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Comprehensive explanations of difficult pet health problems.


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Iris (Uveal) Cysts in Pets

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Uveal cysts (also called iris cysts) are pigmented, fluid-filled spheres that are usually brown/black or tan/yellow in color that may be attached to different parts of the interior of the eye or they may be free floating with the front (anterior) chamber of the eye. Cysts usually occur suddenly and are generally considered benign. Occasionally, they can impair eye function or vision if they are numerous or grow large enough.

Whenever your pet is showing signs of a health issue, your first step is to contact your primary care veterinarian. If it is indicated that your pet may suffer from a uveal cysts or another serious condition, a veterinary specialist is available at an ExpertVet certified hospital.



From large to small, oval to circular, and light to dark, iris cysts appear in many sizes, shapes and colors in the interior of the eye. Cysts may persist for months to years before they rupture. The rupturing of cysts is not painful. A black film can be seen on the inner surface of the cornea, usually at the bottom of the cornea.



Cysts develop spontaneously from the iris or ciliary body (located behind the iris). The specific cause of uveal cysts is not known. An underlying genetic cause is suspected. Golden Retrievers, Boston Terriers, and Labrador Retrievers are common breeds predisposed to develop uveal cysts.



An ocular examination can diagnosis uveal cysts. Cysts with a dense appearance may be mistaken for melanoma. Examination with a slit-lamp biomicroscope allows the cyst to be transilluminated so the veterinarian can determine that the cyst is hollow. Cysts can vary in size, shape, and number. Some patients need to have their eyes dilated to see the number, location and size of the cysts.



Laser coagulation can be used to remove particularly large cysts if necessary; otherwise, no treatment is needed. If glaucoma or melanoma is found, these diseases will require treatment.

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