Canine Dry Eye (KCS): Causes, Symptoms, and Treatment

Canine dry eye is a chronic inflammatory condition affecting the cornea and conjunctiva caused by lack of tear production. The medical term is keratoconjunctivitis sicca or KCS. 

The primary cause of dry eye in dogs is autoimmune disease. Other causes include breed predispositions, old age, congenital abnormalities, medication side effects, injuries, neurological issues, systemic conditions, and environmental factors. 

Excessive blinking, eye redness, eye discharge, corneal cloudiness, ulcers, and eye pawing are telltale signs of dog dry eye. 

Keratoconjunctivitis sicca is diagnosed with the Schirmer Tear Test. The test measures the tear production, which is typically between 15 and 25 mm per minute. Values below 15 confirm the diagnosis of KCS in dogs. 

The treatment for dry eyes includes lacrimostimulants, lacrimomimetics, antibiotics, and surgery. Natural remedies for keratoconjunctivitis sicca dog are coconut oil applied directly to the dry eye and CBD and fish oil given orally. 

What is Dry Eye in Dogs?

Dry eye in dogs is a condition in which the dog’s cornea and conjunctiva dehydrate. The medical term for dry eye is keratoconjunctivitis sicca or KCS, which refers to dryness inflammation.  

Dry eye is “a common canine eye disease, with reported annual incidences of 0.3%–1.52% in North America,” according to a study “Immune-Mediated Keratoconjunctivitis Sicca in Dogs: Current Perspectives on Management” published in Veterinary Medicine in 2015. 

Keratoconjunctivitis sicca develops secondary to decreased tear production (quantitative dry eye) or reduced tear quality (qualitative dry eye).

Dry eye is a multifactorial and complex issue causing discomfort. Prompt veterinary attention is necessary for KCS dogs to prevent complications and permanent damage. 

What Does Tear Production Contribute to Dry Eye in Dogs?

Tear production contributes to dry eye in dogs by altering the quality or quantity of the tear film. 

The tear film is a three-layered film that protects, lubricates, and nurtures the eyes. The three distinct layers are mucus (inner layer), water (middle layer), and oil (outer layer). 

The mucus is produced by the conjunctival goblet cells, the lacrimal glands' water, and the meibomian glands' oil. 

Dogs with KCS lack the water or aqueous part of the tear film due to decreased activity of the lacrimal apparatus. 

The dog’s eye has two lacrimal glands, including one lacrimal gland (LG) above the outer corner of the eye and one nictitans gland or third eyelid gland (TELG) located at the base of the third eyelid. 

What is the Difference Between Dry Eyes and Keratoconjunctivitis Sicca (KCS) in Dogs?

The difference between dry eyes and keratoconjunctivitis sicca is terminology. Dry eyes are known by many names, including dry eye disease, dry eye syndrome, keratoconjunctivitis sicca, and keratitis sicca. 

The term keratoconjunctivitis sicca translates to dry inflammation of the cornea and conjunctiva. 

Keratoconjunctivitis sicca is the long and mouthful dry eye medical term. The acronym KCS is used to make a diagnosis.  

What Causes Dry Eye in Dogs?

The causes of dry eye in dogs are listed below. 

• Autoimmune Diseases: KCS “is associated with underlying immunologic disorders in 40% of cases,” and “autoantibodies in lacrimal, salivary, or pancreatic glands are the most common culprits,” according to a study “Keratoconjunctivitis Sicca: Immunological Evaluation of 62 Canine Cases” issued in Veterinary Medicine: Research and Reports in 1985.
• Congenital Abnormalities: Congenital alacrimia is an inherited dry eye syndrome. The congenital abnormality affects one eye and is widespread among Yorkshire Terrier breed members.  
• Breed Predispositions: Dry eye has a breed predisposition and is more common in Cocker Spaniels, Cavalier King Charles Spaniels, English Bulldogs, Pugs, Lhasa Apsos, Shih Tzus, Westies, Pekingese, Boxers, and Boston Terriers. Brachycephalic breeds are more prone to KCS because tears easily evaporate from their large, protruding eyes. 
• Aging: “KCS most commonly affects middle-aged to older dogs,” explains a report on “Keratoconjunctivitis Sicca (KCS) or Dry Eye in Dogs” by VCA Hospitals. 
• Eyelid Issues: Eyelid issues such as entropion (inward inversion), ectropion (outward inversion), and eyelid lumps (chalazion or tumors), in some cases, unable proper eyelid closure causing dry eyes. 
• Medication Side Effects: Certain medications cause dry eye, with the dryness being a temporary or permanent side effect. An example of such a med is the antibiotic class of sulfa drugs. 
• Neurological Disorders: Damage of the nerves responsible for lacrimal gland function causes dry eye in dogs. The most common cause of nerve damage is untreated inner ear infection. Dogs with neurogenic dry eyes have a dry nose in many cases. 
• Previous Eye Injuries or Surgeries: Keratoconjunctivitis sicca results from eye injuries and surgeries that damage the tear production system. A dog dry eye caused by surgical errors during operation (most commonly the cherry eye surgery) is called iatrogenic keratoconjunctivitis sicca. 
• Underlying Health Conditions: Underlying hormonal imbalances, such as hypothyroidism, Cushing’s disease, diabetes, and infectious diseases like leishmaniasis and canine distemper, cause dry eyes in some cases. 
• Environmental Factors: Air temperature and relative humidity are believed to play an important role in the growth of keratoconjunctivitis sicca in dogs. 
• Environmental Pollutants: Airborne allergens, cigarette smoke, automobile emission gas, and aerosolized cleaning products contribute to KCS development in predisposed dogs. 

What are the Symptoms of KCS in Dogs?

The symptoms of KCS in dogs are listed below. 

• Excessive Blinking: Excessive blinking is marked by rapid eyelid movements and helps distribute tears along the eye's surface. 
• Eye Redness: Redness is a telltale sign of inflammation, and red eyes are common in dogs with keratoconjunctivitis sicca. 
• Discharge from Eyes: The reduced aqueous portion of the tears increases the oil and mucus concentration in the tear film, resulting in a thick discharge.  
• Corneal Cloudiness: Corneal cloudiness appears as a milky layer over the eye and is a sign of advanced damage to the cornea. 
• Corneal Ulcers: Corneal ulcers are deep cornea defects and are a widespread complication of keratoconjunctivitis sicca in dogs. 
• Pawing: Dogs with KCS paw at their eyes to soothe the discomfort and get relief. 
• Eyelid Lump: Eyelid lumps are more common on the upper eyelids and impair the dog’s ability to close the eye.  
• Watery Eyes: Water loss in the tear film stimulates the eye to produce low-quality tears, which make the eyes look watery. 
• Decreased Tear Production: Decreased tear production is the hallmark of KCS in dogs. 

1. Excessive Blinking

Excessive blinking is rapid eyelid movement. KCS dogs blink excessively to distribute moisture throughout the eye surface and ease discomfort. 

Blinking resolves once the underlying cause is managed. Keep the eyes wet with artificial tears to reduce blinking. Coconut oil is an excellent alternative to tears for keratoconjunctivitis sicca dog conditions.  

2. Eye Redness

Redness is one of the signature inflammation signs. Chronic inflammation is at the base of KCS, resulting in red eyes. 

Treating the cause of KCS resolves the redness. Supplements like CBD oil and fish oil reduce red eyes in dogs. CBD and fish oil help because of their anti-inflammatory properties. 

3. Discharge from Eyes

Eye discharge is a collection of mucus, oil, and debris. Discharge accumulates at the corners of the eyes. The discharge in KCS dogs is thick because they lack the watery part of the tear film. 

Resolving the underlying KCS cause manages the discharge. Clean the eye discharge in dogs with a warm and damp washcloth to provide temporary relief. 

4. Corneal Cloudiness

Corneal cloudiness is a loss of the cornea’s normal transparency. Cloudiness manifests as a milky curtain over the eye. Cloudiness impairs vision. 

Immediate veterinary care is warranted for cloudy eyes in dogs. Loss of corneal transparency is a sign of advanced damage to the eye's surface. 

5. Corneal Ulcers

Corneal ulcers are open sores in the cornea. The damage starts as an erosion, which is more superficial, but progresses to an ulcer. Ulcers are deep deficits of the corneal surface. 

Seek immediate veterinary attention if dealing with ulcers. Corneal ulcers in dogs lead to blindness if left untreated. 

6. Pawing

Eye pawing is when the dog directs its paws towards the eyes. Dogs paw in an attempt to soothe the irritation. KCS in dogs is not itchy but uncomfortable. 

Pawing provides much-needed relief. Consider putting an Elizabethan collar on the dog if the pawing is excessive and causing further eye damage. 

7. Eyelid Lump 

An eyelid lump is a growth on the dog’s eyelid. Lumps are more common on the upper eyelid. Chalazion, a non-tumorous growth, is the most frequently seen eyelid lump. 

Large chalazia, in some cases, prevents the eyelid from closing. The treatment includes topical and oral medication. A cancerous eyelid lump in dogs requires surgical removal. 

8. Watery Eyes

Watery eyes have a glassy appearance. Dogs with KCS lack the watery portion of the tear film. The body supports the production of low-quality tears to compensate for the lack of moisture.

The treatment entails managing the underlying cause of keratoconjunctivitis sicca. Daily cleaning is helpful because watery eyes in dogs are prone to forming crusts. 

9. Decreased tear production

Decreased tear production is the main dog dry eye sign. The lack of tears is not immediately visible. Secondary changes due to dryness in the later stages indicate low tear production. 

Topical or systemic medications are used to treat decreased tear production. Artificial tears and virgin coconut oil applied directly to the eye help increase moisture and lubrication. 

How to Diagnose Dry Eye in Dogs?

The instructions on how to diagnose dry eye in dogs are listed below. 

1. Schedule a Clinical Examination. Consult the veterinarian for an examination. The clinical examination is the cornerstone of every diagnostic process. The vet identifies physical changes that help create a preliminary diagnosis. 
2. Administer a Schirmer Tear Test. Perform a Schirmer Tear Test, which is the gold standard for diagnosing KCS and entails placing a scaled filter paper inside the lower eyelid. The paper measures how many tears are produced. The normal production in dogs is between 15-25 mm/min.  
3. Apply Fluorescein Staining. Use Fluorescein staining to determine the presence of ulcers as a dry eye complication. The veterinarian drops the fluorescent stain on the eye, turning green if there is an ulcer. 
4. Use Tear Film Break-Up Time (TBUT). Measure tear film break-up time to see how fast tears evaporate from the eye's surface. TBUT is defined as the time lapse between the last blink and the emergence of a dry spot on the cornea. The normal TBUT in dogs is over 20 seconds. 
5. Observe Ocular Surface Staining. Apply lissamine green staining (LGS) to the ocular surface to detect changes on the dog’s eye surface associated with excessive dryness and lack of proper tear flow. 
6. Assess the Dog’s Tear Quality. Evaluate tear quality through various tests, such as measuring tear meniscus, evaporation rate, osmolarity, corneal topography, interferometry, and aberrometry. 
7. Evaluate Associated Conditions. Allow the vet to perform a thorough eye examination to determine the presence of co-existing eye problems. The assessment includes reflexes and tonometry. 

What is the Treatment for Dry Eye in Dogs?

The treatment for dry eye in dogs is lacrimostimulants, lacrimomimetics, antibiotics, or surgery, depending on the underlying cause. 

Lacrimostimulants are medications that promote tear production. The two most commonly used options are ophthalmic cyclosporine and tacrolimus. Cyclosporine and tacrolimus suppress the dog’s immune system, preventing it from attacking the lacrimal apparatus.  

Lacrimomimetics are artificial tears designed to hydrate the eye surface and help flush the eye from dirt, debris, and allergens. Artificial tears are not a standalone treatment and must be combined with other approaches. 

Antibiotics are recommended for dogs with advanced dry eyes with complications like corneal ulcers and bacterial infections. Keratoconjunctivitis sicca triggers several eye problems in dogs that require tailored management. 

Surgery is reserved for dogs that fail to respond to treatment. The surgery for dry eye in dogs is called parotid duct transposition (PDT) and entails relocating the dog’s saliva gland to the eye. 

“PDT is a successful procedure based on clinical findings and in terms of owner perception,” according to a study “Parotid duct transposition in dogs: a retrospective review of 92 eyes from 1999 to 2009,” published in Veterinary Ophthalmology in 2012.

Starting dry eye treatment upon diagnosis is vital. KCS in dogs is progressive and impairs vision if left untreated. 

How can Dry Eyes in Dogs be Managed?

Dry eyes in dogs can be managed by treating the underlying cause and lubricating the eye. Certain causes of KCS are treatable with medications, and others require surgical correction. 

Managing dry eyes starts by determining the underlying cause and creating a treatment plan. Using tear stimulants and tear replacements helps keep the eye moist. 

Increase tear production with lacrostimulants (tear stimulants). Commonly used options include cyclosporine and tacrolimus. The meds are applied to the eye once or twice daily but are not universally effective for dogs with dry eyes. 

Use artificial tears if the dog does not respond well to tear stimulants. Artificial tears made for dogs come as drops or ointments. 

Talk to the veterinarian and discuss the best management plan for the dog’s dry eyes. The vet considers factors like age, lifestyle, and overall health to provide the best advice. 

Are there Natural Remedies for Dry Eye in Dogs?

Yes, there are natural remedies for dry eyes in dogs. Natural remedies do not provide a definitive treatment but help relieve the symptoms. 

The best natural remedy for dry eyes is coconut oil, which has anti-inflammatory, antiseptic, antibacterial, and moisturizing properties. 

Virgin coconut oil or VCO “Is safe to be used as ocular rewetting agent,” reports a study, “A Pilot Study: The Efficacy of Virgin Coconut Oil as Ocular Rewetting Agent on Rabbit Eyes,” published in eCAM in 2015. 

The study found that virgin coconut oil reduced eye dryness as effectively as commercial eye drops without causing damage or side effects to the rabbits’ eyes. 

How can the Owner Provide Home Care for Dogs with Dry Eyes?

Pet owners can provide home care for dogs with dry eyes by cleaning the eyes and supporting general eye health. 

Clean the dogs’ eyes several times daily using a wet and warm washcloth. Cleaning removes the crusty discharge, moistens the eye surface, and allows the eye drops to penetrate. 

Supplement the dog with pet CBD oil and omega-rich fish oil to support eye health. CBD and fish oil have potent anti-inflammatory properties, which help alleviate dry eye symptoms. 

What Happens if Dog Dry Eyes are Left Untreated?

If dog dry eyes are left untreated, permanent eye damage occurs. Keratoconjunctivitis sicca is a chronic and progressive condition. 

KCS causes painful ulcers if left untreated. The ulcers are prone to rupturing, which is followed by excessive corneal scarring. The ulcers, combined with scar tissue formation, result in permanent blindness in dogs in severe cases.

Can CBD Oil Help Dry Eyes?

Yes, CBD oil can help dry eyes. CBD oil for dogs modulates the immune system and has potent anti-inflammatory properties. 

Immune modulation is important because an overactive immune system is the most common cause of dry eyes. Anti-inflammatory medications help decrease eye irritation.  

The immune-modulating and anti-inflammatory properties of CBD for dogs are shown in a study, “Effect of Cannabidiol (CBD) on Canine Inflammatory Response: An Ex Vivo Study on LPS Stimulated Whole Blood,” published in Veterinary Sciences in 2021.

The recommended CBD dose for dogs is between 1 and 5 milligrams per 10 pounds. The ideal  CBD oil dosage and safety for dogs with dry eyes is 3 mg per 10 pounds.