Why is my cat tearing up or have watery eyes?

Watery eyes can come from irritants, eye disease, odor irritation, allergies, or respiratory infection. First check for debris like fur or sand and flush with saline or pet eye wash, then apply drops to prevent infection. If the eye is red or inflamed, it may be conjunctivitis or keratitis from bacterial or viral infection – see a vet for diagnosis. Respiratory infection, odors, or allergies also cause tearing; watch for sneezing, runny nose, or red conjunctiva, and remove any allergens or strong smells at home.