Dry Eye (Keratoconjunctivitis Sicca) in Dogs
The diagnosis of dry eye is made by measuring the volume of tears. The
Schirmer tear testinvolves placing a commercial filter paper strip into the
tear pool at the inner corner of the dog’s eye and leaving it for one minute to
see how much of the strip is wetted. Normally the strip should be wet to a
distance of 20mm. In dogs with dry eye, the strip wets less than 10mm (often
less than 5mm).
Treatment: For many years, the frequent application of artificial tears was
the only treatment available for dry eye. But FDA approval of ophthalmic
cyclosporin has revolutionized treatment and greatly improved results.
Cyclosporin is an immunosuppressive drug that reverses immune-mediated
destruction of the lacrimal glands.
Cyclosporin ointment is applied to the surface of the involved eye. The
frequency of application must be determined by your veterinarian. The effect is
not immediate. Artificial tears and topical antibiotics should be continued until the Schirmer tear
test indicates that the volume of tears is adequate.
Treatment is life-long. Interrupting cyclosporin for as little as 24 hours
causes symptoms to reappear in 90 percent of dogs. This can be reversed by
When damage to the lacrimal glands leaves little or no functioning tissue,
cyclosporin is not likely to be effective. Artificial tears (drops and
ointments) prescribed by your veterinarian must then be instilled into the
dog’s eyes several times a day for life. Ointments are less expensive and do
not need to be applied as frequently as drops. Saline drops should not be used
because they aggravate the problem by washing away the lipid layer of the tear
A topical mucolytic agent containing acetylcystine may be recommended to
reduce heavy mucus accumulation. Topical antibiotics are indicated whenever the
mucus discharge becomes purulent. Topical corticosteroids may be prescribed by
your veterinarian in some circumstances to decrease inflammation. In the
presence of corneal ulceration, corticosteroids are contraindicated because
they predispose a dog to rupture of the cornea.
Surgical treatment can be considered as a last resort when medical
management fails. The operation involves transplanting the duct of the parotid
gland up into the corner of the eye. The saliva takes the place of the
tears. The operation has several significant disadvantages. One is that the
volume of tears may be more than the drainage system can handle. This can
result in a watery eye and the accumulation of mineral deposits on the cornea