I've got eyes for you

Last week going up Kildaire Farm Road towards Cary, I passed a man in a green Triumph convertible with his Weimaraner sitting faithfully beside him in the passenger space with ears flapping. I tried for my blog followers to capture a picture but was unsuccessful. It was a funny moment; yet, as a veterinarian I thought about many safety issues including trash into the dog’s eyes. This brings me to today’s discussion of dry eye, Keratoconjunctivitis Sicca.

What is dry eye, Keratoconjunctivitis Sicca?

It is a disorder in the production of the water (aqueous) portion of the tears leading to a lack of lubrication of the corneal surface and surrounding tissues of the eye. The other 5% part of tears (mucous & fat) try but fail miserably to provide compensatory moisture.

What function do tears perform?

Besides lubricating comfort, tears provide anti-bacterial proteins, nutrients, and oxygen to nourish the outer surface of the eye. In addition, they wash away irritants and infections that get in eyes since the normal outer layer of the cornea does not have a direct blood supply.

What are the signs?

Initially a dog may hold the eye shut and squint a great deal. Owner will note redness and often a pet rubs at the eye a great deal. Often a thick, discolored discharge remains in the eye and surrounding eyelid in spite of persistent cleaning by the owner.  Gradually, the eye appears dull, irritated, and eventually so scarred that blindness develops. In many cases the condition is misdiagnosed as allergies or inflammation of the eye called conjunctivitis.

Are there breeds at risk?

The Bulldog, Cocker Spaniel, Lhasa Apso, West Highland White Terrier, Bloodhound, Boston Terrier, Cavalier King Charles Spaniel, English Springer Spaniel, Miniature Schnauzer, Pekingese, Pug, Samoyed, Shih Tzu, and  the Yorkshire Terrier  are the most common breeds at risk. Estimates are approximately 1% of the pet population suffers from this condition.

Besides inherited causes, what other possible risk factors lead to dry eye?

Injury to the facial nerve branch that innervates tear glands, drugs (example sulfa antibiotics such as Septra), virus infections (Distemper of dogs, Feline Herpes virus of cats), low thyroid,  immune mediated diseases (body attacking its own tissue is the most common cause), and removal of the gland are the most common factors.

How is it diagnosed?

The most common way is a strip of premeasured paper placed in the eye for 1 minute called the Schirmer tear test. Normal production of tears will “wick” on the paper at 15mm or more.  In addition, a staining of the cornea to check for concurrent ulcers and pressure check (tonopen) to check for increase pressure within the eye associated with glaucoma.

What are the preferred methods of treatment?

Topical medications such as cyclosporine (Optimmune) or tacrolimus eye drops are the most common medications applied topically in cases of immune mediated disease. In rare cases where there is a lack of response, transposition of the Parotid salivary duct to the eye is recommended to decrease the risk of scarring blindness by every time a pet eats the saliva lubricates the eyes. Additionally, topical antibiotics and lubricating artificial tears are often needed in this lifelong treatment.

Long term, what are the implications?

Although not curable, most dogs can lead relatively comfortable lives with persistent and timely application of the eye drops.

Betsy Sigmon DVM

Diplomate, American Board of Veterinary Practitioners, Canine and Feline

Hospital Director, Creature Comforts Animal Hospital

Lexi, owned by Barbara & Jim Cooper snoozing on the dock at Lake Gaston House