Canine Dry Eye: Recognizing Keratoconjunctivitis Sicca (KCS) in Dogs

Key Points:

1. Keratoconjunctivitis Sicca (KCS) is a common eye problem in domestic dogs.
2. Short-nosed dogs (brachycephalic breeds, e.g., pugs, Boston terriers, Shih Tzus) are at higher risk than long-nosed (dolichocephalic breeds).
3. KCS can result from immune destruction of the tear glands, genetics, neurologic damage, removal of the third eyelid (nictitans), and chronic topical steroid use, among other reasons.
4. Promptly recognizing signs of eye discomfort in your dog is critical. When noted, seeking veterinary care straightaway can minimize the chance of secondary infections and corneal ulcer development and improve quality of life.
5. Therapy for KCS is life-long, so never run out of medications.

Keratoconjunctivitis Sicca, what is it?

KCS refers to the clinical condition commonly known as dry eye. The name translates to corneal inflammation and drying out of the surrounding tissues. It develops secondary to inappropriate fluid production from the eye’s aqueous tear film, generally made by the lacrimal (tear) gland and the gland of the third eyelid (nictitans). Our tears help clean the eyes of debris, lubricate the eyes, and help to prevent infection. Further, they provide nutrition to the outermost surface of the eye, the cornea.

There are three types of dog dry eye 

1. Quantitative KCS is a decrease in the watery part of the tear film, as measured by the Schirmer tear test (STT). The most commonly seen form in dogs.
2. Qualitative KCS occurs when the tear film breakup time is slower than normal. This results when there is a reduction in the mucin or fat portions of the tear film.
3. Neurogenic KCS uncommonly develops in dogs. It occurs when a facial nerve injury affects the eye-related areas of the head.

Symptoms of KCS

KCS may look like other eye problems; regardless, the signs make it clear that something isn’t normal with the eyes. Most veterinarians can tell from a mile away a dog with KCS because they show signs, including

• Painful eyes — Squinting, blinking excessively, holding the eye(s) closed, pawing at the eyes/rubbing the head on furniture),
• Redness,
• Eye discharge — Generally starts off as clear, thin, not overtly concerning, and progresses to a thick, yukky, often yellow to yellowish-green mucoid discharge,
• Vision loss — Vision may be decreased or absent in chronic cases,
• Hyperpigmentation— Scarring from long-term damage causes the pigment to build up on the cornea,
• Blood vessels may trace along the cornea (neovascularization)
• Many dogs may also have evidence of corneal ulcers.

Usually, typical KCS affects both eyes, though, in the initial stages, they may not show signs simultaneously. This can occur at any age but usually develops in middle to older-aged dogs.

Causes of KCS

Causes can be varied from one dog and breed to another and includes anything that negatively affects the ability of the eyes to produce sufficient tears. Examples include

• The most common cause is due to immune-mediated destruction of or damage to the tear-producing glands,
• Congenital diseases, e.g., lack of tear-producing glands or small glands
• Certain medications, when either applied topically (steroids) or taken orally (antibiotics in the sulfa class of drugs)
• Infectious diseases such as distemper virus,
• Hypothyroidism (low thyroid production)
• Diabetes
• Cushing’s disease
• Third eyelid removal for a ‘cherry eye’— A cosmetic issue generally, when the third eyelid pops out and is visible on the eye’s surface. This should be treated with a tacking procedure, not removal. However, some vets still remove the nictitans resulting in an increased risk of KCS,
• Trauma or other damage to the facial nerve resulting in neurogenic KCS
• A short-term decrease in tear production occurs after general anesthesia (lasting 2-4 hours post)

KCS at-risk breeds

Those adorable smooshed face breeds so many love and several other breeds are at a higher risk of developing KCS. These include English bulldogs, American cocker spaniels, Lhasa Apsos, Shih Tzus, West Highland White terriers, Cavalier King Charles spaniels, and pugs. However, any breed can become affected.

Diagnosis of KCS

The primary diagnosis starts with a STT. For veterinarians, Diagnosing KCS is easy. One of those gratifying moments that takes only a few minutes to diagnose. We take a test strip and hold it in the lower lid of your dog’s eye for 60 seconds. (It likely seems like the longest minute ever, but most dogs tolerate it surprisingly well). We watch as a blue color and wetness develop and wick up the strip. There are numbers on the strip, and we wait for the full 60 seconds and then read the strip. A normal STT is anything > 15 mm/min.

Diagnostics must also include ruling out other underlying diseases, as dry eye can lead to infection and secondary ulcers or abrasions on the eye. Further, we want to rule out glaucoma (increased pressure in the eyes). So, in addition to the Schirmer Tear Test, we want to also

1. Fluorescein stain is applied to the eyes to check for defects in the cornea (eye ulcers),
2. Tonometry – This test assesses for the presence of glaucoma by checking the pressures within the eyes,
3. For qualitative tear film disorders, we assess the tear film quality. This is done by determining how quickly the tear film breaks apart. Moreover, a rose bengal or lissamine green stain is diagnostic for qualitative KCS.

Qualitative tear film disorders

Some dogs have normal Schirmer tear tests yet show all the indications of dry eye. These dogs have enough tears, but their quality is poor. Thus, their eyes are not adequately protected. Qualitative tear problems are less common, yet appropriate tear production does not rule out a problem. Therefore, have your vet evaluate the tear film. If abnormal, your dog may react to KCS immunomodulatory drugs and lubricants.

Treatment of KCS

Treatment goals include

• Stimulating tear production,
• Replacing the tear film to protect the eyes,
• Providing lubrication,
• Keeping the eyes and skin around the eyes clear from discharge, and
• Treat any underlying infection, ulceration, and inflammation.

Treating standard KCS

Treatment for qualitative and quantitative KCS consists of the same therapies. Many dogs at the time of diagnosis have underlying irritation, inflammation, and or infection or ulceration in the eyes. As a result, many dogs are placed on topical antibiotics and pain management therapy (oral/topical). Additionally, an e-collar (those silly lampshade cones) is worn to prevent rubbing or pawing at the eyes if an infection is present. At the same time, a specific medication is started to help stimulate the immune system to produce more tears.

Another key component of treatment involves lubricating the eyes, which helps us to replace or improve the tear film. Finally, keeping the eyes clean and clear of discharge and healthy skin above and below the eyes is critical. Using appropriate moist cloths or wipes safe for the eyes can help lessen complications and improve your pet’s comfort.

Products such as artificial tears or Optixcare® products can be used multiple times a day to lubricate the eyes. These products take the place of tears, keeping the eyes moist and allowing the pet to blink away any debris, minimizing the risk of irritation, ulceration, and pain.

The most commonly used topical immune stimulatory therapies in dogs with KCS include cyclosporine and tacrolimus. These drugs prevent T-cells from activating (cells in the immune response). This reduces the inflammatory process in tear gland tissues and helps diminish or resolve symptoms associated with KCS in most dogs. But drug concentration matters! Only one FDA-approved dog-specific product exists to treat decreased tear production in dogs, cyclosporine 0.2% ophthalmic ointment (Optimmune®). However, unless this is started when tear production just drops a point or two below normal, the concentration is too low to achieve the desired improvements needed to protect the eyes and improve quality of life.

Instead, specially compounded formulations of one of the following may be prescribed.

• Cyclosporine 1% to 2% compounded in an oil or aqueous-based solution
• Tacrolimus 0.02% to 0.03% compounded in an oil or aqueous-based solution

Regardless of the cause, once the secondary ailments resolve, therapy is maintained with the immunomodulator medications for life! Ensure you budget wisely and never run out of drugs; refill on time.

Neurogenic KCS and treatment

Neurogenic KCS represents a subtype of dry eye. Anything that causes damage to the tear-producing glands, e.g., infection of or trauma to the facial nerve, can lead to neurogenic KCS. In addition to the typical clinical signs of KCS, the nostril on the same side of the body where the nerve was affected generally becomes crusty and dry.

In addition to using either cyclosporine or tacrolimus, pilocarpine, a human oral medication, is preferred over the topical version. This medication works by stimulating the lacrimal glands to produce more tears. However, it can taste bitter, so it should be placed on absorbent food and ensured that it is entirely eaten by the pet. Side effects can develop with a minimal dose, including drooling, decreased appetite, diarrhea, or vomiting. A topical formulation may be tried if the oral is not tolerated. Still, it can irritate the eyes and is less effective than the oral form.

My dog bites when I get near the eyes; now what?

Many dogs with KCS have had painful eyes, eye infections, ulcers, or other concerns with their eyes and often for long periods without relief. You may constantly be wiping their eyes with a wipe or towel. They, understandably, resent you coming at the head and eyes all the time, and many may be a bit snippy, even biting loved ones. Sadly, you cannot reason with them or explain that they will feel better if they let you treat their eyes. But one thing you can consider is cooperative care training.

Cooperative care training is a form of positive reinforcement training that helps the pet parent, and pet mutually agree on helpful training cues, when is a good time and when isn’t to handle them, and how best to handle them. Be patient. This type of training takes time, days, weeks, or even months, depending on the pet. But the way it works is simple. It allows your dog to consent and say, “yes, it is ok to touch me” or “no, I am not ok with this right now; maybe later.”

Cooperative care training minimizes restraint and hands-on needs and allows a mutually respectful interaction. It should be considered for any breed at risk for KCS or other eye problems, dogs with ear infections, or who need to be handled or bathed easily. Check out this book by Dr. Deborah A. Jones, Cooperative Care: Seven Steps to Stress-Free Husbandry. As a veterinarian, the author strongly recommends it; as a pet parent, it has been a blessing for Dr. Tramuta-Drobnis and her dog, Jazzy.

KCS prognosis

The saying goes that the ‘eyes are the window to the soul,’ so preserve your pet’s eyes. If you notice discharge, squinting, cloudiness, pawing at the eye, or other signs, have your dog evaluated sooner than later. Delaying treatment when minor eye problems appear may result in persistent alterations to the eyes, which ultimately cause vision loss and reduce your pet’s quality of life. Don’t wait too long if you see signs of KCS; see your veterinarian.

Luckily, when recognized early, KCS can be easily treated, though therapy is life-long! Dogs can retain vision when treatment is started early in the disease process and when owners consistently apply the medications daily. They can remain free of corneal ulcers and discomfort as well. Starting therapy when tear production is just below normal can minimize risks over time and keep your furry friend comfortable and happy.