Canine Iris Melanosis

Check your dog's eyes for pigment changes during regular grooming times.
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Iris melanosis is a pigment change in the eye, similar to a freckle. Melanosis itself causes no health issues. However, this change in eye color requires frequent and regular monitoring as it can be an initial sign of melanoma development. In addition, these color changes can cause an increase in eye pressure, resulting in glaucoma. If you notice pigment changes or spots in your dog’s eyes, consult a veterinarian to have him evaluated.


The extent of pigmentation changes in the iris varies from dog to dog. While one dog may have a small dot, similar to a freckle, color changes spread over large areas in others. Typically the changes will be in one eye only. Color changes may increase or spread to other areas of the iris over time. Consider taking regular pictures of your dog’s eyes in order to track color changes.


Because these pigment changes do not cause medical issues, no treatment is necessary. Your veterinarian will want to monitor and check your dog’s eyes frequently for any changes. Iris melanosis can be a precursor of iris melanoma, or tumors on the eye. If the pigment change occurs in an area where it blocks intraocular fluid, it can cause secondary glaucoma. If these conditions go untreated, vision disturbances or complete blindness can occur.


If the pigmentation causes increased eye pressure, glaucoma is a concern. Symptoms of glaucoma include eye redness or cloudiness, dilated pupils and constant blinking. Symptoms outside the eye include headaches, loss of appetite and changes in basic behavior. Your dog may be less active or refuse to play or exercise. Glaucoma treatment may involve medication to reduce pressure, surgery to reduce eye fluid or eye removal. Unfortunately, 40 percent of dogs diagnosed with glaucoma suffer blindness and eye degeneration within the first year.


Iris melanomas in dogs typically confine themselves to the eye and do not metastasize to other areas of the body. If iris melanosis develops into a melanoma, the pigment change develops into a raised mass. Conservative treatment involves regular monitoring of the melanoma and looking for growth or secondary conditions, such as glaucoma. Laser removal is an option for small masses. Fast-growing melanomas require complete removal of the affected eye.