Chronic dry eye, medically referred to as keratoconjunctivitis sicca or KCS, is when a pet is not producing a sufficient amount of tears. This can cause mild to extreme discomfort for the affected pet. Over time, this condition can cause mild to severe or even permanent vision loss.
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Symptoms
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The most common symptom of chronic dry eye is a thick discharge which may be yellow in color. The discharge occurs because there are little or no tears to flush out bacteria, pollen, dust and more.
Additional symptoms include chronic redness of the eye, a development of a filmy layer over the affected eye and decreased or a total loss of vision.
Diagnosis
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If you suspect your pet has chronic dry eye, you should see a veterinarian as soon as possible. Your veterinarian will be able to perform a test that will properly diagnose chronic dry eye and provide your pet with relief.
To diagnose chronic dry eye, your vet will use a test that measures tear production. This test, referred to as the Schirmer tear test, uses a small strip of absorbent material that is placed directly onto the affected eye. For approximately one minute, the strip of material will absorb any tear production. Then, the strip is measured and compared to the expected amount of tear production. This will allow your veterinarian to determine if chronic dry eye is the cause.
Causes
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There are several reasons for KCS to occur. The most common reason is due to an immune mediated destruction of the gland which produces natural tears (See Reference 1, 2). Currently, the reason for the occurrence of this destruction is unknown but certain breeds such as the West Highland white terrier, the American cocker spaniel and the miniature schnauzer are prone to this condition (See Reference 2).
In other cases, KCS can occur due to certain medications that your pet may be taking, hypothyroidism, trauma to the eyes, skin diseases, chronic infections of the eye, neurological disorders and even canine distemper.
Medications
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Most cases of chronic dry eye are also accompanied by an infection. This is because the tears do not flush out the bacteria and an infection occurs. Your veterinarian will treat your pet's infection in addition to prescribing a treatment for your pet's chronic dry eye. In most cases, an ointment or drops are recommended. However, some cases may require an artificial tear solution.
Surgical Solutions
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In rare cases of severe chronic dry eye, there is a surgical option. In the procedure, a saliva duct is removed from the cheek and then placed within the upper eyelid. This allows for saliva to drain into the eye, thus creating artificial tears. This particular surgery is referred to as parotid duct transposition (See Reference 3).
If the pet has this surgery, for the rest of the pet's life it is possible for mineral buildups to occur. Occasional cleaning or eyedrops will be prescribed by your veterinarian to remove these. Your pet may also have excess tear production in the affected eye during feeding, so you will need to wipe this up regularly. However, this treatment can provide great relief to dogs with severe chronic dry eye.
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