Sicca, also known as "Dry Eye" and scientifically known as Keratoconjunctivitis Sicca, is a disorder in dogs that decreases the animal's ability to produce tears. When a dog has the disorder, its eye ducts produce an excess amount of mucus in place of tears, which causes the texture of the cornea on the eye to appear thick and dry.
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Symptoms
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When a dog is infected with sicca, symptoms of dryness, cloudiness and dullness replace the usually shiny and bright appearance of the cornea on the outer surface of the eye. The disorder also may cause repeat bouts of conjunctivitis (red eye), and can eventually cause ulcers and symptoms of the condition keratitis, a disease that causes the cornea to become inflamed. If untreated, sicca can eventually lead to blindness in the infected animal.
Possible Causes
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According to MedicineNet.com, there are a few conditions that may cause the disorder sicca. One is an injury to the dog that damages the nerves in the lacrimal glands, and usually only affects one eye. A direct injury to the tear glands may also cause sicca to form. Also, some dogs have a congenital condition that causes missing tear glands, which can cause the disorder.
Assessment
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In order to diagnose whether a dog has sicca, a veterinarian measures the volume of the animal's tears. This procedure is called the Schirmer Test, which the veterinarian performs by placing a paper filter strip in the tear pool at the inner corner of the eye, leaving it in for one minute. The normal measurement of water volume is 20mm, and the veterinarian confirms the dog has the condition sicca if this measurement is below 10mm.
Treatments: Cyclosporin
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There are various forms of treatment for sicca. A veterinarian can apply Cyclosporin--an immunosuppressive drug that reverts immune-induced destruction of the lacrimal glands--to the surface of the affected eye. When this treatment is used, the veterinarian must apply the drug for the remaining life of the dog in order to avoid reappearing sicca symptoms, which have a 90% chance of returning if they are left untreated for a period of over 24 hours.
Treatments: Artificial Tear Instillment
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In cases where the lacrimal glands are damaged to an extent where the tissue is hardly working or no longer functioning, the treatment of Cyclosporin is not effective. In this situation, a veterinarian must prescribe artificial tears, which the dog's owner places in the dog's eyes in the form of drops. An owner must apply these artificial tears several times a day for the rest of the dog's life.
Treatments: Other Topical Remedies
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In order to remove the heavy accumulation of mucus in the dog's eyes caused by sicca, a veterinarian can apply a topical mucolytic agent, which contains acetylcystine. When the mucus discharge around the dog's eye forms decay, the veterinarian may prescribe topical antibiotics in order to stunt its growth. In cases where sicca causes the eye to become inflamed, the veterinarian may also prescribe topical corticosteroids to inhibit the swelling.
Treatments: Surgery
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If all the previous treatments fail, a pet's owner may choose surgery to remedy the sicca. The veterinary surgeon transplants the duct of the dog's parotid salivary gland into the corner of the dog's eye. The saliva then replaces the function of the tear gland. This is normally used as a last option, however, because there is a risk that an excess amount of tears will form in the eye as a result of the procedure.
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