Keratoconjunctivitis: Inflammation of the Eyes

Keratoconjunctivitis is an awfully long word that basically means any inflammation (“itis”) of both the cornea (“kerato”) or the transparent part of your eye that you see through and the “conjunctiva” -- the pink mucous membrane that covers the insides of your eyelids and attaches to the opaque, white part or sclera of the eye. You may know from your own experience that your eyes are vulnerable to trauma and irritation from things like wind, dryness, infections and foreign bodies. It’s not surprising, then, that your dog’s eyes are also sensitive to developing keratoconjunctivitis.

What are the symptoms of keratoconjunctivitis?
Again, you can probably guess this based on your own experience. The inflammation causes:

  • Redness
  • Swelling of the eyelids and conjunctiva
  • Itchiness (your dog may rub his face and eyes)
  • Pain
  • Squinting (either from pain or from sensitivity to light)
  • Discharge from eyes (clear, excessive tearing to thicker, mucous) that might even ‘glue’ eyelids closed especially after sleeping
  • Cloudy appearance of the corneal surface
  • Decreased visual acuity

Not all symptoms will occur in all cases and the condition may only exist in one eye or both eyes depending on the cause.

What causes keratoconjunctivitis in dogs?
Remember, since this is an “itis,” it can be caused by anything that causes irritation or inflammation to the eye. Some causes include:

  • Environmental irritants (dryness, dust, smoke, etc.)
  • Allergies
  • Infections like distemper
  • Immune-mediated disorders
  • Keratoconjunctivitis sicca or dry eye

The last one, Keratoconjunctivitis sicca (known as KCS) or ‘dry eye’ is a very common disorder in dogs. Just as keratoconjunctivitis in general can have many causes, so can the more specific KCS. KCS can also be due to a hereditary predisposition (like in Cocker Spaniels, Boston Terriers and other breeds) and often times due to an immune mediated disorder where your dogs own immune system is the culprit1.

As the name, dry eye, implies, the issue in KCS is a lack of adequate moisture/tears in the eye. Normal tears in normal amounts are essential for healthy eyes. Imagine if you had blood vessels running across the surface of your eye. It would be difficult to see properly. That’s why they aren’t there. But nutrients and antibodies and everything else that blood would deliver to your eyes has to get there somehow. That’s what tears do. Without them bad things happen -- more inflammation or infection occurs, the cornea dries out, it becomes cloudy, opaque, ulcerated and or pigmented and vision is impaired. If left untreated these changes are at the very least extremely painful, and in the worst cases they can be irreversible so that your dog may even lose his sight.

How is keratoconjunctivitis diagnosed and treated?
Your veterinarian will, of course, need to do a thorough examination of your dog’s eyes (checking for any abnormalities, ulcers, tear production and vision deficits). In addition, a complete physical examination and other tests may be needed to rule out any suspected underlying problems that might be contributing to the inflammation in your dog’s eye(s) so those can be addressed while specific treatment for the ocular symptoms are instituted.

In general, you can expect that the application of some form of eye drops or ointments will be required to bring your dog relief. The type of product may vary depending on the presence or absence of infection, ulcers, cloudiness, etc. In cases of KCS, replacement artificial tears need to be instilled in the eye multiple times a day -- at least temporarily and in many cases forever going forward. In other cases, a topical preparation including immunosuppressant drugs like Cyclosporine or Tacrolimus applied twice daily can be very effective in stimulating natural tear production again (though even that will need to be continued for the life of your dog)1.

Your ultimate goal is not only to keep your dog comfortable in the short term but also to preserve vision for the long haul. Keratoconjunctivitis and KCS should be treatable, controllable problems even if they aren’t entirely curable, but it is very important that you follow your veterinarian’s recommendations and instructions in order to obtain the very best outcome possible.

If you have any questions or concerns, you should always visit or call your veterinarian -- they are your best resource to ensure the health and well-being of your pets.

1. "Keratoconjunctivitis Sicca." NC State University - College of Veterinary Medicine. Web.


Prognosis depends on the underlying etiology of KCS and the patient’s response to treatment ( Table 2 ). If KCS does not respond to medical therapy, the prognosis is worse for vision retention. In addition, most patients will require lifelong therapy with topical immunosuppressive medications.

Recently, chronic keratitis treated long-term with tacrolimus or CsA has been tenuously associated with increased risk for corneal squamous cell carcinoma. 30 However, because the study was retrospective, clinical data are lacking, and KCS alone may have resulted in a predisposition to this condition. While this study is interesting, KCS should be treated as described in this article.

Dogs with a diagnosis of KCS should be evaluated every 6 to 12 months to assess effect of treatment and progression of disease.

CsA = cyclosporine A KCS = keratoconjunctivitis sicca PTF = precorneal tear film STT = Schirmer tear test STT1 = Schirmer tear test 1 TBUT = tear film breakup time


  1. King-Smith PE, Fink BA, Fogt N, et al. The thickness of the human precorneal tear film: Evidence from reflection spectra. Invest Ophthalmol Vis Sci 2000 41(11):3348-3359.
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Lori J. Best, DVM, is a first-year ophthalmology resident at University of Tennessee College of Veterinary Medicine. She received her DVM from Colorado State University and completed her small animal rotating internship at University of Tennessee.

Diane V.H. Hendrix, DVM, Diplomate ACVO, is a professor of ophthalmology at University of Tennessee College of Veterinary Medicine. She received the Zoetis Distinguished Veterinary Teaching Award in 2013. Dr. Hendrix received her DVM from University of Tennessee and completed her residency in comparative ophthalmology at University of Florida.

Dan A. Ward, DVM, PhD, Diplomate ACVO, is a professor of ophthalmology at University of Tennessee College of Veterinary Medicine. He received the Pfizer Distinguished Professor Award in 2012. Dr. Ward received his DVM from University of Tennessee and completed his ophthalmology residency, PhD in pharmacology, and postdoctoral work in clinical pharmacology at University of Georgia.

Conjunctivitis and Keratitis

Conjunctivitis is the inflammation of the pink membranes surrounding the eye. Keratitis is inflammation of the cornea. These two conditions can be caused by viral, bacterial, or allergy-driven infection.

Dry Eye (Keratoconjunctivitis sicca)

DJ Haeussler, Jr., BS, MS, DVM, DACVOChristina Korb, DVM

What is KCS?

Keratoconjunctivitis sicca (KCS), or dry eye, is an ocular condition commonly diagnosed in dogs. It is less common in other species. Keratoconjunctivitis sicca results most often from an inadequate quantity of tears or a deficient quality of tears. Tears are produced by the lacrimal, or tear gland, and the gland of the third eyelid. Tears are needed to provide lubrication and nutrition to the cornea, as well as remove debris and/or infectious agents from the eye.

What causes KCS?

The most common cause of KCS in the dog is immune mediated inflammation of the tear glands. Other causes of KCS include but are not limited to:

  • Congenital disease, such as small or absent lacrimal glands
  • Infectious disease, such as canine distemper virus
  • Neurologic deficiency, such as loss of nerve innervation to the eye
  • Endocrine disease, including hypothyroidism, Cushing’s disease, and diabetes mellitus
  • Prolapsed gland of the third eyelid (“cherry eye”) and/or removal of the gland of the third eyelid
  • Radiation therapy near the eye
  • Drug toxicity, including use of sulfa derivative medications

Certain breeds are more likely to develop KCS, suggesting there is a genetic basis. Commonly affected breeds include the Cavalier King Charles Spaniel, English Bulldog, Lhasa Apso, Pug, Shih Tzu, and West Highland White Terrier. However, regardless of breed, any dog can be affected with KCS.

How is KCS diagnosed?

The most common clinical signs of KCS include painful, red eyes, with thick mucoid discharge. Dry eye most commonly occurs in both eyes, and some animals may develop secondary corneal ulceration or bacterial conjunctivitis. Corneal ulceration with secondary infection can lead to loss of an eye. Chronic, uncontrolled dry eye may also lead to corneal pigmentation, vascularization, and scarring, which may lead to visual impairment.

Several important diagnostic tests are involved in diagnosis of KCS. The most important test involves looking at the corneal surface cells and tear film with an instrument called a biomicroscope. Paper test strips called Schirmer Tear Test strips may also be utilized to quantify tear production from both eyes. If your pet has a normal tear quantity but has clinical signs of KCS, your veterinary ophthalmologist may also perform a tear film break-up time test to support a diagnosis of a qualitative tear film deficiency.

How is KCS treated?

Treatment of KCS includes daily lifelong administration of topical tear stimulant medication. These medications reduce inflammation, as well as stimulate natural tear production. They are typically administered two to three times daily and are safe to give long term. Specific dosing instructions will be made by your veterinary ophthalmologist. Concurrent use of tear replacement lubricating drops may help improve comfort for many pets.

The majority of dogs respond favorably to drops, but in severe cases of KCS that are poorly responsive to medical management, a surgical procedure called a parotid duct transposition may be recommended. The procedure involves redirecting the parotid salivary duct from the mouth to the eye in order to provide salivary secretions to the cornea. Parotid duct transposition often results in a more comfortable patient with less chance of corneal ulceration.

What is the prognosis for KCS?

Early diagnosis with lifelong treatment, as well as routine follow-up examinations is of paramount importance for patients with KCS. In the majority of dogs, prognosis can be excellent for long-term comfort and maintenance of vision.

Figure 1: KCS sample


Entropion is an inward rolling of the eyelid. The problem is most common in the Shar Pei, Chow Chow, Bulldog, Retrievers, Rottweiler, and Setters. Although the exact genetic pattern is usually not known, the problem is most likely caused by many genes that are responsible for the overall head and face conformation. Therefore, we recommend that you do not breed your pet since the problem can be passed to the puppies.

When the eyelids roll in, the hair on the outside of the lid rubs on the surface of the eye and cause corneal irritation. In some patients, entropion leads to corneal ulceration. Common symptoms associated with entropion include squinting, tearing, and rubbing.

The treatment for entropion is surgery to remove excess skin and muscle along the eyelid margin. This is cosmetic surgery and after reconstructing the eyelid, the lids should look normal.

Watch the video: Ophthalmology 116 a Herpes Simplex Keratitis Virus Cornea Dendritic ulcer HSV Eye infection

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