Diagnosis
The diagnosis is easily confirmed by using the Schirmer tear test (STT). The STT, a quick and easy test, should be performed as a routine part of the ophthalmic examination in any dog, but it must be used in every dog of a predisposed breed with conjunctivitis, even with no other clinical signs of dry eye.
Causes
Any abnormality of any one of the three layers of tears produces an unstable tear film, resulting in symptoms of keratitis sicca.
Breeds Prone To KCS
Beagle
Bulldog
Chihuahua
Japanese Chin
Kerry Blue Terrier
Pekingese
Pug
Shih Tzu
West Highland Terrier
Treatment
The goals of treatment are to restore moisture to the eye and to treat conditions such as infection or ulceration that develop because of the lack of normal tears. Tear stimulants and artificial tear replacements are used to treat KCS. Generally it will take a period of trial-and-error for your veterinarian to determine what is best for your dog. A response to tear stimulants may not occur for a few weeks or even longer, and during this time artificial tears must be used as well. Once tear production has been established, often the use of a tear stimulant once daily, or sometimes once every 2 days, will be sufficient to control KCS.
It is important to recognize that this treatment is not a cure for KCS but rather a way to manage a frustrating, painful, and potentially blinding condition. Clinical signs will slowly return If treatment is stopped. When medical therapy is unsuccessful, surgery can be done to transport one of the salivary ducts to provide moisture to the eye.
Traditional medical therapy has largely consisted of replacing the lost tears with substitutes; these include polyvinyl pyrrolidine, polyvinyl alcohol, methyl-cellulose, and hyaluronic acid. This solution does not have a primary effect on the inflammatory process, which continues progressing, nor does it contribute to some of the most important compounds of tears, such as nutrients, antimicrobial agents, or growth factors. Also, because of their quick evaporation, the substitutes have to be frequently administered.
Based on autoimmune etiology evidence, a new treatment has been recently used for KCS. Cyclosporine A (CsA), a non-cytotoxic immuno-suppressant, has been used because of its effects on tear production. It has proved to be effective on interrupting the immune-mediated reaction against lacrimal glands, cornea, and conjunctiva. The drug is a lacrimomimetic agent, even in normal eyes, and also has an anti-inflammatory effect. Different formulations for the topical use of CsA have been developed, such as eye-drops and ophthalmic ointment. Several clinical trials have demonstrated their therapeutic effects.
