Dry Eye (Keratoconjunctivitis Sicca) in Dogs and Cats
By Dr Duncan Houston, DVM – Revised November 06, 2024 (VIN).
💧 Why Tears Are Essential
Tears lubricate, cleanse, and protect the eye. They contain antibacterial proteins and remove waste from the avascular cornea and conjunctiva.
Under normal conditions, tears are ~95% water; without sufficient moisture, eyes redden, corneas brown, and thick yellow discharge accumulates—leading to potential blindness.
🔍 What Is KCS?
Keratoconjunctivitis sicca (KCS) means inflammation (“-itis”) of the cornea and conjunctiva due to dryness (“sicca”). It stems from reduced aqueous tear production.
🧠 Causes of Dry Eye
- Canine distemper or feline herpesvirus.
- Congenital gland deficits (e.g., Yorkies).
- Medication side effects (e.g., sulfa antibiotics).
- Trauma, surgery (e.g. cherry eye gland removal), or head injuries.
- Immune-mediated gland destruction—common in Cocker Spaniels, Schnauzers, Westies.
👁️ Diagnosing KCS
The Schirmer Tear Test measures tear volume via a paper strip under the eyelid:
- ≥ 15 mm = normal
- 11–14 mm = borderline
- ≤ 10 mm = dry; ≤ 5 mm = severely dry
💊 Treatment Options
🐾 Topical Cyclosporine
0.2% cyclosporine ointment suppresses immune-mediated gland damage, often restoring tear production. Initial dosing is once–three times daily; response may take up to 4 months. Dogs with extremely low tear production still have ~80% chance of improvement.
🧪 Alternative Medications
- Tacrolimus: compounded alternative for cyclosporine non-responders.
- Pilocarpine: oral for neurogenic KCS (one-sided nerve issues), dose titrated to tolerable side effects.
🧴 Supportive Therapies
Artificial tears, gels, and ointments soothe and supplement natural tears, especially early on or if primary treatments fail. Use may range from 2–12 times daily.
Topical antibiotics prevent infection; steroids may reduce inflammation but are controversial when ulcer risk exists.
⚕️ Surgical Duct Transposition
For severe KCS unresponsive to meds, salivary gland transposition diverts saliva to lubricate the eye. Risks include corneal mineral deposits and excessive watering during meals.
📅 Monitoring & Prognosis
Recheck Schirmer tests in 3–4 weeks post-treatment. Adjust dosing based on response. Lifelong therapy is usually required.
✅ Key Takeaways
- KCS causes discomfort, red eyes, discharge, and vision loss.
- Diagnose with Schirmer Tear Test.
- Cyclosporine ointment is the frontline treatment.
- Alternatives include tacrolimus, pilocarpine, lubricants, and surgery.
- Lifelong follow-up ensures optimal eye health and comfort.
© 2025 — Dr Duncan Houston, BVSc
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