conjunctival hyperemia, and chemosis, which may indicate conjunctivitis. Unilateral or bilateral involvement should be noted, as well as the presence of follicles on the inside of the third eyelid in more severe cases. While keratitis is rare, its presence may suggest co-infection with other organisms such as feline herpesvirus 1. Cytologic examination of Giemsa-stained conjunctival scrapings can aid in identifying chlamydiae and mycoplasmas. Samples of ocular, nasal, or caudal pharyngeal secretions for PCR may help establish a definitive diagnosis and identify the causative agent.
Chapter: Infectious Disease, Ophthalmology
Source: The Merck Veterinary Manual, 11th Edition (Page 1482)