As pet owners, we’re often quick to notice if our dog or cat is limping, not eating, or acting out of the ordinary—but changes in their eyes can be subtle and easy to overlook. One such eye condition is keratoconjunctivitis sicca (KCS), commonly known as dry eye disease. While it may sound like a complicated term, KCS is a manageable condition if caught early. Left untreated, however, it can cause your pet discomfort, pain, and even permanent eye damage.
This blog aims to break down what KCS is, how it affects your pet, what symptoms to watch for, and how it can be treated.
What is Keratoconjunctivitis Sicca (KCS)?
Keratoconjunctivitis sicca (KCS) is a condition where the eyes don’t produce enough natural tears. Tears are essential because they keep the surface of the eye—known as the cornea—moist, clean, and protected. Without enough tears, the eye becomes dry, inflamed, and vulnerable to infection or injury.
The condition is particularly common in dogs, though it can also occur in cats and other animals. In simple terms, KCS is like having chronically dry eyes. Imagine getting sand in your eye and not being able to blink it away. That’s close to what pets with KCS feel every day if the condition isn’t managed.
Why Are Tears So Important?
Tears aren’t just salty water. They’re made up of three layers—oil, water, and mucus—which work together to form a thin film over the eye. This film:
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Keeps the eye’s surface smooth and clear
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Washes away dust and debris
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Protects against bacteria and infections
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Provides oxygen and nutrients to the cornea
When tear production is reduced, the eye loses its first line of defense. This leads to discomfort and can eventually cause corneal ulcers, scarring, and even vision loss.
What Causes KCS in Pets?
There are several potential causes of dry eye in animals:
1. Immune-Mediated Destruction
In most dogs, KCS happens because the immune system mistakenly attacks the tear-producing glands, damaging them and reducing tear production over time. This is called immune-mediated KCS and is the most common form.
2. Breed Predisposition
Some breeds are more prone to developing KCS. These include:
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Cocker Spaniels
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Bulldogs
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West Highland White Terriers
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Lhasa Apsos
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Shih Tzus
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Pugs
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Miniature Schnauzers
These breeds are genetically predisposed, so if you own one of them, it’s especially important to stay alert to symptoms.
3. Medications
Some drugs, like sulfa-based antibiotics or certain anaesthetics, can reduce tear production temporarily—or even permanently.
4. Viral Infections
In cats, feline herpesvirus can affect the tear glands and cause KCS.
5. Surgical Complications
In rare cases, surgery (like the removal of the third eyelid gland, also known as the cherry eye gland) can contribute to KCS.
6. Neurological Issues
Nerve damage that affects the ability of the eye to blink or stimulate tear production may also lead to KCS.
Symptoms of KCS: What to Look For
Dry eye in pets can be mistaken for conjunctivitis (eye infection), allergies, or just general irritation. That’s why it’s crucial to know the signs:
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Red or bloodshot eyes
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Thick, yellow or green discharge
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Squinting or excessive blinking
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Eye rubbing or pawing at the face
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A dull or cloudy-looking cornea
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Dry, sticky appearance of the eye surface
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Recurring eye infections or ulcers
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Vision changes or bumping into objects
If your pet’s eye looks uncomfortable or “not quite right,” it’s always best to let your vet take a look.
How Is KCS Diagnosed?
Diagnosing KCS is relatively simple. Your vet will likely perform a Schirmer Tear Test, which involves placing a small paper strip under your pet’s eyelid to measure tear production over a minute. If the tears produced are below normal, KCS is diagnosed.
Additional tests may be used to check for corneal damage or secondary infections.
Can KCS Be Treated?
The good news is KCS is treatable, especially when caught early. However, it is a lifelong condition, meaning your pet will need ongoing care.
1. Medication
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Cyclosporine or Tacrolimus: These are prescription eye drops that help stimulate tear production by calming the immune system’s attack on the tear glands.
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Artificial Tears: These lubricate the eyes to provide temporary relief, especially during flare-ups.
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Antibiotics: If there’s a secondary infection, your vet may prescribe topical antibiotics.
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Steroids: Sometimes used to reduce inflammation, but with caution.
2. Surgery
In very severe or unresponsive cases, a parotid duct transposition may be considered. This procedure redirects a salivary gland duct to the eye, using saliva as a tear substitute. It’s a last resort, but can significantly improve comfort
What Happens If KCS Is Left Untreated?
Without treatment, KCS can lead to:
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Chronic pain and discomfort
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Frequent eye infections
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Corneal ulcers and scarring
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Permanent vision loss or blindness
Most importantly, untreated KCS can severely affect your pet’s quality of life. Just like humans, pets need their vision for navigation, interaction, and play.
Living with a Pet Who Has KCS
Caring for a pet with dry eye means committing to daily eye care—but it’s not as daunting as it sounds. Most pets quickly learn to tolerate their drops or ointment, especially when it’s paired with treats, cuddles, or playtime.
Here are a few tips to manage the condition:
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Stick to the medication schedule prescribed by your vet
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Keep the eye area clean and free of discharge
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Watch for changes in symptoms and follow up regularly
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Never use human eye drops unless instructed—some can be harmful to animals
With the right care, most pets with KCS go on to live happy, pain-free lives.
Final Thoughts: Know the Signs, Act Early
Keratoconjunctivitis sicca may be a tongue-twister, but its impact is no joke. As pet parents, staying informed and proactive makes all the difference. If your pet’s eyes seem irritated, sticky, or constantly red, don’t brush it off—early intervention can save your pet from chronic pain and potential blindness.
When in doubt, schedule a visit to your vet. Their eyes are in your hands.