By Dr Duncan Houston
Sticky discharge is not always a simple eye infection. When an eye does not have a healthy tear film, it becomes irritated and vulnerable to corneal damage, even if cleaning briefly makes it look better.
Dry eye often needs ongoing treatment. The aim is a comfortable, protected eye, with repeat measurements to check whether the plan is working.
Quick Answer
Dry eye, or keratoconjunctivitis sicca, causes inflammation because the surface of the eye is inadequately protected by tears. Signs include redness, thick mucus, squinting and a dull-looking cornea. Dogs commonly have reduced watery tear production; feline eye disease needs a species-specific assessment. Sudden pain, cloudiness or vision change needs urgent examination.
Why tears are more than water
The tear film lubricates the cornea, helps clear debris and supports its protective surface. When its watery component is reduced, mucus can become thick and stringy. Longstanding inflammation may leave pigment, scarring or ulcers, so removing discharge alone does not address the cause.
Immune-mediated damage to tear-producing glands is an important cause in dogs. Certain medicines, nerve damage and developmental problems can also contribute. Preserve the third eyelid gland whenever appropriate during treatment of a prolapsed gland; gland removal can increase the risk of later dry eye.
How urgent are the signs?
| Signs | Concern | Action |
|---|---|---|
| Recurring sticky discharge without obvious pain | Chronic surface disease is possible | Book an eye examination soon |
| Redness, rubbing or squinting | Pain or an ulcer may be present | Seek same-day assessment |
| Marked cloudiness, severe pain or sudden vision loss | Potentially sight-threatening disease | Contact an emergency clinic immediately |
How do vets diagnose dry eye?
A Schirmer tear test measures watery tear production using a small paper strip. The result is interpreted with the eye examination, medicines and clinical signs. Fluorescein staining checks for an ulcer, and other tests may assess eye pressure or tear-film quality.
Conjunctivitis, eyelid abnormalities, foreign material and corneal ulcers can produce overlapping signs. In cats, feline herpesvirus and other causes of surface disease need particular consideration. A canine tear-test threshold should not be used alone to diagnose every red feline eye.
What treatment involves
Veterinary guidance on canine dry eye describes treatment that protects the surface and, where appropriate, stimulates tear production. Prescribed ciclosporin or tacrolimus may help suitable cases, alongside lubricants. Antibiotics are used when indicated, not as a substitute for restoring surface protection.
Some dogs need lifelong treatment. Response is judged over follow-up examinations rather than a single good-looking day. Selected nerve-related cases need a different approach, and difficult cases may benefit from an ophthalmologist. Surgery to redirect a salivary duct is an option for some refractory cases, with its own complications.
When is this an emergency?
Seek urgent help if the eye is held shut, becomes suddenly cloudy, develops a visible defect or seems to lose vision. Do not restart old steroid drops without an examination: steroids can worsen an ulcer. New severe pain during treatment is not something to wait out until the routine recheck.
A workable daily care plan
- Keep a written schedule for each eye and each medicine.
- Clean discharge gently from surrounding skin using the method your vet recommends.
- Avoid touching the dropper tip to the eye, lashes or fingers.
- Ask how to space different preparations and which to apply last.
- Attend tear-test rechecks and report difficulty giving medication rather than silently missing doses.
Common mistakes
- Calling every episode a recurring infection without tear testing.
- Stopping medicines as soon as discharge improves.
- Assuming established corneal scarring will always reverse.
- Using redness-relief human drops or unapproved remedies.
Reducing further damage
Most immune-mediated cases cannot be prevented through diet. Consistent treatment, early investigation of eye changes and sensible protection from rubbing give the best chance of maintaining comfort and useful vision.
Frequently Asked Questions
Can dry eye cause blindness?
Yes. Severe ulcers, scarring and pigmentation can affect sight, which is why ongoing care matters.
Will lubricants cure it?
They help protect the surface but may not treat the underlying loss of tear production.
Can cats get dry eye?
Yes, but it is less commonly diagnosed than in dogs and requires careful assessment of the underlying cause.
Can I reduce the medication when the eye looks normal?
Only after your vet reviews the eye and tear results. Appearance alone can be misleading.
Dry eye is manageable for many animals, but consistency matters. Treat the surface, investigate the cause and respond promptly when comfort changes.
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