Dry Eye (KCS) in Pets: When Tears Stop Flowing
Dry eye syndrome leaves your pet's eyes irritated and vulnerable to infection. Daily medication can restore comfort and protect vision.
Keratoconjunctivitis sicca (KCS), commonly called dry eye, occurs when the tear glands don't produce enough tears to keep the eye lubricated. Without adequate tear film, the cornea becomes dry, irritated, and susceptible to infection and ulceration.
Key Points
- Dry eye is diagnosed when tear production measures less than 10 mm/minute
- Cocker Spaniels, Bulldogs, Westies, and Shih Tzus have genetic predisposition
- Common causes include immune-mediated disease, trauma, and certain medications
- Artificial tears and immunomodulating drops are the mainstays of treatment
- Untreated dry eye leads to chronic discomfort, corneal damage, and blindness
- Lifelong treatment is required; there is no cure for most cases
Understanding Tear Production
Tears have three layers: oil (from meibomian glands), water (from lacrimal and nictitans glands), and mucus (from conjunctival goblet cells). The watery middle layer is what's measured in dry eye. Without it, the cornea dehydrates, becomes cloudy, and develops pigmentary keratitis — brown-black discoloration. Mucus accumulates, creating thick, stringy discharge.
Signs of Dry Eye
The earliest sign is a thick, ropey discharge from one or both eyes. The eyes may appear dull or lack their normal shine. Pets blink frequently and may squint. The conjunctiva is red and irritated. In chronic cases, the cornea develops brown-black pigment that can obstruct vision. Some pets develop recurrent corneal ulcers. Vision may gradually decline.
Diagnosis
The Schirmer tear test (STT) is the gold standard — a paper strip placed in the lower eyelid measures tear production over 60 seconds. Normal is 15-25 mm; KCS is diagnosed below 10 mm. Fluorescein staining checks for ulcers. Rose bengal or lissamine green stains devitalized cells. Aqueous tear deficiency is distinguished from evaporative dry eye (meibomian gland dysfunction).
Managing Dry Eye
Cyclosporine eye drops (Optimmune, Restasis) suppress the immune attack on tear glands and often increase tear production. Tacrolimus is used when cyclosporine is insufficient. Artificial tears (carboxymethylcellulose, hyaluronic acid) supplement natural tears. Pilocarpine stimulates tear production in some cases. Parotid duct transposition surgery redirects saliva to the eye in severe, refractory cases.
When to See a Vet Immediately
- Your pet has thick, stringy eye discharge
- The eyes appear dull and lack their normal luster
- There's brown-black discoloration on the cornea
- Your pet blinks excessively or squints
- Recurrent eye infections or ulcers occur
How RVC Can Help
This article is for educational purposes only and does not replace professional veterinary advice. If your pet is showing any symptoms, please contact Royal Veterinary Center immediately at +853 6677 6611.