Keratoconjunctivitis Sicca

TL;DR. Keratoconjunctivitis sicca (KCS), commonly known as dry eye, is a painful condition where a pet cannot produce enough tears, leading to chronic eye irritation, thick discharge, and potential vision loss that requires lif

Thick, sticky mucoid discharge and a dull corneal surface are classic signs of keratoconjunctivitis sicca (KCS) in dogs.

Là gì?

Keratoconjunctivitis sicca (KCS), widely referred to as "dry eye," is a common and potentially serious ophthalmic disorder in dogs, and less frequently, in cats. The term literally translates to inflammation of the cornea (kerato) and the conjunctiva (conjunctivitis) due to dryness (sicca). To understand KCS, it helps to understand the tear film. The tear film is not just water; it is a complex, three-layered barrier that coats the eye. It consists of an outer oily (lipid) layer that prevents ev

"A deficiency in any of these components may result in decreased tear production or increased tear clearance (evaporation) and may be diagnosed with a Schirmer tear test. Clinical signs of a tear film abnormality depend on the severity, chronicity, and underlying cause of the tear deficiency."

Nguyên nhân và yếu tố nguy cơ

The vast majority of KCS cases in dogs are immune-mediated. In these patients, the animal's own immune system mistakenly targets and destroys the lacrimal (tear-producing) glands. A prominent veterinary pharmacology reference explains: While immune-mediated destruction is the primary culprit, other causes and risk factors exist: * Neurogenic KCS: This form occurs when the nerve supply to the tear glands is disrupted. The parasympathetic nerve fibers that stimulate tear production travel al

Dấu hiệu

• Neurogenic KCS: This form occurs when the nerve supply to the tear glands is disrupted. The parasympathetic nerve fibers that stimulate tear production travel alongside the facial and trigeminal nerves. If these nerves are damaged by trauma, middle ear infections, or inflammatory disease, the tear gland stops functioning. Interestingly, because these same nerves supply the lateral nasal gland, pets with neurogenic KCS often present with a dry, crusty nose on the same side as the dry eye.
• Anesthesia-Induced Dryness: General anesthesia temporarily halts tear production. If a pet's eyes are not protected during surgery, they can suffer severe corneal drying. A veterinary critical care manual emphasizes:
• Drug Toxicities: Certain systemic medications, most notably sulfonamide-containing antibiotics (sulfa drugs), can cause temporary or permanent toxicity to the tear glands.
• Congenital Defects: Some dogs are born without fully developed tear glands (lacrimal gland aplasia).
• Infectious Diseases: In cats, KCS is relatively rare but is most commonly associated with chronic feline herpesvirus (FHV-1) infections, which cause severe inflammation and scarring of the conjunctiva and the tear ducts.
• Thick mucoid discharge (Cardinal): This is the most consistent and obvious finding. Because the watery portion of the tear film is missing, the mucus and oil layers remain, creating a thick, sticky, yellowish-green discharge that clings to the eyelids and the surface of the eye.

Khi nào gặp bác sĩ thú y

If your pet has been diagnosed with KCS, or if you suspect they are developing it, you should monitor their eyes daily. You must call your veterinarian immediately if you notice any of the following red flags: * Sudden squinting, blinking, or holding the eye shut (signs of severe pain or a corneal ulcer) * **A change in the clarity of the eye, such as a white, grey, or blue spot on the

Chẩn đoán

Diagnosing KCS is straightforward and relies on a quick, non-invasive test called the Schirmer Tear Test (STT). This is the gold standard diagnostic tool for dry eye. During a Schirmer tear test, your vet will place a small, specialized, calibrated paper strip inside the lower eyelid of your pet's eye. The strip is left in place for exactly 60 seconds. As tears are produced, they travel up th

Điều trị

Treating KCS requires a multi-pronged approach aimed at stimulating natural tear production, replacing missing tears, and reducing inflammation. Because the vast majority of cases are immune-mediated, immunosuppressive eye drops are the cornerstone of therapy. ### First-Line Therapy: Cyclosporine Cyclosporine is an immunosuppressant ophthalmic agent that targets

Phòng ngừa và sinh hoạt

Because the primary cause of KCS is an inherited, immune-mediated condition, there are no proven lifestyle changes or preventive measures to stop the disease from developing. However, you can prevent the severe, vision-threatening complications of KCS through: * Routine screening: Asking your vet to perform a Schirmer tear test during annual

Nguồn

Veterinary internal medicine references for this condition.

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