Tumor of the Eye in Dogs

Uveal melanoma is a cancer (melanoma) of the eye involving the iris, ciliary body, or choroid which are  collectively referred to as the uvea. Tumors arise from the pigment cells (melanocytes) that reside within the uvea giving color to the eye. These melanocytes are distinct from the retinal pigment epithelium cells underlying the retina that do not form melanomas.

A uveal melanoma is usually located on the iris (the colored part of the eye) or on an internal portion of the dog’s eye that is hard to observe.Initially, most uveal melanomas are benign and unilateral, affecting the anterior of uvea the most. In only a very small percentage of affected dogs (about 4%) will the tumor spread to other parts of the body. In addition, as long as the tumor is not blocking your dog’s pupil, in most cases your dog’s vision will not be impacted by the tumor.

Uveal melanomas represent the most common primary intraocular tumor. The iris is most often affected, with the ciliary body and/or choroid affected secondarily by extension. These tumors appear as a densely pigmented, localized mass within the iris.

Symptoms are anterior and chorodial malanoma are 

Anterior Uveal Melanoma

Pigmented scleral (white part of the eye) or corneal (the transparent front part of the eye) mass

Pigmented mass visible

Irregular pupil

Inflammation of the eye (the uvea)

Glaucoma (Increased pressure in the eyes)

Hyphema  (Blood in the eye)

No vision loss unless mass obstructs the pupil or glaucoma has developed

Choroidal Melanomas

Often missed because of tumor location

Mass farther back in the eye

Very slow-growing; rarely requires removing the eye

Rare tumor

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