A healthy eye depends on a thin, stable tear film that renews with every blink. When that protective tear film becomes inadequate, the eye’s surface can become irritated, inflamed, and vulnerable to injury. Animal Eye Care of New England provides specialty veterinary care for dry eye in dogs and cats in the Providence, RI area, with services including evaluation of tear production, corneal health, and conditions that interfere with normal lubrication.

Dry eye is often called keratoconjunctivitis sicca, or KCS. Keratoconjunctivitis sicca is much more common in dogs than in cats. Plus, the causes can differ between species. Recognizing the signs of dry eye in dogs, understanding low tear production in pets, and identifying corneal damage can help families seek treatment before chronic dryness threatens comfort or vision.

What Is Dry Eye?

Dry eye occurs when the tear film cannot adequately protect and lubricate the ocular surface. The most common form involves inadequate production of the watery (aqueous) portion of tears. Veterinarians often call this quantitative KCS.

The tear film helps maintain a smooth optical surface, supports the cornea, flushes away small particles, and contributes to the eye’s defenses against microorganisms. When tear quantity or quality is inadequate, the cornea and conjunctiva can become chronically inflamed.

Some pets can also have qualitative tear-film problems. In these cases, the watery portion of the tears may not be dramatically reduced, but another component of the tear film is abnormal, and the tears do not remain stable across the eye. 

Why Can a Dry Eye Produce Thick Discharge?

It may seem contradictory for an eye described as “dry” to have visible discharge. With inadequate watery tears, mucus is no longer diluted and cleared from the ocular surface as effectively. As a result, discharge can be thick, sticky, stringy, or mucopurulent rather than the clear, watery tearing many people associate with eye irritation.

Discharge may collect at the inner corner of the eye or coat the corneal surface and eyelids. It can be white, gray, yellow, or green, depending on the ocular surface condition and whether a secondary infection is present. Persistent discharge is one reason KCS is sometimes mistaken for simple conjunctivitis.

Cleaning away the mucus may temporarily improve the eye, but it does not correct inadequate tear production. When discharge keeps returning, especially with redness or discomfort, evaluate the underlying tear film. Treating only the visible mucus can allow chronic corneal damage to continue.

What Are the Signs of Dry Eye in Dogs?

Common signs include redness, thick ocular discharge, squinting, rubbing, and a dull or dry-looking corneal surface. Some dogs develop recurrent episodes that look like conjunctivitis. Others have chronic discharge that returns soon after cleaning the eye.

As the disease progresses, blood vessels can grow into the normally clear cornea. Scar tissue and dark pigment may also develop. When these changes become extensive, they can interfere with vision, and the altered ocular surface may be more susceptible to painful corneal ulcers.

Symptoms do not always look equally severe in both eyes. KCS is commonly bilateral, but one eye may produce fewer tears or show more advanced corneal changes. We must test and evaluate each eye separately rather than assuming both sides are affected equally.

What Causes Keratoconjunctivitis Sicca in Dogs?

Immune-mediated inflammation of the tear-producing glands is the most common cause of canine KCS. The immune system damages the tissue that produces the aqueous portion of tears, reducing the amount available to protect the eye. This form commonly requires long-term treatment to support tear production and control inflammation.

Other causes are possible. Certain medications, trauma, congenital abnormalities, infection, and neurological dysfunction can interfere with normal tearing. Some dogs develop dry eye after removal or loss of function of tear-producing tissue associated with the third eyelid.

Because different mechanisms can produce similar outward symptoms, determining the cause matters. A dog with typical bilateral immune-mediated disease may require a different management strategy from a dog with a neurological tear deficiency affecting one side. Medical history and the rest of the examination help make that distinction.

Some Dog Breeds Have Greater Risk

KCS can occur in any dog, but some breeds are more prone to it than others. Breeds with increased risk include American Cocker Spaniels, English Bulldogs, West Highland White Terriers, Shih Tzus, Pugs, Lhasa Apsos, and others. Genetics may contribute to susceptibility in certain dogs.

Brachycephalic dogs can face additional ocular-surface challenges because prominent eyes, incomplete blinking, or eyelid abnormalities may increase exposure. A dog can have both deficient tear production and anatomical factors that make the cornea harder to protect. Treatment should consider the entire ocular surface, not just the tear-test number.

Breed risk does not mean every dog of that breed will develop KCS. Likewise, a mixed-breed dog or a breed not commonly associated with dry eye can still be affected. Persistent symptoms should guide the decision to seek an examination.

What Is Neurogenic Dry Eye?

Normal tear production depends partly on nerve signals. When nerves controlling the lacrimal glands are disrupted, tear production can decrease even if the glandular tissue is still present. This form is called neurogenic KCS.

Neurogenic disease may affect one eye and can be accompanied by a dry nostril on the same side. That combination can provide an important diagnostic clue. Other neurological findings may or may not be present depending on where the nerve pathway is affected.

Treatment can differ from the more common immune-mediated form. This is another reason not to assume every dry eye should receive the same medication plan. A veterinarian or veterinary ophthalmologist can evaluate tear production, nasal moisture, neurological findings, and the rest of the eye before recommending therapy.

Can Cats Get Dry Eye?

Yes, but feline KCS is much less common than canine KCS. Dry eye in cats is associated with chronic feline herpesvirus infection and scarring of the conjunctiva and tear-duct openings. Other ocular diseases can also disrupt the feline tear film.

A cat may develop redness, discharge, squinting, corneal inflammation, or ulceration. These symptoms overlap with feline herpesvirus disease and several other common feline eye disorders, so contact your vet immediately if you spot these red flags.

How Is Dry Eye Diagnosed?

The Schirmer tear test is the standard test for measuring aqueous tear production. A small sterile paper strip is placed inside the lower eyelid for one minute, and tears wick along the strip. The amount of wetting is measured and interpreted with the patient’s species, symptoms, and ocular examination.

The test is generally performed before placing drops or other medications in the eye because those substances can affect results. We test both eyes, even when only one appears abnormal. Comparing the two sides can provide useful information.

A low measurement can support a diagnosis of quantitative KCS, but veterinarians do not interpret the number in isolation. The veterinarian also looks at the cornea, conjunctiva, eyelids, discharge, tear-film appearance, and medical history. This broader assessment helps identify complications and other problems occurring at the same time.

Why Is Fluorescein Staining Important?

Dryness can make the corneal surface more vulnerable to injury, so the veterinarian may apply fluorescein stain to check for an ulcer. The dye adheres to areas where the protective corneal epithelium has been disrupted. A positive stain helps determine whether an open corneal defect is present.

This information can affect treatment choices. Do not use certain anti-inflammatory eye medications when a corneal ulcer is present. Checking the corneal surface before selecting therapy helps guide appropriate treatment.

Fluorescein can also provide information about tear drainage in some circumstances. However, the primary reason for staining a painful or chronically dry eye is often to evaluate corneal integrity. Ulceration requires appropriate treatment, in addition to managing the underlying tear deficiency.

What Is Qualitative Dry Eye?

Tears are not simply water. The precorneal tear film includes lipid, aqueous, and mucin components that work together to create a stable protective layer. An abnormality in any of these components can destabilize the tear film even when the measured aqueous volume is not severely reduced. This is sometimes called qualitative KCS. 

A veterinary ophthalmologist may evaluate tear-film breakup time or use other stains to assess ocular-surface health. Treatment can include lubricating products chosen to improve tear-film stability, but the exact plan depends on the type of deficiency and other ocular findings.

How Is Dry Eye Treated?

Treatment has two broad goals: increase or support natural tear production when possible and provide lubrication to protect the ocular surface. Veterinarians commonly treat dogs with immune-mediated KCS with topical medications that reduce immune-mediated inflammation in the tear glands while stimulating tear production. Add lubricating drops, gels, or ointments based on the severity of dryness.

Treatment is individualized. A dog with a corneal ulcer, secondary infection, severe mucus accumulation, neurogenic disease, or another concurrent problem may require additional therapy. Cats with tear-film disease may also need treatment directed at the underlying feline ocular condition.

All medications must authorize and review all medications. Do not substitute human redness-relief products, leftover antibiotic drops, or another pet’s medication. The wrong product may not address the tear deficiency and may be inappropriate if corneal ulceration or another eye disease is present.

Dry Eye Treatment Often Requires Long-Term Care

Many dogs with immune-mediated KCS need ongoing, often lifelong, topical treatment. Tear-stimulating medications may not produce their full effect immediately, so early recheck exams help determine whether tear production is improving. Stopping therapy because the discharge disappears can allow dryness and inflammation to return.

Medication schedules may change as the eye responds. A veterinarian may repeat the Schirmer tear test, assess discharge, and examine the cornea for blood vessels, pigment, ulcers, or other changes. These findings provide a more complete picture than symptoms alone.

Consistency at home is important. If giving eye medication becomes difficult, ask the veterinary team for a demonstration or alternative handling strategies.

Can Lubricating Eye Drops Treat KCS by Themselves?

Artificial tears and other ocular lubricants can improve surface moisture and comfort, but they do not necessarily address the underlying cause of immune-mediated KCS. Dogs with functioning tear-gland tissue often benefit from prescription medications that stimulate natural tear production and reduce inflammation.

Lubrication can still be an important part of treatment, particularly when tear production is very low or while tear-stimulating medication is taking effect. Select the formulation and frequency for the individual patient. Drops, gels, and ointments behave differently on the ocular surface.

What Happens If Dry Eye Is Not Treated?

Chronic dryness continually irritates the cornea and conjunctiva. The eye can respond by developing inflammation, blood vessels, scar tissue, and pigment across the corneal surface. Over time, these changes can reduce transparency and vision.

Corneal ulcers are another important complication. Tears protect the ocular surface, and an inadequately lubricated cornea is more vulnerable to epithelial damage. An ulcer adds pain and can become a more serious threat if it deepens or becomes infected.

Untreated KCS can become more than a nuisance caused by discharge. Maintaining a comfortable, clear cornea is the long-term goal. Early diagnosis and consistent management can help reduce the chronic damage associated with inadequate tears.

Does Thick Yellow or Green Discharge Always Mean Infection?

No. Thick discharge is a classic feature of KCS because inadequate watery tears allow mucus and debris to accumulate. Yellow or green coloration can occur, and secondary infection is possible, but color alone does not determine the underlying diagnosis.

Antibiotic treatment by itself does not correct inadequate tear production. A dog may appear temporarily improved while the ocular surface remains chronically dry. If discharge returns repeatedly after treatment, consider tear production as part of the evaluation.

A veterinarian can examine the cornea, perform tear testing, and determine whether infection or ulceration is also present. This approach addresses the reason for the discharge instead of relying only on its appearance.

When Is Surgery Considered?

Most canine KCS is managed medically, but surgery can be considered in severe cases that do not respond adequately to appropriate medical therapy. One procedure is parotid duct transposition, which redirects a salivary duct so saliva moistens the ocular surface.

Saliva is not identical to natural tears, so this procedure has limitations and potential complications. Veterinarians generally reserve it for carefully selected patients rather than using it as first-line treatment for routine KCS. A veterinary ophthalmologist can determine whether a dog is a reasonable candidate.

Surgery does not replace diagnosis or medical management. First, we need to evaluate the underlying cause, the condition of the cornea, and the response to medication. Treatment decisions are based on long-term comfort and protection of the ocular surface.

When Does a Dry Eye Need Prompt Veterinary Care?

Seek prompt care if your pet suddenly begins holding an eye closed, develops marked cloudiness, has a visible corneal spot, experiences trauma, or shows a significant increase in redness or pain. These changes can indicate a corneal ulcer or another complication that requires examination.

Any sudden decline in vision deserves prompt attention. Chronic KCS can affect vision through pigmentation, scarring, and other corneal changes, but abrupt visual problems can have additional causes. 

Do not restart an old eye medication without veterinary guidance when symptoms suddenly worsen. An eye that was previously dry can develop a new ulcer, infection, glaucoma, or another condition. Current examination findings should guide treatment.

PetMD has an article on dry eye in dogs. The University of Illinois College of Veterinary Medicine also has a helpful piece on dry eye in dogs.

Frequently Asked Questions About Dry Eye in Pets

What does dry eye look like in a dog?

Dry eye commonly causes persistent redness and thick, sticky, or mucus-like discharge, not just a dry-looking surface. Dogs may also squint, rub their eyes, or develop corneal cloudiness. Chronic disease can cause blood vessel growth, scarring, and dark pigment across the normally transparent cornea.

These symptoms overlap with other eye disorders, including conjunctivitis and corneal ulcers. A Schirmer tear test measures aqueous tear production and helps determine whether KCS is contributing. Your veterinarian will likely examine the cornea for complications at the same visit.

Is dry eye painful for dogs and cats?

Yes, an inadequately lubricated ocular surface can be irritating and uncomfortable, and corneal ulcers associated with severe dryness can be painful. Pets may squint, rub the face, resist having the eye touched, or become quieter when the ocular surface is sore.

Visible discomfort does not always tell the tale. Chronic changes can develop gradually, allowing a pet to continue normal activities despite ongoing irritation. Persistent discharge, redness, or corneal changes warrant evaluation even when your animal companion doesn’t seem obviously painful.

Is dry eye more common in dogs or cats?

KCS is primarily a canine disease and occurs much less frequently in cats. In dogs, the most common form involves immune-mediated damage to the tear-producing glands. Feline cases have been associated with conditions such as chronic feline herpesvirus infection and conjunctival scarring.

Because the causes differ, chronic eye irritation in cats should not be treated as canine KCS. A feline ophthalmic exam should consider corneal disease, herpesvirus, eyelid abnormalities, and other problems.

Can dry eye cause blindness in a pet?

Yes. Severe or poorly controlled KCS can cause chronic corneal inflammation, blood-vessel growth, fibrosis, pigmentation, and ulceration. When scarring or pigment becomes extensive across the central cornea, it can block light and reduce vision. Serious ulcers can create additional threats to the eye.

Early diagnosis and consistent treatment can help protect corneal health and comfort. If your pet already has significant corneal changes, a veterinary ophthalmologist can evaluate remaining vision and determine which problems may improve with treatment.

Does a pet with dry eye need lifelong treatment?

Many dogs with immune-mediated KCS require lifelong topical therapy because the underlying tear-gland disease does not simply disappear when symptoms improve. Medication may stimulate tear production and control inflammation, while supplemental lubrication can support the ocular surface.

Recheck examinations help determine whether the treatment remains effective. Do not stop prescribed medication because the eye looks normal unless the veterinarian recommends a change. Improved appearance may mean that treatment is successfully controlling the disease rather than that KCS has resolved.

Contact a Providence, RI Vet About Dry Eye in Dogs and Cats

Dry eye in dogs and cats can begin with redness or stubborn discharge but progress to painful corneal ulcers, scarring, pigmentation, and impaired vision when the ocular surface remains inadequately protected. Animal Eye Care of New England provides specialty veterinary ophthalmology in the Providence, RI area, including tear testing, corneal evaluation, and treatment planning for pets with chronic ocular-surface disease. If you are searching for an eye vet near me, a veterinary ophthalmologist, a pet eye doctor, or a veterinary eye clinic for persistent discharge or suspected dry eye, contact the clinic to schedule an appointment.

This article provides general educational information about keratoconjunctivitis sicca and tear-film disorders and does not replace an individualized veterinary examination, diagnosis, or treatment plan. Use only eye medications your veterinarian has authorized and reviewed, follow recommended recheck schedules, and seek prompt veterinary attention for increased pain, cloudiness, corneal injury, or sudden vision changes.

Dry eyes can cause ongoing irritation and may lead to corneal complications when tear production remains inadequate. For pets across greater New England, including Boston, MA; Providence, RI; and Bridgeport, CT, Animal Eye Care of New England provides specialized veterinary ophthalmology. Visit our Services page for an overview of our care, or explore KCS (“Keratoconjunctivitis sicca” or dry eye), Diagnostics, Cornea, and Surgery/Procedures Offered – Face/eyelids/third eyelid for more information about diagnosis and treatment.